diff --git a/lib/sinon/assert.js b/lib/sinon/assert.js
index 5b7e02a7b..f7e0e35c1 100644
--- a/lib/sinon/assert.js
+++ b/lib/sinon/assert.js
@@ -107,7 +107,9 @@ assert = {
         throw error;
     },
 
-    pass: function pass() {},
+    pass: function pass() {
+        return;
+    },
 
     callOrder: function assertCallOrder() {
         verifyIsStub.apply(null, arguments);
diff --git a/lib/sinon/spy.js b/lib/sinon/spy.js
index 2392f51db..de65b1b7d 100644
--- a/lib/sinon/spy.js
+++ b/lib/sinon/spy.js
@@ -38,7 +38,9 @@ function spy(object, property, types) {
     }
 
     if (!object && !property) {
-        return spy.create(function () {});
+        return spy.create(function () {
+            return;
+        });
     }
 
     if (!types) {
@@ -150,7 +152,9 @@ var spyApi = {
         var name;
 
         if (typeof func !== "function") {
-            func = function () { };
+            func = function () {
+                return;
+            };
         } else {
             name = functionName(func);
         }
diff --git a/test/assert-test.js b/test/assert-test.js
index 5a3dae6d1..38dc0ff1b 100644
--- a/test/assert-test.js
+++ b/test/assert-test.js
@@ -38,8 +38,8 @@ describe("assert", function () {
     });
 
     it("supports proxy property", function () {
-        var api = { method: function () {} };
-        api.method.proxy = function () {};
+        var api = { method: function () { return; } };
+        api.method.proxy = function () { return; };
         sinonSpy(api, "method");
         api.method();
 
@@ -114,7 +114,7 @@ describe("assert", function () {
 
             it("fails when method is not stub", function () {
                 assert.exception(function () {
-                    sinonAssert.called(function () {});
+                    sinonAssert.called(function () { return; });
                 });
 
                 assert(sinonAssert.fail.called);
@@ -176,7 +176,7 @@ describe("assert", function () {
 
             it("fails when method is not stub", function () {
                 assert.exception(function () {
-                    sinonAssert.notCalled(function () {});
+                    sinonAssert.notCalled(function () { return; });
                 });
 
                 assert(sinonAssert.fail.called);
@@ -234,7 +234,7 @@ describe("assert", function () {
 
             it("fails when method is not stub", function () {
                 assert.exception(function () {
-                    sinonAssert.calledOnce(function () {});
+                    sinonAssert.calledOnce(function () { return; });
                 });
 
                 assert(sinonAssert.fail.called);
@@ -502,7 +502,7 @@ describe("assert", function () {
                 sinonStub(this.stub, "calledOn");
 
                 assert.exception(function () {
-                    sinonAssert.calledOn(function () {}, object);
+                    sinonAssert.calledOn(function () { return; }, object);
                 });
 
                 assert.isFalse(this.stub.calledOn.calledWith(object));
@@ -583,7 +583,7 @@ describe("assert", function () {
                 sinonStub(this.stub, "calledWithNew");
 
                 assert.exception(function () {
-                    sinonAssert.calledWithNew(function () {});
+                    sinonAssert.calledWithNew(function () { return; });
                 });
 
                 assert.isFalse(this.stub.calledWithNew.called);
@@ -659,7 +659,7 @@ describe("assert", function () {
                 sinonStub(this.stub, "alwaysCalledWithNew");
 
                 assert.exception(function () {
-                    sinonAssert.alwaysCalledWithNew(function () {});
+                    sinonAssert.alwaysCalledWithNew(function () { return; });
                 });
 
                 assert.isFalse(this.stub.alwaysCalledWithNew.called);
@@ -952,7 +952,7 @@ describe("assert", function () {
 
             it("fails if method is not fake", function () {
                 assert.exception(function () {
-                    sinonAssert.alwaysCalledOn(function () {}, {});
+                    sinonAssert.alwaysCalledOn(function () { return; }, {});
                 });
             });
 
@@ -1005,7 +1005,7 @@ describe("assert", function () {
 
         it("fails if method is not fake", function () {
             assert.exception(function () {
-                sinonAssert.alwaysCalledWith(function () {});
+                sinonAssert.alwaysCalledWith(function () { return; });
             });
         });
 
@@ -1163,7 +1163,7 @@ describe("assert", function () {
     describe("message", function () {
         beforeEach(function () {
             this.obj = {
-                doSomething: function () {}
+                doSomething: function () { return; }
             };
 
             sinonSpy(this.obj, "doSomething");
@@ -1217,7 +1217,7 @@ describe("assert", function () {
         });
 
         it("assert.callOrder exception message", function () {
-            var obj = { doop: function () {}, foo: function () {} };
+            var obj = { doop: function () { return; }, foo: function () { return; } };
             sinonSpy(obj, "doop");
             sinonSpy(obj, "foo");
 
@@ -1233,7 +1233,7 @@ describe("assert", function () {
         });
 
         it("assert.callOrder with missing first call exception message", function () {
-            var obj = { doop: function () {}, foo: function () {} };
+            var obj = { doop: function () { return; }, foo: function () { return; } };
             sinonSpy(obj, "doop");
             sinonSpy(obj, "foo");
 
@@ -1247,7 +1247,7 @@ describe("assert", function () {
         });
 
         it("assert.callOrder with missing last call exception message", function () {
-            var obj = { doop: function () {}, foo: function () {} };
+            var obj = { doop: function () { return; }, foo: function () { return; } };
             sinonSpy(obj, "doop");
             sinonSpy(obj, "foo");
 
@@ -1505,7 +1505,7 @@ describe("assert", function () {
 
         it("assert.calledWith match.instanceOf exception message", function () {
             this.obj.doSomething();
-            var matcher = sinonMatch.instanceOf(function CustomType() {});
+            var matcher = sinonMatch.instanceOf(function CustomType() { return; });
 
             assert.equals(
                 this.message("calledWith", this.obj.doSomething, matcher).replace(/ at.*/g, ""),
@@ -1553,7 +1553,7 @@ describe("assert", function () {
 
         it("assert.calledWith match test function exception message", function () {
             this.obj.doSomething();
-            var matcher = sinonMatch({ test: function custom() {} });
+            var matcher = sinonMatch({ test: function custom() { return; } });
 
             assert.equals(
                 this.message("calledWith", this.obj.doSomething, matcher).replace(/ at.*/g, ""),
@@ -1673,7 +1673,7 @@ describe("assert", function () {
             var obj = {};
 
             function setupSymbol(symbol) {
-                obj[symbol] = function () {};
+                obj[symbol] = function () { return; };
                 sinonSpy(obj, symbol);
             }
 
diff --git a/test/call-test.js b/test/call-test.js
index 29c5990ea..cd6a32bab 100644
--- a/test/call-test.js
+++ b/test/call-test.js
@@ -11,8 +11,8 @@ var refute = referee.refute;
 function spyCallSetUp() {
     this.thisValue = {};
     this.args = [{}, [], new Error(), 3];
-    this.returnValue = function () {};
-    this.call = sinonSpyCall(function () {}, this.thisValue,
+    this.returnValue = function () { return; };
+    this.call = sinonSpyCall(function () { return; }, this.thisValue,
         this.args, this.returnValue, null, 0);
 }
 
@@ -121,14 +121,14 @@ describe("sinonSpy.call", function () {
         });
 
         it("stores given call id", function () {
-            var call = sinonSpyCall(function () {}, {}, [], null, null, 42);
+            var call = sinonSpyCall(function () { return; }, {}, [], null, null, 42);
 
             assert.same(call.callId, 42);
         });
 
         it("throws if callId is undefined", function () {
             assert.exception(function () {
-                sinonSpyCall.create(function () {}, {}, []);
+                sinonSpyCall.create(function () { return; }, {}, []);
             });
         });
 
@@ -219,13 +219,13 @@ describe("sinonSpy.call", function () {
         });
 
         it("returns true for no arguments", function () {
-            var call = sinonSpyCall(function () {}, {}, [], null, null, 0);
+            var call = sinonSpyCall(function () { return; }, {}, [], null, null, 0);
 
             assert(call.calledWithExactly());
         });
 
         it("returns false when called with no args but matching one", function () {
-            var call = sinonSpyCall(function () {}, {}, [], null, null, 0);
+            var call = sinonSpyCall(function () { return; }, {}, [], null, null, 0);
 
             assert.isFalse(call.calledWithExactly({}));
         });
@@ -463,8 +463,8 @@ describe("sinonSpy.call", function () {
     describe(".callback", function () {
         it("it should be a reference for the callback", function () {
             var spy = sinonSpy();
-            var callback1 = function () {};
-            var callback2 = function () {};
+            var callback1 = function () { return; };
+            var callback2 = function () { return; };
 
             spy(1, 2, 3, callback1);
             assert.equals(spy.getCall(0).callback, callback1);
@@ -594,7 +594,7 @@ describe("sinonSpy.call", function () {
     describe("call.invokeCallback", function () {
 
         it("is alias for yield", function () {
-            var call = sinonSpyCall(function () {}, {}, [], null, null, 0);
+            var call = sinonSpyCall(function () { return; }, {}, [], null, null, 0);
 
             assert.same(call.yield, call.invokeCallback);
         });
@@ -1040,7 +1040,7 @@ describe("sinonSpy.call", function () {
 
     describe("constructor", function () {
         beforeEach(function () {
-            this.CustomConstructor = function () {};
+            this.CustomConstructor = function () { return; };
             this.customPrototype = this.CustomConstructor.prototype;
             sinonSpy(this, "CustomConstructor");
         });
@@ -1082,7 +1082,7 @@ describe("sinonSpy.call", function () {
         });
 
         it("haves toString method", function () {
-            var obj = { meth: function () {} };
+            var obj = { meth: function () { return; } };
             sinonSpy(obj, "meth");
 
             assert.equals(obj.meth.toString(), "meth");
@@ -1095,14 +1095,14 @@ describe("sinonSpy.call", function () {
         });
 
         it("toString should report name of spied function", function () {
-            function myTestFunc() {}
+            function myTestFunc() { return; }
             var spy = sinonSpy(myTestFunc);
 
             assert.equals(spy.toString(), "myTestFunc");
         });
 
         it("toString should prefer displayName property if available", function () {
-            function myTestFunc() {}
+            function myTestFunc() { return; }
             myTestFunc.displayName = "My custom method";
             var spy = sinonSpy(myTestFunc);
 
@@ -1389,11 +1389,11 @@ describe("sinonSpy.call", function () {
     describe(".printf", function () {
         describe("name", function () {
             it("named", function () {
-                var named = sinonSpy(function cool() { });
+                var named = sinonSpy(function cool() { return; });
                 assert.equals(named.printf("%n"), "cool");
             });
             it("anon", function () {
-                var anon = sinonSpy(function () {});
+                var anon = sinonSpy(function () { return; });
                 assert.equals(anon.printf("%n"), "spy");
 
                 var noFn = sinonSpy();
diff --git a/test/fake-test.js b/test/fake-test.js
index 850ef48c1..f0cc2d2c2 100644
--- a/test/fake-test.js
+++ b/test/fake-test.js
@@ -29,7 +29,7 @@ function verifyProxy(func, argument) {
     });
 }
 
-function noop() {}
+function noop() { return; }
 
 function requirePromiseSupport() {
     if (typeof Promise !== "function") {
@@ -50,7 +50,7 @@ describe("fake", function () {
     });
 
     describe("when passed a Function", function () {
-        verifyProxy(fake, function () {});
+        verifyProxy(fake, function () { return; });
 
         it("should keep the `this` context of the wrapped function", function () {
             function method() { return this.foo; }
@@ -81,8 +81,8 @@ describe("fake", function () {
     describe(".callback", function () {
         it("it should be a reference for the callback in the last call", function () {
             var f = fake();
-            var callback1 = function () {};
-            var callback2 = function () {};
+            var callback1 = function () { return; };
+            var callback2 = function () { return; };
 
             f(1, 2, 3, callback1);
             assert.equals(f.callback, callback1);
@@ -264,7 +264,7 @@ describe("fake", function () {
             var callback = sinon.spy();
             var myFake = fake.yields();
 
-            myFake(function () {}, callback);
+            myFake(function () { return; }, callback);
 
             sinon.assert.calledOnce(callback);
         });
@@ -273,7 +273,7 @@ describe("fake", function () {
             var myFake = fake.yields();
 
             assert.exception(function () {
-                myFake(function () {}, "not a function");
+                myFake(function () { return; }, "not a function");
             }, /TypeError: Expected last argument to be a function/);
         });
     });
@@ -301,7 +301,7 @@ describe("fake", function () {
             var callback = sinon.spy();
             var myFake = fake.yieldsAsync();
 
-            myFake(function () {}, callback);
+            myFake(function () { return; }, callback);
 
             sinon.assert.notCalled(callback);
 
@@ -316,7 +316,7 @@ describe("fake", function () {
             var myFake = fake.yieldsAsync();
 
             assert.exception(function () {
-                myFake(function () {}, "not a function");
+                myFake(function () { return; }, "not a function");
             }, /TypeError: Expected last argument to be a function/);
         });
     });
diff --git a/test/issues/issues-test.js b/test/issues/issues-test.js
index 3b5854510..d0b755320 100644
--- a/test/issues/issues-test.js
+++ b/test/issues/issues-test.js
@@ -75,8 +75,8 @@ describe("issues", function () {
 
     describe("#852 - createStubInstance on intherited constructors", function () {
         it("must not throw error", function () {
-            var A = function () {};
-            var B = function () {};
+            var A = function () { return; };
+            var B = function () { return; };
 
             B.prototype = Object.create(A.prototype);
             B.prototype.constructor = A;
@@ -89,7 +89,7 @@ describe("issues", function () {
 
     describe("#852(2) - createStubInstance should on same constructor", function () {
         it("must be idempotent", function () {
-            var A = function () {};
+            var A = function () { return; };
             refute.exception(function () {
                 sinon.createStubInstance(A);
                 sinon.createStubInstance(A);
@@ -98,7 +98,7 @@ describe("issues", function () {
     });
 
     describe("#950 - first execution of a spy as a method renames that spy", function () {
-        function bob() {}
+        function bob() { return; }
 
         // IE 11 does not support the function name property
         if (bob.name) {
@@ -144,11 +144,11 @@ describe("issues", function () {
                 oldWatch = Object.prototype.watch;
 
                 if (typeof Object.prototype.watch !== "function") {
-                    Object.prototype.watch = function rolex() {}; // eslint-disable-line no-extend-native
+                    Object.prototype.watch = function rolex() { return; }; // eslint-disable-line no-extend-native
                 }
 
                 var stubbedObject = sinon.stub({
-                    watch: function () {}
+                    watch: function () { return; }
                 });
 
                 stubbedObject.watch();
@@ -337,7 +337,7 @@ describe("issues", function () {
         });
 
         it("can stub methods on the prototype", function () {
-            var proto = { someFunction: function () {} };
+            var proto = { someFunction: function () { return; } };
             var instance = Object.create(proto);
 
             var stub = sandbox.stub(instance, "someFunction");
@@ -383,7 +383,7 @@ describe("issues", function () {
     describe("#1442 - callThrough with a mock expectation", function () {
         it("should call original method", function () {
             var foo = {
-                bar: function () { }
+                bar: function () { return; }
             };
 
             var mock = this.sandbox.mock(foo);
@@ -398,7 +398,7 @@ describe("issues", function () {
     describe("#1648 - resetHistory ", function () {
         it("should reset property spies", function () {
             var obj = {
-                func: function () {},
+                func: function () { return; },
                 get prop() {
                     return 1;
                 }
@@ -538,8 +538,8 @@ describe("issues", function () {
 
     describe("#1882", function () {
         it("should use constructor name when checking deepEquality", function () {
-            function ClassWithoutProps() {}
-            function AnotherClassWithoutProps() {}
+            function ClassWithoutProps() { return; }
+            function AnotherClassWithoutProps() { return; }
             ClassWithoutProps.prototype.constructor = ClassWithoutProps;
             AnotherClassWithoutProps.prototype.constructor = AnotherClassWithoutProps;
             var arg1 = new ClassWithoutProps(); //arg1.constructor.name === ClassWithoutProps
diff --git a/test/match-test.js b/test/match-test.js
index 8488833f0..295b613a2 100644
--- a/test/match-test.js
+++ b/test/match-test.js
@@ -69,7 +69,7 @@ function propertyMatcherTests(matcher, additionalTests) {
         it("compares with matcher", function () {
             var has = matcher("callback", sinonMatch.typeOf("function"));
 
-            assert(has.test({ callback: function () {} }));
+            assert(has.test({ callback: function () { return; } }));
         });
 
         if (typeof additionalTests === "function") {
@@ -80,13 +80,13 @@ function propertyMatcherTests(matcher, additionalTests) {
 
 describe("sinonMatch", function () {
     it("returns matcher", function () {
-        var match = sinonMatch(function () {});
+        var match = sinonMatch(function () { return; });
 
         assert(sinonMatch.isMatcher(match));
     });
 
     it("exposes test function", function () {
-        var test = function () {};
+        var test = function () { return; };
 
         var match = sinonMatch(test);
 
@@ -300,7 +300,7 @@ describe("sinonMatch", function () {
     });
 
     it("returns false if test function in object returns nothing", function () {
-        var match = sinonMatch({ test: function () {}});
+        var match = sinonMatch({ test: function () { return; }});
 
         assert.isFalse(match.test());
     });
@@ -323,13 +323,13 @@ describe("sinonMatch", function () {
         it("returns message", function () {
             var message = "hello sinonMatch";
 
-            var match = sinonMatch(function () {}, message);
+            var match = sinonMatch(function () { return; }, message);
 
             assert.same(match.toString(), message);
         });
 
         it("defaults to match(functionName)", function () {
-            var match = sinonMatch(function custom() {});
+            var match = sinonMatch(function custom() { return; });
 
             assert.same(match.toString(), "match(custom)");
         });
@@ -368,7 +368,7 @@ describe("sinonMatch", function () {
 
         it("returns true if test is called with any object", function () {
             assert(sinonMatch.defined.test({}));
-            assert(sinonMatch.defined.test(function () {}));
+            assert(sinonMatch.defined.test(function () { return; }));
         });
     });
 
@@ -459,7 +459,7 @@ describe("sinonMatch", function () {
                 [1, 2, 3],
                 ["a", "b", "c"],
                 [{ a: "a" }, { b: "b"}],
-                [function () {}, function () {}],
+                [function () { return; }, function () { return; }],
                 [null, undefined]
             ];
 
@@ -542,13 +542,13 @@ describe("sinonMatch", function () {
         if (typeof Symbol !== "undefined" && typeof Symbol.hasInstance !== "undefined") {
             it("does not throw if given argument defines Symbol.hasInstance", function () {
                 var objectWithCustomTypeChecks = {};
-                objectWithCustomTypeChecks[Symbol.hasInstance] = function () {};
+                objectWithCustomTypeChecks[Symbol.hasInstance] = function () { return; };
                 sinonMatch.instanceOf(objectWithCustomTypeChecks);
             });
         }
 
         it("returns matcher", function () {
-            var instanceOf = sinonMatch.instanceOf(function () {});
+            var instanceOf = sinonMatch.instanceOf(function () { return; });
 
             assert(sinonMatch.isMatcher(instanceOf));
         });
@@ -688,7 +688,7 @@ describe("sinonMatch", function () {
             refute(every.test(1));
             refute(every.test("a"));
             refute(every.test(null));
-            refute(every.test(function () {}));
+            refute(every.test(function () { return; }));
         });
 
         it("matches an object if the predicate is true for every property", function () {
@@ -767,7 +767,7 @@ describe("sinonMatch", function () {
             refute(some.test(1));
             refute(some.test("a"));
             refute(some.test(null));
-            refute(some.test(function () {}));
+            refute(some.test(function () { return; }));
         });
 
         it("matches an object if the predicate is true for some of the properties", function () {
diff --git a/test/mock-test.js b/test/mock-test.js
index 7d93ecabf..8eeb55a3f 100644
--- a/test/mock-test.js
+++ b/test/mock-test.js
@@ -36,7 +36,7 @@ describe("sinonMock", function () {
 
     describe(".expects", function () {
         beforeEach(function () {
-            this.mock = sinonMock.create({ someMethod: function () {} });
+            this.mock = sinonMock.create({ someMethod: function () { return; } });
         });
 
         it("throws without method", function () {
@@ -324,7 +324,7 @@ describe("sinonMock", function () {
             });
 
             it("should not throw when exceeding at least expectation", function () {
-                var obj = { foobar: function () {} };
+                var obj = { foobar: function () { return; } };
                 var mock = sinonMock(obj);
                 mock.expects("foobar").atLeast(1);
 
@@ -337,7 +337,7 @@ describe("sinonMock", function () {
             });
 
             it("should not throw when exceeding at least expectation and withargs", function () {
-                var obj = { foobar: function () {} };
+                var obj = { foobar: function () { return; } };
                 var mock = sinonMock(obj);
 
                 mock.expects("foobar").withArgs("arg1");
@@ -558,7 +558,7 @@ describe("sinonMock", function () {
 
             it("works with sinon matchers", function () {
                 this.expectation.withArgs(sinonMatch.number, sinonMatch.string, sinonMatch.func);
-                this.expectation(1, "test", function () {});
+                this.expectation(1, "test", function () { return; });
 
                 assert(this.expectation.met());
             });
@@ -710,7 +710,7 @@ describe("sinonMock", function () {
 
     describe(".verify", function () {
         beforeEach(function () {
-            this.method = function () {};
+            this.method = function () { return; };
             this.object = { method: this.method };
             this.mock = sinonMock.create(this.object);
         });
@@ -947,7 +947,7 @@ describe("sinonMock", function () {
 
     describe(".usingPromise", function () {
         beforeEach(function () {
-            this.method = function () {};
+            this.method = function () { return; };
             this.object = { method: this.method };
             this.mock = sinonMock.create(this.object);
         });
@@ -986,7 +986,7 @@ describe("sinonMock", function () {
 
     describe("mock object", function () {
         beforeEach(function () {
-            this.method = function () {};
+            this.method = function () { return; };
             this.object = { method: this.method };
             this.mock = sinonMock.create(this.object);
         });
@@ -1042,7 +1042,7 @@ describe("sinonMock", function () {
     describe("mock method multiple times", function () {
         beforeEach(function () {
             this.thisValue = {};
-            this.method = function () {};
+            this.method = function () { return; };
             this.object = { method: this.method };
             this.mock = sinonMock.create(this.object);
             this.mock.expects("method");
@@ -1077,7 +1077,7 @@ describe("sinonMock", function () {
         });
 
         it("allows mock calls in any order", function () {
-            var object = { method: function () {} };
+            var object = { method: function () { return; } };
             var mock = sinonMock(object);
             mock.expects("method").once().withArgs(42);
             mock.expects("method").twice().withArgs("Yeah");
diff --git a/test/sandbox-test.js b/test/sandbox-test.js
index b5c4399d8..3ba146880 100644
--- a/test/sandbox-test.js
+++ b/test/sandbox-test.js
@@ -36,7 +36,7 @@ referee.add("fakeServerWithClock", {
 });
 
 describe("Sandbox", function () {
-    function noop() {}
+    function noop() { return; }
 
     it("exposes match", function () {
         var sandbox = new Sandbox();
@@ -71,7 +71,7 @@ describe("Sandbox", function () {
         });
 
         it("returns a mock", function () {
-            var object = { method: function () { }};
+            var object = { method: function () { return; }};
 
             var actual = this.sandbox.mock(object);
             actual.expects("method");
@@ -82,7 +82,7 @@ describe("Sandbox", function () {
 
         it("adds mock to fake array", function () {
             var fakes = this.sandbox.getFakes();
-            var object = { method: function () { }};
+            var object = { method: function () { return; }};
             var expected = this.sandbox.mock(object);
 
             assert(fakes.indexOf(expected) !== -1);
@@ -106,8 +106,8 @@ describe("Sandbox", function () {
         it("appends mocks and stubs to fake array", function () {
             var fakes = this.sandbox.getFakes();
 
-            this.sandbox.mock({ method: function () {} }, "method");
-            this.sandbox.stub({ method: function () {} }, "method");
+            this.sandbox.mock({ method: function () { return; } }, "method");
+            this.sandbox.stub({ method: function () { return; } }, "method");
 
             assert.equals(fakes.length, 2);
         });
@@ -139,8 +139,8 @@ describe("Sandbox", function () {
         });
 
         it("stubs existing methods", function () {
-            var Class = function () {};
-            Class.prototype.method = function () {};
+            var Class = function () { return; };
+            Class.prototype.method = function () { return; };
 
             var stub = this.sandbox.createStubInstance(Class);
             stub.method.returns(3);
@@ -162,10 +162,10 @@ describe("Sandbox", function () {
         });
 
         it("resets all stub methods on reset()", function () {
-            var Class = function () {};
-            Class.prototype.method1 = function () {};
-            Class.prototype.method2 = function () {};
-            Class.prototype.method3 = function () {};
+            var Class = function () { return; };
+            Class.prototype.method1 = function () { return; };
+            Class.prototype.method2 = function () { return; };
+            Class.prototype.method3 = function () { return; };
 
             var stub = this.sandbox.createStubInstance(Class);
             stub.method1.returns(1);
@@ -181,7 +181,7 @@ describe("Sandbox", function () {
         });
 
         it("doesn't stub fake methods", function () {
-            var Class = function () {};
+            var Class = function () { return; };
 
             var stub = this.sandbox.createStubInstance(Class);
             assert.exception(function () {
@@ -194,7 +194,7 @@ describe("Sandbox", function () {
                 var c = a + b;
                 throw c;
             };
-            Class.prototype.method = function () {};
+            Class.prototype.method = function () { return; };
 
             var stub = this.sandbox.createStubInstance(Class);
             refute.exception(function () {
@@ -204,7 +204,7 @@ describe("Sandbox", function () {
 
         it("retains non function values", function () {
             var TYPE = "some-value";
-            var Class = function () {};
+            var Class = function () { return; };
             Class.prototype.type = TYPE;
 
             var stub = this.sandbox.createStubInstance(Class);
@@ -217,7 +217,7 @@ describe("Sandbox", function () {
                     throw "error";
                 }
             };
-            var Class = function () {};
+            var Class = function () { return; };
             Class.prototype = proto;
 
             var stub = this.sandbox.createStubInstance(Class);
@@ -272,7 +272,7 @@ describe("Sandbox", function () {
         });
 
         it("creates a stub", function () {
-            var object = { method: function () {} };
+            var object = { method: function () { return; } };
 
             this.sandbox.stub(object, "method");
 
@@ -281,7 +281,7 @@ describe("Sandbox", function () {
 
         it("adds stub to fake array", function () {
             var fakes = this.sandbox.getFakes();
-            var object = { method: function () {} };
+            var object = { method: function () { return; } };
             var stub = this.sandbox.stub(object, "method");
 
             assert.isTrue(fakes.indexOf(stub) !== -1);
@@ -290,8 +290,8 @@ describe("Sandbox", function () {
         it("appends stubs to fake array", function () {
             var fakes = this.sandbox.getFakes();
 
-            this.sandbox.stub({ method: function () {} }, "method");
-            this.sandbox.stub({ method: function () {} }, "method");
+            this.sandbox.stub({ method: function () { return; } }, "method");
+            this.sandbox.stub({ method: function () { return; } }, "method");
 
             assert.equals(fakes.length, 2);
         });
@@ -299,9 +299,9 @@ describe("Sandbox", function () {
         it("adds all object methods to fake array", function () {
             var fakes = this.sandbox.getFakes();
             var object = {
-                method: function () {},
-                method2: function () {},
-                method3: function () {}
+                method: function () { return; },
+                method2: function () { return; },
+                method3: function () { return; }
             };
 
             Object.defineProperty(object, "method3", {
@@ -317,12 +317,12 @@ describe("Sandbox", function () {
         });
 
         it("returns a stubbed object", function () {
-            var object = { method: function () {} };
+            var object = { method: function () { return; } };
             assert.equals(this.sandbox.stub(object), object);
         });
 
         it("returns a stubbed method", function () {
-            var object = { method: function () {} };
+            var object = { method: function () { return; } };
             assert.equals(this.sandbox.stub(object, "method"), object.method);
         });
 
@@ -334,7 +334,7 @@ describe("Sandbox", function () {
 
                 it("stubs environment property", function () {
                     var originalPrintWarning = deprecated.printWarning;
-                    deprecated.printWarning = function () {};
+                    deprecated.printWarning = function () { return; };
 
                     this.sandbox.stub(process.env, "HELL").value("froze over");
                     assert.equals(process.env.HELL, "froze over");
@@ -353,7 +353,7 @@ describe("Sandbox", function () {
 
         it("stubs number property", function () {
             var originalPrintWarning = deprecated.printWarning;
-            deprecated.printWarning = function () {};
+            deprecated.printWarning = function () { return; };
 
             this.sandbox.stub(this.object, "property").value(1);
 
@@ -364,7 +364,7 @@ describe("Sandbox", function () {
 
         it("restores number property", function () {
             var originalPrintWarning = deprecated.printWarning;
-            deprecated.printWarning = function () {};
+            deprecated.printWarning = function () { return; };
 
             this.sandbox.stub(this.object, "property").value(1);
             this.sandbox.restore();
@@ -376,7 +376,7 @@ describe("Sandbox", function () {
 
         it("fails if property does not exist", function () {
             var originalPrintWarning = deprecated.printWarning;
-            deprecated.printWarning = function () {};
+            deprecated.printWarning = function () { return; };
 
             var sandbox = this.sandbox;
             var object = {};
@@ -394,7 +394,7 @@ describe("Sandbox", function () {
                 var object = {};
 
                 var originalPrintWarning = deprecated.printWarning;
-                deprecated.printWarning = function () {};
+                deprecated.printWarning = function () { return; };
 
                 assert.exception(function () {
                     sandbox.stub(object, Symbol());
@@ -589,8 +589,8 @@ describe("Sandbox", function () {
         });
 
         it("should replace a function property", function () {
-            var replacement = function replacement() {};
-            var existing = function existing() {};
+            var replacement = function replacement() { return; };
+            var existing = function existing() { return; };
             var object = {
                 property: existing
             };
@@ -833,7 +833,7 @@ describe("Sandbox", function () {
         it("should error when descriptor has no getter", function () {
             var sandbox = this.sandbox;
             var object = { // eslint-disable-line accessor-pairs
-                set catpants(_) {}
+                set catpants(_) { return; }
             };
 
             assert.exception(
@@ -1028,7 +1028,7 @@ describe("Sandbox", function () {
             var sandbox = this.sandbox;
             // eslint-disable-next-line accessor-pairs
             var object = {
-                set foo(value) {}
+                set foo(value) { return; }
             };
 
             sandbox.replaceSetter(object, "foo", sinonFake());
@@ -1309,7 +1309,7 @@ describe("Sandbox", function () {
                 });
 
                 it("calls sinon.useFakeXMLHttpRequest", function () {
-                    var stubXhr = { restore: function () {} };
+                    var stubXhr = { restore: function () { return; } };
 
                     this.sandbox.stub(fakeXhr, "useFakeXMLHttpRequest").returns(stubXhr);
                     var returnedXhr = this.sandbox.useFakeXMLHttpRequest();
@@ -1319,14 +1319,14 @@ describe("Sandbox", function () {
                 });
 
                 it("returns fake xhr object created by nise", function () {
-                    this.sandbox.stub(fakeXhr, "useFakeXMLHttpRequest").returns({ restore: function () {} });
+                    this.sandbox.stub(fakeXhr, "useFakeXMLHttpRequest").returns({ restore: function () { return; } });
                     this.sandbox.useFakeXMLHttpRequest();
 
                     assert(fakeXhr.useFakeXMLHttpRequest.called);
                 });
 
                 it("doesn't secretly use useFakeServer", function () {
-                    this.sandbox.stub(fakeServer, "create").returns({ restore: function () {} });
+                    this.sandbox.stub(fakeServer, "create").returns({ restore: function () { return; } });
                     this.sandbox.useFakeXMLHttpRequest();
 
                     assert(fakeServer.create.notCalled);
@@ -1561,7 +1561,7 @@ describe("Sandbox", function () {
         });
 
         it("does not inject properties if they are already present", function () {
-            var server = function () {};
+            var server = function () { return; };
             var clock = {};
             var spy = false;
             var object = { server: server, clock: clock, spy: spy};
diff --git a/test/spy-test.js b/test/spy-test.js
index b94d76158..e6ff962ea 100644
--- a/test/spy-test.js
+++ b/test/spy-test.js
@@ -223,7 +223,7 @@ describe("spy", function () {
     });
 
     it("returns spy function", function () {
-        var func = function () {};
+        var func = function () { return; };
         var spy = createSpy.create(func);
 
         assert.isFunction(spy);
@@ -231,7 +231,7 @@ describe("spy", function () {
     });
 
     it("mirrors custom properties on function", function () {
-        var func = function () {};
+        var func = function () { return; };
         func.myProp = 42;
         var spy = createSpy.create(func);
 
@@ -245,7 +245,7 @@ describe("spy", function () {
     });
 
     it("does not overwrite original create property", function () {
-        var func = function () {};
+        var func = function () { return; };
         var object = func.create = {};
         var spy = createSpy.create(func);
 
@@ -380,8 +380,8 @@ describe("spy", function () {
         }
 
         var object = {
-            f1: function () {},
-            f2: function () {}
+            f1: function () { return; },
+            f2: function () { return; }
         };
 
         // f1: the order of withArgs(1), withArgs(1, 1)
@@ -440,7 +440,7 @@ describe("spy", function () {
         });
 
         it("passes 'new' to underlying function", function () {
-            function TestClass() {}
+            function TestClass() { return; }
 
             var SpyClass = createSpy.create(TestClass);
 
@@ -500,37 +500,39 @@ describe("spy", function () {
         });
 
         it("retains function length 0", function () {
-            var spy = createSpy.create(function () {});
+            var spy = createSpy.create(function () { return; });
 
             assert.equals(spy.length, 0);
         });
 
         it("retains function length 1", function () {
-            var spy = createSpy.create(function (a) {}); // eslint-disable-line no-unused-vars
+            var spy = createSpy.create(function (a) { return; }); // eslint-disable-line no-unused-vars
 
             assert.equals(spy.length, 1);
         });
 
         it("retains function length 2", function () {
-            var spy = createSpy.create(function (a, b) {}); // eslint-disable-line no-unused-vars
+            var spy = createSpy.create(function (a, b) { return; }); // eslint-disable-line no-unused-vars
 
             assert.equals(spy.length, 2);
         });
 
         it("retains function length 3", function () {
-            var spy = createSpy.create(function (a, b, c) {}); // eslint-disable-line no-unused-vars
+            var spy = createSpy.create(function (a, b, c) { return; }); // eslint-disable-line no-unused-vars
 
             assert.equals(spy.length, 3);
         });
 
         it("retains function length 4", function () {
-            var spy = createSpy.create(function (a, b, c, d) {}); // eslint-disable-line no-unused-vars
+            var spy = createSpy.create(function (a, b, c, d) { return; }); // eslint-disable-line no-unused-vars
 
             assert.equals(spy.length, 4);
         });
 
         it("retains function length 12", function () {
-            var func12Args = function (a, b, c, d, e, f, g, h, i, j, k, l) {}; // eslint-disable-line no-unused-vars
+            var func12Args = function (a, b, c, d, e, f, g, h, i, j, k, l) { // eslint-disable-line no-unused-vars
+                return;
+            };
             var spy = createSpy.create(func12Args);
 
             assert.equals(spy.length, 12);
@@ -828,7 +830,7 @@ describe("spy", function () {
         });
 
         it("is true if called with new on custom constructor", function () {
-            function MyThing() {}
+            function MyThing() { return; }
             MyThing.prototype = {};
             var ns = { MyThing: MyThing };
             createSpy(ns, "MyThing");
@@ -935,7 +937,7 @@ describe("spy", function () {
         });
 
         it("stacks up objects", function () {
-            function MyConstructor() {}
+            function MyConstructor() { return; }
             var objects = [{}, [], new MyConstructor(), { id: 243 }];
             this.spy();
             this.spy.call(objects[0]);
@@ -1530,7 +1532,7 @@ describe("spy", function () {
         });
 
         it("returns true when returned value once", function () {
-            var values = [{}, 2, "hey", function () {}];
+            var values = [{}, 2, "hey", function () { return; }];
             var spy = createSpy.create(function () {
                 return values[spy.callCount];
             });
@@ -1544,7 +1546,7 @@ describe("spy", function () {
         });
 
         it("returns false when value is never returned", function () {
-            var values = [{}, 2, "hey", function () {}];
+            var values = [{}, 2, "hey", function () { return; }];
             var spy = createSpy.create(function () {
                 return values[spy.callCount];
             });
@@ -1627,7 +1629,7 @@ describe("spy", function () {
         });
 
         it("contains the created object for spied constructors", function () {
-            var Spy = createSpy.create(function () { });
+            var Spy = createSpy.create(function () { return; });
 
             var result = new Spy();
 
@@ -2126,7 +2128,7 @@ describe("spy", function () {
         });
 
         it("includes spy name in error message", function () {
-            var api = { someMethod: function () {} };
+            var api = { someMethod: function () { return; } };
             var spy = createSpy(api, "someMethod");
 
             assert.exception(
@@ -2225,7 +2227,7 @@ describe("spy", function () {
         });
 
         it("includes spy name in error message", function () {
-            var api = { someMethod: function () {} };
+            var api = { someMethod: function () { return; } };
             var spy = createSpy(api, "someMethod");
             var thisObj = { name1: "value1", name2: "value2" };
 
@@ -2332,7 +2334,7 @@ describe("spy", function () {
         });
 
         it("includes spy name in error message", function () {
-            var api = { someMethod: function () {} };
+            var api = { someMethod: function () { return; } };
             var spy = createSpy(api, "someMethod");
 
             assert.exception(
@@ -2420,7 +2422,7 @@ describe("spy", function () {
         });
 
         it("includes spy name in error message", function () {
-            var api = { someMethod: function () {} };
+            var api = { someMethod: function () { return; } };
             var spy = createSpy(api, "someMethod");
             var thisObj = { name1: "value1", name2: "value2" };
 
@@ -2501,7 +2503,7 @@ describe("spy", function () {
         });
 
         it("includes spy name in error message", function () {
-            var api = { someMethod: function () {} };
+            var api = { someMethod: function () { return; } };
             var spy = createSpy(api, "someMethod");
 
             assert.exception(
@@ -2596,7 +2598,7 @@ describe("spy", function () {
         });
 
         it("includes spy name in error message", function () {
-            var api = { someMethod: function () {} };
+            var api = { someMethod: function () { return; } };
             var spy = createSpy(api, "someMethod");
             var thisObj = { name1: "value1", name2: "value2" };
 
@@ -2738,7 +2740,7 @@ describe("spy", function () {
         });
 
         it("matches the function length", function () {
-            var api = { someMethod: function (a, b, c) {} }; // eslint-disable-line no-unused-vars
+            var api = { someMethod: function (a, b, c) { return; } }; // eslint-disable-line no-unused-vars
             var spy = createSpy(api, "someMethod");
 
             assert.equals(spy.length, 3);
diff --git a/test/stub-test.js b/test/stub-test.js
index 0fcea0333..2cc188fa8 100644
--- a/test/stub-test.js
+++ b/test/stub-test.js
@@ -1120,7 +1120,7 @@ describe("stub", function () {
 
     describe(".objectMethod", function () {
         beforeEach(function () {
-            this.method = function () {};
+            this.method = function () { return; };
             this.object = { method: this.method };
         });
 
@@ -1181,7 +1181,7 @@ describe("stub", function () {
         });
 
         it("successfully stubs falsey properties", function () {
-            var obj = { 0: function () { } };
+            var obj = { 0: function () { return; } };
 
             createStub(obj, 0).callsFake(function () {
                 return "stubbed value";
@@ -1192,7 +1192,7 @@ describe("stub", function () {
 
         it("does not stub function object", function () {
             assert.exception(function () {
-                createStub(function () {});
+                createStub(function () { return; });
             });
         });
     });
@@ -1200,9 +1200,9 @@ describe("stub", function () {
     describe("everything", function () {
         it("stubs all methods of object without property", function () {
             var obj = {
-                func1: function () {},
-                func2: function () {},
-                func3: function () {}
+                func1: function () { return; },
+                func2: function () { return; },
+                func3: function () { return; }
             };
 
             createStub(obj);
@@ -1213,8 +1213,8 @@ describe("stub", function () {
         });
 
         it("stubs prototype methods", function () {
-            function Obj() {}
-            Obj.prototype.func1 = function () {};
+            function Obj() { return; }
+            Obj.prototype.func1 = function () { return; };
             var obj = new Obj();
 
             createStub(obj);
@@ -1237,12 +1237,12 @@ describe("stub", function () {
 
         it("handles non-enumerable properties", function () {
             var obj = {
-                func1: function () {},
-                func2: function () {}
+                func1: function () { return; },
+                func2: function () { return; }
             };
 
             Object.defineProperty(obj, "func3", {
-                value: function () {},
+                value: function () { return; },
                 writable: true,
                 configurable: true
             });
@@ -1255,9 +1255,9 @@ describe("stub", function () {
         });
 
         it("handles non-enumerable properties on prototypes", function () {
-            function Obj() {}
+            function Obj() { return; }
             Object.defineProperty(Obj.prototype, "func1", {
-                value: function () {},
+                value: function () { return; },
                 writable: true,
                 configurable: true
             });
@@ -1281,10 +1281,10 @@ describe("stub", function () {
 
         it("does not fail on overrides", function () {
             var parent = {
-                func: function () {}
+                func: function () { return; }
             };
             var child = Object.create(parent);
-            child.func = function () {};
+            child.func = function () { return; };
 
             refute.exception(function () {
                 createStub(child);
@@ -1320,7 +1320,7 @@ describe("stub", function () {
 
     describe("stubbed function", function () {
         it("has toString method", function () {
-            var obj = { meth: function () {} };
+            var obj = { meth: function () { return; } };
             createStub(obj, "meth");
 
             assert.equals(obj.meth.toString(), "meth");
@@ -1360,7 +1360,7 @@ describe("stub", function () {
         });
 
         it("includes stub name and actual arguments in error", function () {
-            var myObj = { somethingAwesome: function () {} };
+            var myObj = { somethingAwesome: function () { return; } };
             var stub = createStub(myObj, "somethingAwesome").yields();
 
             assert.exception(
@@ -1476,7 +1476,7 @@ describe("stub", function () {
         });
 
         it("includes stub name and actual arguments in error", function () {
-            var myObj = { somethingAwesome: function () {} };
+            var myObj = { somethingAwesome: function () { return; } };
             var stub = createStub(myObj, "somethingAwesome").yieldsRight();
 
             assert.exception(
@@ -1605,7 +1605,7 @@ describe("stub", function () {
         });
 
         it("includes stub name and actual arguments in error", function () {
-            var myObj = { somethingAwesome: function () {} };
+            var myObj = { somethingAwesome: function () { return; } };
             var stub = createStub(myObj, "somethingAwesome").yieldsOn(this.fakeContext);
 
             assert.exception(
@@ -1743,7 +1743,7 @@ describe("stub", function () {
         });
 
         it("includes stub name and actual arguments in error", function () {
-            var myObj = { somethingAwesome: function () {} };
+            var myObj = { somethingAwesome: function () { return; } };
             var stub = createStub(myObj, "somethingAwesome").yieldsTo("success");
 
             assert.exception(
@@ -1890,7 +1890,7 @@ describe("stub", function () {
         });
 
         it("includes stub name and actual arguments in error", function () {
-            var myObj = { somethingAwesome: function () {} };
+            var myObj = { somethingAwesome: function () { return; } };
             var stub = createStub(myObj, "somethingAwesome").yieldsToOn("success", this.fakeContext);
 
             assert.exception(
@@ -2493,7 +2493,7 @@ describe("stub", function () {
 
     describe(".reset", function () {
         it("resets behavior", function () {
-            var obj = { a: function () {} };
+            var obj = { a: function () { return; } };
             var spy = createSpy();
             createStub(obj, "a").callsArg(1);
 
@@ -2683,7 +2683,7 @@ describe("stub", function () {
         });
 
         it("matches the function length", function () {
-            var api = { someMethod: function (a, b, c) {} }; // eslint-disable-line no-unused-vars
+            var api = { someMethod: function (a, b, c) { return; } }; // eslint-disable-line no-unused-vars
             var stub = createStub(api, "someMethod");
 
             assert.equals(stub.length, 3);
@@ -2692,8 +2692,8 @@ describe("stub", function () {
 
     describe(".createStubInstance", function () {
         it("stubs existing methods", function () {
-            var Class = function () {};
-            Class.prototype.method = function () {};
+            var Class = function () { return; };
+            Class.prototype.method = function () { return; };
 
             var stub = createStubInstance(Class);
             stub.method.returns(3);
@@ -2701,7 +2701,7 @@ describe("stub", function () {
         });
 
         it("doesn't stub fake methods", function () {
-            var Class = function () {};
+            var Class = function () { return; };
 
             var stub = createStubInstance(Class);
             assert.exception(function () {
@@ -2714,7 +2714,7 @@ describe("stub", function () {
                 var c = a + b;
                 throw c;
             };
-            Class.prototype.method = function () {};
+            Class.prototype.method = function () { return; };
 
             var stub = createStubInstance(Class);
             refute.exception(function () {
@@ -2724,7 +2724,7 @@ describe("stub", function () {
 
         it("retains non function values", function () {
             var TYPE = "some-value";
-            var Class = function () {};
+            var Class = function () { return; };
             Class.prototype.type = TYPE;
 
             var stub = createStubInstance(Class);
@@ -2737,7 +2737,7 @@ describe("stub", function () {
                     throw "error";
                 }
             };
-            var Class = function () {};
+            var Class = function () { return; };
             Class.prototype = proto;
 
             var stub = createStubInstance(Class);
@@ -2758,8 +2758,8 @@ describe("stub", function () {
         });
 
         it("allows providing optional overrides", function () {
-            var Class = function () {};
-            Class.prototype.method = function () {};
+            var Class = function () { return; };
+            Class.prototype.method = function () { return; };
 
             var stub = createStubInstance(Class, {
                 method: createStub().returns(3)
@@ -2769,8 +2769,8 @@ describe("stub", function () {
         });
 
         it("allows providing optional returned values", function () {
-            var Class = function () {};
-            Class.prototype.method = function () {};
+            var Class = function () { return; };
+            Class.prototype.method = function () { return; };
 
             var stub = createStubInstance(Class, {
                 method: 3
@@ -2780,8 +2780,8 @@ describe("stub", function () {
         });
 
         it("throws an exception when trying to override non-existing property", function () {
-            var Class = function () {};
-            Class.prototype.method = function () {};
+            var Class = function () { return; };
+            Class.prototype.method = function () { return; };
 
             assert.exception(function () {
                 createStubInstance(Class, {
@@ -3073,7 +3073,7 @@ describe("stub", function () {
         });
 
         it("allows stubbing function static properties", function () {
-            var myFunc = function () {};
+            var myFunc = function () { return; };
             myFunc.prop = "rawString";
 
             createStub(myFunc, "prop").value("newString");
@@ -3081,7 +3081,7 @@ describe("stub", function () {
         });
 
         it("allows restoring function static properties", function () {
-            var myFunc = function () {};
+            var myFunc = function () { return; };
             myFunc.prop = "rawString";
 
             var stub = createStub(myFunc, "prop").value("newString");
diff --git a/test/util/core/called-in-order-test.js b/test/util/core/called-in-order-test.js
index a19df7918..4d99a2f84 100644
--- a/test/util/core/called-in-order-test.js
+++ b/test/util/core/called-in-order-test.js
@@ -5,9 +5,9 @@ var calledInOrder = require("../../../lib/sinon/util/core/called-in-order");
 var sinonStub = require("../../../lib/sinon/stub");
 var assert = referee.assert;
 
-var testObject1 = {someFunction: function () {}};
-var testObject2 = {otherFunction: function () {}};
-var testObject3 = {thirdFunction: function () {}};
+var testObject1 = {someFunction: function () { return; }};
+var testObject2 = {otherFunction: function () { return; }};
+var testObject3 = {thirdFunction: function () { return; }};
 
 function testMethod() {
     testObject1.someFunction();
diff --git a/test/util/core/deep-equal-test.js b/test/util/core/deep-equal-test.js
index 65d16863c..7a9426a63 100644
--- a/test/util/core/deep-equal-test.js
+++ b/test/util/core/deep-equal-test.js
@@ -46,7 +46,7 @@ describe("util/core/deepEqual", function () {
     });
 
     it("passes same function", function () {
-        var func = function () {};
+        var func = function () { return; };
 
         assert(deepEqual(func, func));
     });
@@ -245,7 +245,7 @@ describe("util/core/deepEqual", function () {
     }
 
     it("passes deep objects", function () {
-        var func = function () {};
+        var func = function () { return; };
 
         var obj1 = {
             a: 1,
diff --git a/test/util/core/function-to-string-test.js b/test/util/core/function-to-string-test.js
index 8ee68daf3..91433ffff 100644
--- a/test/util/core/function-to-string-test.js
+++ b/test/util/core/function-to-string-test.js
@@ -7,7 +7,7 @@ var assert = referee.assert;
 
 describe("util/core/functionToString", function () {
     it("returns function's displayName property", function () {
-        var fn = function () {};
+        var fn = function () { return; };
         fn.displayName = "Larry";
 
         assert.equals(functionToString.call(fn), "Larry");
diff --git a/test/util/core/get-next-tick-test.js b/test/util/core/get-next-tick-test.js
index 90efe66d4..3c0a90ba1 100644
--- a/test/util/core/get-next-tick-test.js
+++ b/test/util/core/get-next-tick-test.js
@@ -7,14 +7,14 @@ var assert = referee.assert;
 describe("util/core/get-next-tick", function () {
     it("should use process.nextTick when available", function () {
         var mockProcess = {
-            nextTick: function () {}
+            nextTick: function () { return; }
         };
 
         assert.same(getNextTick(mockProcess), mockProcess.nextTick);
     });
 
     it("should use setImmediate when process.nextTick is not available", function () {
-        function mockSetImmediate() {}
+        function mockSetImmediate() { return; }
 
         assert.same(getNextTick(undefined, mockSetImmediate), mockSetImmediate);
     });
diff --git a/test/util/core/restore-test.js b/test/util/core/restore-test.js
index 2f971567c..8e33635b5 100644
--- a/test/util/core/restore-test.js
+++ b/test/util/core/restore-test.js
@@ -7,9 +7,9 @@ var assert = referee.assert;
 
 describe("util/core/restore", function () {
     it("restores all methods of supplied object", function () {
-        var methodA = function () {};
-        var methodB = function () {};
-        var nonEnumerableMethod = function () {};
+        var methodA = function () { return; };
+        var methodB = function () { return; };
+        var nonEnumerableMethod = function () { return; };
         var obj = { methodA: methodA, methodB: methodB, nonEnumerableMethod: nonEnumerableMethod };
         Object.defineProperty(obj, "nonEnumerableMethod", {
             enumerable: false
@@ -24,8 +24,8 @@ describe("util/core/restore", function () {
     });
 
     it("only restores restorable methods", function () {
-        var stubbedMethod = function () {};
-        var vanillaMethod = function () {};
+        var stubbedMethod = function () { return; };
+        var vanillaMethod = function () { return; };
         var obj = { stubbedMethod: stubbedMethod, vanillaMethod: vanillaMethod };
 
         createStub(obj, "stubbedMethod");
@@ -35,7 +35,7 @@ describe("util/core/restore", function () {
     });
 
     it("restores a single stubbed method", function () {
-        var method = function () {};
+        var method = function () { return; };
         var obj = { method: method };
 
         createStub(obj);
diff --git a/test/util/core/typeOf-test.js b/test/util/core/typeOf-test.js
index 458cf5b9b..e9f93fe21 100644
--- a/test/util/core/typeOf-test.js
+++ b/test/util/core/typeOf-test.js
@@ -22,7 +22,7 @@ describe("typeOf", function () {
     });
 
     it("returns function", function () {
-        assert.equals(sinonTypeOf(function () {}), "function");
+        assert.equals(sinonTypeOf(function () { return; }), "function");
     });
 
     it("returns undefined", function () {
diff --git a/test/util/core/walk-test.js b/test/util/core/walk-test.js
index d81d63bf5..f8f3f1332 100644
--- a/test/util/core/walk-test.js
+++ b/test/util/core/walk-test.js
@@ -85,7 +85,7 @@ describe("util/core/walk", function () {
     });
 
     it("should not invoke getters on the original receiving object", function () {
-        var Target = function Target() {};
+        var Target = function Target() { return; };
         var getter = createSpy();
         Object.defineProperty(Target.prototype, "computedFoo", {
             enumerable: true,
@@ -141,10 +141,10 @@ describe("util/core/walk", function () {
 
     it("does not walk the same property twice", function () {
         var parent = {
-            func: function parentFunc() {}
+            func: function parentFunc() { return; }
         };
         var child = Object.create(parent);
-        child.func = function childFunc() {};
+        child.func = function childFunc() { return; };
         var iterator = createSpy();
 
         walk(child, iterator);
diff --git a/test/util/core/wrap-method-test.js b/test/util/core/wrap-method-test.js
index cccb1f604..b428e293d 100644
--- a/test/util/core/wrap-method-test.js
+++ b/test/util/core/wrap-method-test.js
@@ -9,9 +9,9 @@ var refute = referee.refute;
 
 describe("util/core/wrapMethod", function () {
     beforeEach(function () {
-        this.method = function () {};
-        this.getter = function () {};
-        this.setter = function () {};
+        this.method = function () { return; };
+        this.getter = function () { return; };
+        this.setter = function () { return; };
         this.object = {method: this.method};
         Object.defineProperty(this.object, "property", {
             get: this.getter,
@@ -35,7 +35,7 @@ describe("util/core/wrapMethod", function () {
         var object = this.object;
 
         assert.exception(function () {
-            wrapMethod(object, "prop", function () {});
+            wrapMethod(object, "prop", function () { return; });
         }, {name: "TypeError"});
     });
 
@@ -46,7 +46,7 @@ describe("util/core/wrapMethod", function () {
             object[symbol] = 42;
 
             assert.exception(function () {
-                wrapMethod(object, symbol, function () {});
+                wrapMethod(object, symbol, function () { return; });
             }, function (err) {
                 return err.message === "Attempted to wrap number property Symbol() as function";
             });
@@ -57,12 +57,12 @@ describe("util/core/wrapMethod", function () {
         var object = this.object;
 
         assert.exception(function () {
-            wrapMethod(object, "prop", function () {});
+            wrapMethod(object, "prop", function () { return; });
         });
 
         assert.exception(
             function () {
-                wrapMethod(object, "prop", function () {});
+                wrapMethod(object, "prop", function () { return; });
             },
             {
                 message: /Attempted to wrap .* property .* as function/
@@ -87,14 +87,14 @@ describe("util/core/wrapMethod", function () {
     });
 
     it("replaces object method", function () {
-        wrapMethod(this.object, "method", function () {});
+        wrapMethod(this.object, "method", function () { return; });
 
         refute.same(this.method, this.object.method);
         assert.isFunction(this.object.method);
     });
 
     it("replaces getter", function () {
-        wrapMethod(this.object, "property", { get: function () {} });
+        wrapMethod(this.object, "property", { get: function () { return; } });
 
         refute.same(this.getter, Object.getOwnPropertyDescriptor(this.object, "property").get);
         assert.isFunction(Object.getOwnPropertyDescriptor(this.object, "property").get);
@@ -102,7 +102,7 @@ describe("util/core/wrapMethod", function () {
 
     it("replaces setter", function () {
         wrapMethod(this.object, "property", { // eslint-disable-line accessor-pairs
-            set: function () {}
+            set: function () { return; }
         });
 
         refute.same(this.setter, Object.getOwnPropertyDescriptor(this.object, "property").set);
@@ -110,10 +110,10 @@ describe("util/core/wrapMethod", function () {
     });
 
     it("throws if method is already wrapped", function () {
-        wrapMethod(this.object, "method", function () {});
+        wrapMethod(this.object, "method", function () { return; });
 
         assert.exception(function () {
-            wrapMethod(this.object, "method", function () {});
+            wrapMethod(this.object, "method", function () { return; });
         }, {name: "TypeError"});
     });
 
@@ -121,11 +121,11 @@ describe("util/core/wrapMethod", function () {
         if (typeof Symbol === "function") {
             var symbol = Symbol();
             var object = {};
-            object[symbol] = function () {};
-            wrapMethod(object, symbol, function () {});
+            object[symbol] = function () { return; };
+            wrapMethod(object, symbol, function () { return; });
 
             assert.exception(function () {
-                wrapMethod(object, symbol, function () {});
+                wrapMethod(object, symbol, function () { return; });
             }, function (err) {
                 return err.message === "Attempted to wrap Symbol() which is already wrapped";
             });
@@ -133,10 +133,10 @@ describe("util/core/wrapMethod", function () {
     });
 
     it("throws if property descriptor is already wrapped", function () {
-        wrapMethod(this.object, "property", { get: function () {} });
+        wrapMethod(this.object, "property", { get: function () { return; } });
 
         assert.exception(function () {
-            wrapMethod(this.object, "property", { get: function () {} });
+            wrapMethod(this.object, "property", { get: function () { return; } });
         }, {name: "TypeError"});
     });
 
@@ -144,7 +144,7 @@ describe("util/core/wrapMethod", function () {
         var object = { method: createSpy() };
 
         assert.exception(function () {
-            wrapMethod(object, "method", function () {});
+            wrapMethod(object, "method", function () { return; });
         }, {name: "TypeError"});
     });
 
@@ -155,7 +155,7 @@ describe("util/core/wrapMethod", function () {
             object[symbol] = createSpy();
 
             assert.exception(function () {
-                wrapMethod(object, symbol, function () {});
+                wrapMethod(object, symbol, function () { return; });
             }, function (err) {
                 return err.message === "Attempted to wrap Symbol() which is already spied on";
             });
@@ -183,14 +183,14 @@ describe("util/core/wrapMethod", function () {
         });
 
         it("throws with stack trace showing original wrapMethod call", function () {
-            var object = { method: function () {} };
+            var object = { method: function () { return; } };
             wrapMethod(object, "method", function () {
                 return "original";
             });
 
             assert.exception(
                 function () {
-                    wrapMethod(object, "method", function () {});
+                    wrapMethod(object, "method", function () { return; });
                 },
                 {
                     stack: ":STACK2:\n--------------\n:STACK1:"
@@ -202,25 +202,25 @@ describe("util/core/wrapMethod", function () {
     if (typeof window !== "undefined") {
         describe("in browser", function () {
             it("does not throw if object is window object", function () {
-                window.sinonTestMethod = function () {};
+                window.sinonTestMethod = function () { return; };
                 refute.exception(function () {
-                    wrapMethod(window, "sinonTestMethod", function () {});
+                    wrapMethod(window, "sinonTestMethod", function () { return; });
                 });
             });
         });
     }
 
     it("mirrors function properties", function () {
-        var object = { method: function () {} };
+        var object = { method: function () { return; } };
         object.method.prop = 42;
 
-        wrapMethod(object, "method", function () {});
+        wrapMethod(object, "method", function () { return; });
 
         assert.equals(object.method.prop, 42);
     });
 
     it("does not mirror and overwrite existing properties", function () {
-        var object = { method: function () {} };
+        var object = { method: function () { return; } };
         object.method.called = 42;
 
         createStub(object, "method");
@@ -230,24 +230,24 @@ describe("util/core/wrapMethod", function () {
 
     describe("wrapped method", function () {
         beforeEach(function () {
-            this.method = function () {};
+            this.method = function () { return; };
             this.object = { method: this.method };
         });
 
         it("defines restore method", function () {
-            wrapMethod(this.object, "method", function () {});
+            wrapMethod(this.object, "method", function () { return; });
 
             assert.isFunction(this.object.method.restore);
         });
 
         it("returns wrapper", function () {
-            var wrapper = wrapMethod(this.object, "method", function () {});
+            var wrapper = wrapMethod(this.object, "method", function () { return; });
 
             assert.same(this.object.method, wrapper);
         });
 
         it("restore brings back original method", function () {
-            wrapMethod(this.object, "method", function () {});
+            wrapMethod(this.object, "method", function () { return; });
             this.object.method.restore();
 
             assert.same(this.object.method, this.method);
@@ -256,21 +256,21 @@ describe("util/core/wrapMethod", function () {
 
     describe("wrapped prototype method", function () {
         beforeEach(function () {
-            this.type = function () {};
-            this.type.prototype.method = function () {};
+            this.type = function () { return; };
+            this.type.prototype.method = function () { return; };
 
             this.object = new this.type(); //eslint-disable-line new-cap
         });
 
         it("wrap adds owned property", function () {
-            var wrapper = wrapMethod(this.object, "method", function () {});
+            var wrapper = wrapMethod(this.object, "method", function () { return; });
 
             assert.same(this.object.method, wrapper);
             assert(this.object.hasOwnProperty("method"));
         });
 
         it("restore removes owned property", function () {
-            wrapMethod(this.object, "method", function () {});
+            wrapMethod(this.object, "method", function () { return; });
             this.object.method.restore();
 
             assert.same(this.object.method, this.type.prototype.method);
diff --git a/test/util/fake-timers-test.js b/test/util/fake-timers-test.js
index be7151cda..7df6685e5 100644
--- a/test/util/fake-timers-test.js
+++ b/test/util/fake-timers-test.js
@@ -103,7 +103,7 @@ describe("fakeTimers.clock", function () {
         });
 
         it("returns numeric id or object with numeric id", function () {
-            var result = this.clock.setImmediate(function () { });
+            var result = this.clock.setImmediate(function () { return; });
 
             if (typeof result === "object") {
                 assert.isNumber(result.id);
@@ -639,8 +639,8 @@ describe("fakeTimers.clock", function () {
             var realDate = new Date();
 
             // eslint-disable-next-line no-global-assign
-            Date = function () {};
-            this.global.Date = function () {};
+            Date = function () { return; };
+            this.global.Date = function () { return; };
 
             var date = new this.clock.Date();
 
@@ -892,7 +892,7 @@ describe("fakeTimers.clock", function () {
 
             var to = setTimeout(stub, 1000);
 
-            if (typeof (setTimeout(function () {}, 0)) === "object") {
+            if (typeof (setTimeout(function () { return; }, 0)) === "object") {
                 assert.isNumber(to.id);
                 assert.isFunction(to.ref);
                 assert.isFunction(to.unref);
@@ -976,7 +976,7 @@ describe("fakeTimers.clock", function () {
             it("deletes global property on restore if it was inherited onto the global object", function () {
                 // Give the global object an inherited 'tick' method
                 delete this.global.tick;
-                this.global.__proto__.tick = function () { };
+                this.global.__proto__.tick = function () { return; };
 
                 if (!this.global.hasOwnProperty("tick")) {
                     this.clock = fakeTimers.useFakeTimers({toFake: ["tick"]});
@@ -995,7 +995,7 @@ describe("fakeTimers.clock", function () {
 
         it("restores global property on restore if it is present on the global object itself", function () {
             // Directly give the global object a tick method
-            this.global.tick = function () { };
+            this.global.tick = function () { return; };
 
             this.clock = fakeTimers.useFakeTimers({toFake: ["tick"]});
             assert.isTrue(this.global.hasOwnProperty("tick"));
@@ -1021,7 +1021,7 @@ describe("fakeTimers.clock", function () {
         });
 
         it("decide on Date.now support at call-time when supported", function () {
-            this.global.Date.now = function () {};
+            this.global.Date.now = function () { return; };
             this.clock = fakeTimers.useFakeTimers(0);
 
             assert.equals(typeof Date.now, "function");
@@ -1035,7 +1035,7 @@ describe("fakeTimers.clock", function () {
         });
 
         it("mirrors custom Date properties", function () {
-            var f = function () { };
+            var f = function () { return; };
             this.global.Date.format = f;
             fakeTimers.useFakeTimers();