fix: add nullable to null test

Author: b41ex

test/helper/resources/3_0-to-3_1/nullable-to-union/after.yaml

@@ -0,0 +1,16 @@
+openapi: 3.1.0
+info:
+  title: test
+  version: 0.1.0
+paths:
+  /path1:
+    get:
+      responses:
+        '200':
+          description: OK
+          content:
+            'application/json':
+              schema:
+                anyOf:
+                  - type: string
+                  - type: 'null'

test/helper/resources/3_0-to-3_1/nullable-to-union/before.yaml

@@ -0,0 +1,15 @@
+openapi: 3.0.3
+info:
+  title: test
+  version: 0.1.0
+paths:
+  /path1:
+    get:
+      responses:
+        '200':
+          description: OK
+          content:
+            'application/json':
+              schema:
+                type: string
+                nullable: true

test/oas-3_0-to-3_1.test.ts

@@ -42,4 +42,25 @@ describe('OpenAPI 3.0 to 3.1 Migration Tests', () => {
       }),
     ]))
   })
+
+  test.skip('nullable-to-union', () => {
+    // Load the before and after files
+    const beforePath = './test/helper/resources/3_0-to-3_1/nullable-to-union/before.yaml'
+    const afterPath = './test/helper/resources/3_0-to-3_1/nullable-to-union/after.yaml'
+    
+    const beforeSource = load(readFileSync(beforePath).toString())
+    const afterSource = load(readFileSync(afterPath).toString())
+    
+    // Call apiDiff
+    const { diffs } = apiDiff(beforeSource, afterSource, {
+      ...TEST_NORMALIZE_OPTIONS,
+      beforeSource,
+      afterSource,
+    })
+    
+    // Check the result - expecting changes from nullable: true to union types
+    expect(diffs).toEqual(diffsMatcher([
+      // TODO: Add assertions for nullable to union type changes
+    ]))
+  })
 })