Add more details on missing $ref (#368)

* add more details on missing $ref

* Fix lint errors

Author: AlexHolly

lib/pointer.ts

@@ -88,6 +88,7 @@ class Pointer<S extends object = JSONSchema, O extends ParserOptions<S> = Parser
    */
   resolve(obj: S, options?: O, pathFromRoot?: string) {
     const tokens = Pointer.parse(this.path, this.originalPath);
+    const found: any = [];
 
     // Crawl the object, one token at a time
     this.value = unwrapOrThrow(obj);
@@ -103,6 +104,7 @@ class Pointer<S extends object = JSONSchema, O extends ParserOptions<S> = Parser
       }
 
       const token = tokens[i];
+      
       if (this.value[token] === undefined || (this.value[token] === null && i === tokens.length - 1)) {
         // one final case is if the entry itself includes slashes, and was parsed out as a token - we can join the remaining tokens and try again
         let didFindSubstringSlashMatch = false;
@@ -120,10 +122,23 @@ class Pointer<S extends object = JSONSchema, O extends ParserOptions<S> = Parser
         }
 
         this.value = null;
-        throw new MissingPointerError(token, decodeURI(this.originalPath));
+
+        let path: any = '';
+
+        if (path !== undefined) {
+          path = this.$ref.path;
+        }
+
+        const targetRef = this.path.replace(path, '');
+        const targetFound = Pointer.join('', found);
+        const parentPath = pathFromRoot?.replace(path, '');
+        
+        throw new MissingPointerError(token, decodeURI(this.originalPath), targetRef, targetFound, parentPath);
       } else {
         this.value = this.value[token];
       }
+
+      found.push(token)
     }
 
     // Resolve the final value

lib/util/errors.ts

@@ -123,8 +123,17 @@ export class UnmatchedResolverError extends JSONParserError {
 export class MissingPointerError extends JSONParserError {
   code = "EMISSINGPOINTER" as JSONParserErrorType;
   name = "MissingPointerError";
-  constructor(token: string, path: string) {
+  public targetToken: any;
+  public targetRef: string;
+  public targetFound: string;
+  public parentPath: string; 
+  constructor(token: any, path: any, targetRef: any, targetFound: any, parentPath: any) {
     super(`Missing $ref pointer "${getHash(path)}". Token "${token}" does not exist.`, stripHash(path));
+
+    this.targetToken = token;
+    this.targetRef = targetRef;
+    this.targetFound = targetFound;
+    this.parentPath = parentPath;
   }
 }
 

test/specs/missing-pointers/error-details.yaml

@@ -0,0 +1,16 @@
+paths:
+  /pet:
+    post:
+      tags:
+        - pet
+      parameters:
+        - $ref: '#/components/parameters/ThisIsMissing'
+components:
+  parameters:
+    petId:
+      name: petId
+      in: path
+      required: true
+      schema:
+        type: integer
+        format: int64

test/specs/missing-pointers/missing-pointers.spec.ts

@@ -90,5 +90,28 @@ describe("Schema with missing pointers", () => {
         ]);
       }
     });
+
+    it("should throw an missing pointer error with details for target and parent", async () => {
+      const parser = new $RefParser();
+      try {
+        await parser.dereference({ foo: { $ref: path.abs("test/specs/missing-pointers/error-details.yaml") }}, { continueOnError: true });
+        helper.shouldNotGetCalled();
+      }
+      catch (err) {
+        expect(err).to.be.instanceof(JSONParserErrorGroup);
+        expect(err.files).to.equal(parser);
+        expect(err.message).to.have.string("1 error occurred while reading '");
+        expect(err.errors).to.containSubset([
+          {
+            name: MissingPointerError.name,
+            message: 'Missing $ref pointer \"#/components/parameters/ThisIsMissing\". Token \"ThisIsMissing\" does not exist.',
+            targetToken: 'ThisIsMissing',
+            targetRef: "#/components/parameters/ThisIsMissing",
+            targetFound: "#/components/parameters",
+            parentPath: "#/paths/~1pet/post/parameters/0"
+          }
+        ]);
+      }
+    });
   });
 });