Add 4th info parameter (and test cases) to resolvers

Author: Corjen Moll

src/resolver.ts

@@ -4,10 +4,10 @@ import { isFunction, Promisify, isNotNullOrUndefined } from './util';
 
 export const createResolver = (resFn, errFn) => {
   const Promise = getPromise();
-  const baseResolver = (root, args = {}, context = {}) => {
+  const baseResolver = (root, args = {}, context = {}, info = {}) => {
     // Return resolving promise with `null` if the resolver function param is not a function
     if (!isFunction(resFn)) return Promise.resolve(null);
-    return Promisify(resFn)(root, args, context).catch(e => {
+    return Promisify(resFn)(root, args, context, info).catch(e => {
       // On error, check if there is an error handler.  If not, throw the original error
       if (!isFunction(errFn)) throw e;
       // Call the error handler.
@@ -23,9 +23,9 @@ export const createResolver = (resFn, errFn) => {
   baseResolver['createResolver'] = (cResFn, cErrFn) => {
     const Promise = getPromise();
 
-    const childResFn = (root, args, context) => {
+    const childResFn = (root, args, context, info = {}) => {
       // Start with either the parent resolver function or a no-op (returns null)
-      const entry = isFunction(resFn) ? Promisify(resFn)(root, args, context) : Promise.resolve(null);
+      const entry = isFunction(resFn) ? Promisify(resFn)(root, args, context, info) : Promise.resolve(null);
       return entry.then(r => {
         // If the parent returns a value, continue
         if (isNotNullOrUndefined(r)) return r;

test/unit/resolver_spec.js

@@ -141,4 +141,49 @@ describe('(unit) dist/resolver.js', () => {
       });
     })
   });
+  describe('info parameter', () => {
+    it('info parameter should be an empty object', () => {
+      const r1 = {
+        handle: (root, args, context, info) => {
+          expect(typeof info).to.equal('object')
+          expect(Object.keys(info).length).to.equal(0)
+        },
+      };
+      const resolver = createResolver(r1.handle);
+
+      resolver(null, null, null)
+    })
+    it('should pass the info parameter', () => {
+      const r1 = {
+        handle: (root, args, context, info) => {
+          expect(typeof info).to.equal('object')
+          expect(info.info).to.equal('info')
+        },
+      };
+      const resolver = createResolver(r1.handle);
+
+      resolver(null, null, null, { info: 'info' })
+    })
+    it('should pass the info parameter on a chained resolver', () => {
+      const r1 = {
+        handle: (root, args, context, info) => {
+          expect(typeof info).to.equal('object')
+          expect(info.info).to.equal('info')
+        },
+      };
+
+      const r2 = {
+        handle: (root, args, context, info) => {
+          expect(typeof info).to.equal('object')
+          expect(info.chained).to.equal('info')
+        },
+      };
+
+      const baseResolver = createResolver(r1.handle);
+      const chainedResolver = createResolver(r2.handle)
+
+      baseResolver(null, null, null, { info: 'info' })
+      chainedResolver(null, null, null, { chained: 'info' })
+    })
+  })
 });