Warn the user if the minimum coverage is set greater than 100

CHANGELOG.md

@@ -1,3 +1,10 @@
+Unrealeased
+===================
+
+## Enhancements
+
+* If the minimum coverage is set to be greater than 100, a warning will be shown. See [#737](https://github.com/colszowka/simplecov/pull/737)
+
 0.17.0 (2019-07-02)
 ===================
 

lib/simplecov/configuration.rb

@@ -224,6 +224,7 @@ def merge_timeout(seconds = nil)
     # Default is 0% (disabled)
     #
     def minimum_coverage(coverage = nil)
+      minimum_possible_coverage_exceeded("minimum_coverage") if coverage && coverage > 100
       @minimum_coverage ||= (coverage || 0).to_f.round(2)
     end
 
@@ -245,6 +246,7 @@ def maximum_coverage_drop(coverage_drop = nil)
     # Default is 0% (disabled)
     #
     def minimum_coverage_by_file(coverage = nil)
+      minimum_possible_coverage_exceeded("minimum_coverage_by_file") if coverage && coverage > 100
       @minimum_coverage_by_file ||= (coverage || 0).to_f.round(2)
     end
 
@@ -288,6 +290,10 @@ def add_group(group_name, filter_argument = nil, &filter_proc)
 
   private
 
+    def minimum_possible_coverage_exceeded(coverage_option)
+      warn "The coverage you set for #{coverage_option} is greater than 100%"
+    end
+
     #
     # The actual filter processor. Not meant for direct use
     #

spec/configuration_spec.rb

@@ -33,5 +33,29 @@
         expect(config.tracked_files).to be_nil
       end
     end
+
+    describe "#minimum_coverage" do
+      it "does not warn you about your usage" do
+        expect(config).not_to receive(:warn)
+        config.minimum_coverage(100.00)
+      end
+
+      it "warns you about your usage" do
+        expect(config).to receive(:warn).with("The coverage you set for minimum_coverage is greater than 100%")
+        config.minimum_coverage(100.01)
+      end
+    end
+
+    describe "minimum_coverage_by_file" do
+      it "does not warn you about your usage" do
+        expect(config).not_to receive(:warn)
+        config.minimum_coverage_by_file(100.00)
+      end
+
+      it "warns you about your usage" do
+        expect(config).to receive(:warn).with("The coverage you set for minimum_coverage_by_file is greater than 100%")
+        config.minimum_coverage_by_file(100.01)
+      end
+    end
   end
 end