[OpenAPI Normalizer] update SIMPLIFY_ONEOF_ANYOF to convert enum of null to nullable (#14898)

* reorganize openapi normalizer tests

* add the logic to simply oneof anyof rule instead

* minor fix

Author: wing328

docs/customization.md

@@ -485,7 +485,7 @@ Example:
 java -jar modules/openapi-generator-cli/target/openapi-generator-cli.jar generate -g java -i modules/openapi-generator/src/test/resources/3_0/simplifyBooleanEnum_test.yaml -o /tmp/java-okhttp/ --openapi-normalizer SIMPLIFY_BOOLEAN_ENUM=true
 ```
 
-- `SIMPLIFY_ONEOF_ANYOF`: when set to `true`, simplify oneOf/anyOf by 1) removing null (sub-schema) and setting nullable to true instead, and 2) simplifying oneOf/anyOf with a single sub-schema to just the sub-schema itself.
+- `SIMPLIFY_ONEOF_ANYOF`: when set to `true`, simplify oneOf/anyOf by 1) removing null (sub-schema) or enum of null (sub-schema) and setting nullable to true instead, and 2) simplifying oneOf/anyOf with a single sub-schema to just the sub-schema itself.
 
 Example:
 ```

modules/openapi-generator/src/main/java/org/openapitools/codegen/OpenAPINormalizer.java

@@ -65,6 +65,7 @@ public class OpenAPINormalizer {
 
     // when set to true, oneOf/anyOf schema with only one sub-schema is simplified to just the sub-schema
     // and if sub-schema contains "null", remove it and set nullable to true instead
+    // and if sub-schema contains enum of "null", remove it and set nullable to true instead
     final String SIMPLIFY_ONEOF_ANYOF = "SIMPLIFY_ONEOF_ANYOF";
     boolean simplifyOneOfAnyOf;
 
@@ -578,7 +579,7 @@ private Schema processSimplifyAnyOfStringAndEnumString(Schema schema) {
             return schema;
         }
 
-        Schema s0 = null, s1 = null;
+        Schema result = null, s0 = null, s1 = null;
         if (schema.getAnyOf().size() == 2) {
             s0 = ModelUtils.unaliasSchema(openAPI, (Schema) schema.getAnyOf().get(0));
             s1 = ModelUtils.unaliasSchema(openAPI, (Schema) schema.getAnyOf().get(1));
@@ -592,15 +593,27 @@ private Schema processSimplifyAnyOfStringAndEnumString(Schema schema) {
         // find the string schema (not enum)
         if (s0 instanceof StringSchema && s1 instanceof StringSchema) {
             if (((StringSchema) s0).getEnum() != null) { // s0 is enum, s1 is string
-                return (StringSchema) s1;
+                result = (StringSchema) s1;
             } else if (((StringSchema) s1).getEnum() != null) { // s1 is enum, s0 is string
-                return (StringSchema) s0;
+                result = (StringSchema) s0;
             } else { // both are string
-                return schema;
+                result = schema;
             }
         } else {
-            return schema;
+            result = schema;
+        }
+
+        // set nullable
+        if (schema.getNullable() != null) {
+            result.setNullable(schema.getNullable());
+        }
+
+        // set default
+        if (schema.getDefault() != null) {
+            result.setDefault(schema.getDefault());
         }
+
+        return result;
     }
 
     /**
@@ -616,11 +629,22 @@ private Schema processSimplifyOneOf(Schema schema) {
         }
 
         if (schema.getOneOf() != null && !schema.getOneOf().isEmpty()) {
-            // convert null sub-schema to `nullable: true`
             for (int i = 0; i < schema.getOneOf().size(); i++) {
+                // convert null sub-schema to `nullable: true`
                 if (schema.getOneOf().get(i) == null || ((Schema) schema.getOneOf().get(i)).getType() == null) {
                     schema.getOneOf().remove(i);
                     schema.setNullable(true);
+                    continue;
+                }
+
+                // convert enum of null only to `nullable:true`
+                Schema oneOfElement = ModelUtils.getReferencedSchema(openAPI, (Schema) schema.getOneOf().get(i));
+                if (oneOfElement.getEnum() != null && oneOfElement.getEnum().size() == 1) {
+                    if ("null".equals(String.valueOf(oneOfElement.getEnum().get(0)))) {
+                        schema.setNullable(true);
+                        schema.getOneOf().remove(i);
+                        continue;
+                    }
                 }
             }
 
@@ -649,11 +673,22 @@ private Schema processSimplifyAnyOf(Schema schema) {
         }
 
         if (schema.getAnyOf() != null && !schema.getAnyOf().isEmpty()) {
-            // convert null sub-schema to `nullable: true`
             for (int i = 0; i < schema.getAnyOf().size(); i++) {
+                // convert null sub-schema to `nullable: true`
                 if (schema.getAnyOf().get(i) == null || ((Schema) schema.getAnyOf().get(i)).getType() == null) {
                     schema.getAnyOf().remove(i);
                     schema.setNullable(true);
+                    continue;
+                }
+
+                // convert enum of null only to `nullable:true`
+                Schema anyOfElement = ModelUtils.getReferencedSchema(openAPI, (Schema) schema.getAnyOf().get(i));
+                if (anyOfElement.getEnum() != null && anyOfElement.getEnum().size() == 1) {
+                    if ("null".equals(String.valueOf(anyOfElement.getEnum().get(0)))) {
+                        schema.setNullable(true);
+                        schema.getAnyOf().remove(i);
+                        continue;
+                    }
                 }
             }
 
@@ -721,4 +756,4 @@ private void processAddUnsignedToIntegerWithInvalidMaxValue(Schema schema) {
     }
 
     // ===================== end of rules =====================
-}
+}

modules/openapi-generator/src/test/java/org/openapitools/codegen/DefaultCodegenTest.java

@@ -4342,184 +4342,4 @@ public void testInlineEnumType() {
         Assert.assertFalse(inlineEnumSchemaProperty.isPrimitiveType);
     }
 
-    @Test
-    public void testOpenAPINormalizerRefAsParentInAllOf() {
-        // to test the rule REF_AS_PARENT_IN_ALLOF
-        OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_0/allOf_extension_parent.yaml");
-
-        Schema schema = openAPI.getComponents().getSchemas().get("AnotherPerson");
-        assertNull(schema.getExtensions());
-
-        Schema schema2 = openAPI.getComponents().getSchemas().get("Person");
-        assertEquals(schema2.getExtensions().get("x-parent"), "abstract");
-
-        Map<String, String> options = new HashMap<>();
-        options.put("REF_AS_PARENT_IN_ALLOF", "true");
-        OpenAPINormalizer openAPINormalizer = new OpenAPINormalizer(openAPI, options);
-        openAPINormalizer.normalize();
-
-        Schema schema3 = openAPI.getComponents().getSchemas().get("AnotherPerson");
-        assertEquals(schema3.getExtensions().get("x-parent"), true);
-
-        Schema schema4 = openAPI.getComponents().getSchemas().get("AnotherParent");
-        assertEquals(schema4.getExtensions().get("x-parent"), true);
-
-        Schema schema5 = openAPI.getComponents().getSchemas().get("Person");
-        assertEquals(schema5.getExtensions().get("x-parent"), "abstract");
-    }
-
-    @Test
-    public void testOpenAPINormalizerEnableKeepOnlyFirstTagInOperation() {
-        OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_0/enableKeepOnlyFirstTagInOperation_test.yaml");
-
-        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getGet().getTags().size(), 2);
-        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getDelete().getTags().size(), 1);
-
-        Map<String, String> options = new HashMap<>();
-        options.put("KEEP_ONLY_FIRST_TAG_IN_OPERATION", "true");
-        OpenAPINormalizer openAPINormalizer = new OpenAPINormalizer(openAPI, options);
-        openAPINormalizer.normalize();
-
-        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getGet().getTags().size(), 1);
-        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getDelete().getTags().size(), 1);
-        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getGet().getTags().get(0), "person");
-    }
-
-    @Test
-    public void testOpenAPINormalizerRemoveAnyOfOneOfAndKeepPropertiesOnly() {
-        // to test the rule REMOVE_ANYOF_ONEOF_AND_KEEP_PROPERTIIES_ONLY
-        OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_0/removeAnyOfOneOfAndKeepPropertiesOnly_test.yaml");
-
-        Schema schema = openAPI.getComponents().getSchemas().get("Person");
-        assertEquals(schema.getAnyOf().size(), 2);
-
-        Map<String, String> options = new HashMap<>();
-        options.put("REMOVE_ANYOF_ONEOF_AND_KEEP_PROPERTIES_ONLY", "true");
-        OpenAPINormalizer openAPINormalizer = new OpenAPINormalizer(openAPI, options);
-        openAPINormalizer.normalize();
-
-        Schema schema3 = openAPI.getComponents().getSchemas().get("Person");
-        assertNull(schema.getAnyOf());
-    }
-
-    @Test
-    public void testOpenAPINormalizerSimplifyOneOfAnyOfStringAndEnumString() {
-        // to test the rule SIMPLIFY_ONEOF_ANYOF_STRING_AND_ENUM_STRING
-        OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_0/simplifyAnyOfStringAndEnumString_test.yaml");
-
-        Schema schema = openAPI.getComponents().getSchemas().get("AnyOfTest");
-        assertEquals(schema.getAnyOf().size(), 2);
-
-        Map<String, String> options = new HashMap<>();
-        options.put("SIMPLIFY_ANYOF_STRING_AND_ENUM_STRING", "true");
-        OpenAPINormalizer openAPINormalizer = new OpenAPINormalizer(openAPI, options);
-        openAPINormalizer.normalize();
-
-        Schema schema3 = openAPI.getComponents().getSchemas().get("AnyOfTest");
-        assertNull(schema3.getAnyOf());
-        assertTrue(schema3 instanceof StringSchema);
-    }
-
-    @Test
-    public void testOpenAPINormalizerSimplifyOneOfAnyOf() {
-        // to test the rule SIMPLIFY_ONEOF_ANYOF
-        OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_0/simplifyOneOfAnyOf_test.yaml");
-
-        Schema schema = openAPI.getComponents().getSchemas().get("AnyOfTest");
-        assertEquals(schema.getAnyOf().size(), 2);
-        assertNull(schema.getNullable());
-
-        Schema schema2 = openAPI.getComponents().getSchemas().get("OneOfTest");
-        assertEquals(schema2.getOneOf().size(), 2);
-        assertNull(schema2.getNullable());
-
-        Schema schema5 = openAPI.getComponents().getSchemas().get("OneOfNullableTest");
-        assertEquals(schema5.getOneOf().size(), 3);
-        assertNull(schema5.getNullable());
-
-        Map<String, String> options = new HashMap<>();
-        options.put("SIMPLIFY_ONEOF_ANYOF", "true");
-        OpenAPINormalizer openAPINormalizer = new OpenAPINormalizer(openAPI, options);
-        openAPINormalizer.normalize();
-
-        Schema schema3 = openAPI.getComponents().getSchemas().get("AnyOfTest");
-        assertNull(schema3.getAnyOf());
-        assertTrue(schema3 instanceof StringSchema);
-        assertTrue(schema3.getNullable());
-
-        Schema schema4 = openAPI.getComponents().getSchemas().get("OneOfTest");
-        assertNull(schema4.getOneOf());
-        assertTrue(schema4 instanceof IntegerSchema);
-
-        Schema schema6 = openAPI.getComponents().getSchemas().get("OneOfNullableTest");
-        assertEquals(schema6.getOneOf().size(), 2);
-        assertTrue(schema6.getNullable());
-    }
-
-    @Test
-    public void testOpenAPINormalizerSimplifyBooleanEnum() {
-        // to test the rule SIMPLIFY_BOOLEAN_ENUM
-        OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_0/simplifyBooleanEnum_test.yaml");
-
-        Schema schema = openAPI.getComponents().getSchemas().get("BooleanEnumTest");
-        assertEquals(schema.getProperties().size(), 3);
-        assertTrue(schema.getProperties().get("boolean_enum") instanceof BooleanSchema);
-        BooleanSchema bs = (BooleanSchema) schema.getProperties().get("boolean_enum");
-        assertEquals(bs.getEnum().size(), 2);
-
-        Map<String, String> options = new HashMap<>();
-        options.put("SIMPLIFY_BOOLEAN_ENUM", "true");
-        OpenAPINormalizer openAPINormalizer = new OpenAPINormalizer(openAPI, options);
-        openAPINormalizer.normalize();
-
-        Schema schema3 = openAPI.getComponents().getSchemas().get("BooleanEnumTest");
-        assertEquals(schema.getProperties().size(), 3);
-        assertTrue(schema.getProperties().get("boolean_enum") instanceof BooleanSchema);
-        BooleanSchema bs2 = (BooleanSchema) schema.getProperties().get("boolean_enum");
-        assertNull(bs2.getEnum()); //ensure the enum has been erased
-    }
-
-    @Test
-    public void testOpenAPINormalizerSetTagsInAllOperations() {
-        OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_0/enableKeepOnlyFirstTagInOperation_test.yaml");
-
-        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getGet().getTags().size(), 2);
-        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getDelete().getTags().size(), 1);
-
-        Map<String, String> options = new HashMap<>();
-        options.put("SET_TAGS_FOR_ALL_OPERATIONS", "core");
-        OpenAPINormalizer openAPINormalizer = new OpenAPINormalizer(openAPI, options);
-        openAPINormalizer.normalize();
-
-        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getGet().getTags().size(), 1);
-        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getDelete().getTags().size(), 1);
-        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getGet().getTags().get(0), "core");
-        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getDelete().getTags().get(0), "core");
-    }
-
-    @Test
-    public void testAddUnsignedToIntegerWithInvalidMaxValue() {
-        OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_0/addUnsignedToIntegerWithInvalidMaxValue_test.yaml");
-
-        Schema person = openAPI.getComponents().getSchemas().get("Person");
-        assertNull(((Schema)person.getProperties().get("integer")).getExtensions());
-        assertNull(((Schema)person.getProperties().get("int32")).getExtensions());
-        assertNull(((Schema)person.getProperties().get("int64")).getExtensions());
-        assertNull(((Schema)person.getProperties().get("integer_max")).getExtensions());
-        assertNull(((Schema)person.getProperties().get("int32_max")).getExtensions());
-        assertNull(((Schema)person.getProperties().get("int64_max")).getExtensions());
-
-        Map<String, String> options = new HashMap<>();
-        options.put("ADD_UNSIGNED_TO_INTEGER_WITH_INVALID_MAX_VALUE", "true");
-        OpenAPINormalizer openAPINormalizer = new OpenAPINormalizer(openAPI, options);
-        openAPINormalizer.normalize();
-
-        Schema person2 = openAPI.getComponents().getSchemas().get("Person");
-        assertNull(((Schema)person2.getProperties().get("integer")).getExtensions());
-        assertNull(((Schema)person2.getProperties().get("int32")).getExtensions());
-        assertNull(((Schema)person2.getProperties().get("int64")).getExtensions());
-        assertTrue((Boolean)((Schema)person2.getProperties().get("integer_max")).getExtensions().get("x-unsigned"));
-        assertTrue((Boolean)((Schema)person2.getProperties().get("int32_max")).getExtensions().get("x-unsigned"));
-        assertTrue((Boolean)((Schema)person2.getProperties().get("int64_max")).getExtensions().get("x-unsigned"));
-    }
 }