fix: do not ignore empty $refs (#212)

* fix: do not ignore empty $refs

* test: node-carbon outputs slightly different error message

Author: P0lip

src/__tests__/resolver.spec.ts

@@ -181,6 +181,43 @@ describe('resolver', () => {
       });
     });
 
+    test('should attempt to resolve whitespace-only $refs', async () => {
+      const source = {
+        empty: {
+          $ref: '',
+        },
+        whitespace: {
+          $ref: ' ',
+        },
+      };
+
+      const resolver = new Resolver({
+        resolvers: {
+          file: new FileReader(),
+        },
+      });
+      const result = await resolver.resolve(source);
+
+      expect(result.errors).toStrictEqual([
+        {
+          code: 'RESOLVE_URI',
+          message: expect.stringMatching(/^Error: ENOENT: no such file or directory, open/),
+          path: ['empty'],
+          pointerStack: [],
+          uriStack: [],
+          uri: expect.any(Object),
+        },
+        {
+          code: 'RESOLVE_URI',
+          message: "Error: ENOENT: no such file or directory, open ' '",
+          path: ['whitespace'],
+          pointerStack: [],
+          uriStack: [],
+          uri: expect.any(Object),
+        },
+      ]);
+    });
+
     test('should respect immutability rules', async () => {
       const source = {
         hello: {

src/crawler.ts

@@ -42,7 +42,7 @@ export class ResolveCrawler implements Types.ICrawler {
      *   "$ref": "#/hi"
      * }
      */
-    if (ref) {
+    if (ref !== undefined) {
       this._resolveRef({
         ref,
         val: target,
@@ -69,7 +69,7 @@ export class ResolveCrawler implements Types.ICrawler {
         parentPath.push(key);
 
         // if this value a ref, resolve and continue on to the next property
-        if (ref) {
+        if (ref !== undefined) {
           this._resolveRef({
             ref,
             val,

src/runner.ts

@@ -5,6 +5,7 @@ import produce, { original } from 'immer';
 import get = require('lodash.get');
 import set = require('lodash.set');
 import * as URI from 'urijs';
+import { ExtendedURI } from './uri';
 
 import { Cache } from './cache';
 import { ResolveCrawler } from './crawler';
@@ -319,9 +320,9 @@ export class ResolveRunner implements Types.IResolveRunner {
   public computeRef = (opts: Types.IComputeRefOpts): URI | void => {
     const refStr = this.getRef(opts.key, opts.val);
 
-    if (!refStr) return;
+    if (refStr === undefined) return;
 
-    let ref = new URI(refStr);
+    let ref: URI = new ExtendedURI(refStr);
 
     // Does ref only have a fragment
     if (refStr[0] !== '#') {

src/uri.ts

@@ -0,0 +1,11 @@
+import * as BaseURI from 'urijs';
+
+export class ExtendedURI extends BaseURI {
+  constructor(private readonly _value: string) {
+    super(_value);
+  }
+
+  public get length() {
+    return this._value.length;
+  }
+}

src/utils.ts

@@ -1,4 +1,5 @@
 import * as URI from 'urijs';
+import { ExtendedURI } from './uri';
 
 const replace = (str: string, find: string, repl: string): string => {
   // modified from http://jsperf.com/javascript-replace-all/10
@@ -33,11 +34,15 @@ export const addToJSONPointer = (pointer: string, part: string): string => {
 };
 
 /** @hidden */
-export const uriToJSONPointer = (uri: URI): string => {
+export const uriToJSONPointer = (uri: URI | ExtendedURI): string => {
+  if ('length' in uri && uri.length === 0) {
+    return '';
+  }
+
   return uri.fragment() !== '' ? `#${uri.fragment()}` : uri.href() === '' ? '#' : '';
 };
 
 /** @hidden */
-export const uriIsJSONPointer = (ref: URI): boolean => {
-  return ref.path() === '';
+export const uriIsJSONPointer = (ref: URI | ExtendedURI): boolean => {
+  return (!('length' in ref) || ref.length > 0) && ref.path() === '';
 };