test: add nullable-oneof.yaml and unit test for simplifyNullableOneOf (fix #32520)

Author: sshekhar563

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

@@ -1253,56 +1253,23 @@ public void testRemoveXInternalFromInlineProperties() {
 
     @Test
     public void testSimplifyNullableOneOf() {
-         // 1. Define the OpenAPI spec string that contains the bug pattern
-         final String yaml =
-                "openapi: 3.0.0\n" +
-                "info:\n" +
-                "  version: 1.0.0\n" +
-                "  title: API\n" +
-                "paths:\n" +
-                "  /test:\n" +
-                "    get:\n" +
-                "      responses:\n" +
-                "        '200':\n" +
-                "          description: OK\n" +
-                "          content:\n" +
-                "            application/json:\n" +
-                "              schema:\n" +
-                "                $ref: '#/components/schemas/Recipe'\n" +
-                "components:\n" +
-                "  schemas:\n" +
-                "    Category:\n" +
-                "      type: object\n" +
-                "      properties:\n" +
-                "        name:\n" +
-                "          type: string\n" +
-                "    Recipe:\n" +
-                "      type: object\n" +
-                "      properties:\n" +
-                "        category:\n" + // This is the property with the nullable oneOf
-                "          description: 'This should become nullable'\n" +
-                "          oneOf:\n" +
-                "            - $ref: '#/components/schemas/Category'\n" +
-                "            - type: 'null'\n";
-
-         // 2. Load the spec and run the normalizer (with default rules)
-          final OpenAPI openAPI = TestUtils.parseSpec(yaml);
+         // Load from YAML file for consistency
+         final OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_0/nullable-oneof.yaml");
+         // Run the normalizer
          new OpenAPINormalizer(openAPI, Collections.emptyMap()).normalize();
-
-         // 3. Get the specific schema property that should have been fixed
+         
+         // Case 1: Recipe -> ref + null
          Schema recipeSchema = openAPI.getComponents().getSchemas().get("Recipe");
          Schema categoryProperty = (Schema) recipeSchema.getProperties().get("category");
-
-         // 4. Assert that the fix worked as expected
-         assertNotNull(categoryProperty, "The category property should not be null.");
-        
-         // Key Assertions:
-         assertTrue(categoryProperty.getNullable(), "The property should be marked as nullable.");
-         assertNull(categoryProperty.getOneOf(), "The oneOf should have been removed.");
-         assertEquals(categoryProperty.get$ref(), "#/components/schemas/Category", "The $ref should be preserved.");
-        
-         // Also check that metadata was preserved
-         assertEquals(categoryProperty.getDescription(), "This should become nullable'");
+         assertNotNull(categoryProperty);
+         assertTrue(categoryProperty.getNullable());
+         assertNull(categoryProperty.getOneOf());
+         assertEquals(categoryProperty.get$ref(), "#/components/schemas/Category");
+
+         // Case 2: Inline object + null
+         Schema inline = openAPI.getComponents().getSchemas().get("CategoryInline");
+         assertTrue(inline.getNullable());
+         assertNull(inline.getOneOf());
     }
 
     public static class RemoveRequiredNormalizer extends OpenAPINormalizer {

modules/openapi-generator/src/test/resources/3_0/nullable-oneof.yaml

@@ -0,0 +1,39 @@
+openapi: 3.0.0
+info:
+  version: 1.0.0
+  title: API
+paths:
+  /test:
+    get:
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Recipe'
+
+components:
+  schemas:
+    Category:
+      type: object
+      properties:
+        name:
+          type: string
+
+    Recipe:
+      type: object
+      properties:
+        category:
+          description: This should become nullable
+          oneOf:
+            - $ref: '#/components/schemas/Category'
+            - type: 'null'
+
+    CategoryInline:
+      oneOf:
+        - type: object
+          properties:
+            type:
+              type: string
+        - type: 'null'