fix: handle direct circular file $refs (#219)

src/__tests__/fixtures/schemas/circular-file-reference.json

@@ -0,0 +1,10 @@
+{
+  "anyOf": [
+    {
+      "$ref": "circular-file-reference.json"
+    },
+    {
+      "$ref": "circular-file-reference.json#/anyOf"
+    }
+  ]
+}

src/__tests__/resolver.spec.ts

@@ -1208,6 +1208,37 @@ describe('resolver', () => {
         ],
       });
     });
+
+    test('should handle circular direct file reference', async () => {
+      const resolver = new Resolver({
+        resolvers: {
+          file: new FileReader(),
+        },
+      });
+      const docUri = join(__dirname, './fixtures/schemas/circular-file-reference.json');
+      const resolved = await resolver.resolve(JSON.parse(fs.readFileSync(docUri, 'utf8')), {
+        baseUri: docUri,
+      });
+
+      expect(resolved.errors).toEqual([]);
+      expect(resolved.result).toStrictEqual({
+        anyOf: [
+          {
+            anyOf: [
+              {
+                $ref: 'circular-file-reference.json',
+              },
+              {
+                $ref: 'circular-file-reference.json#/anyOf',
+              },
+            ],
+          },
+          {
+            $ref: 'circular-file-reference.json#/anyOf',
+          },
+        ],
+      });
+    });
   });
 
   describe('cache', () => {

src/runner.ts

@@ -349,6 +349,10 @@ export class ResolveRunner implements Types.IResolveRunner {
       }
     }
 
+    if (String(ref).length > 0 && this.isFile(this.baseUri) && this.isFile(ref) && this.baseUri.path() === ref.path()) {
+      ref = new ExtendedURI(`#${ref.fragment()}`);
+    }
+
     if (this.transformRef) {
       return this.transformRef(
         {