Merge pull request #5274 from spalger/implement/promiseFromNode

[promise] fromNode helper

src/ui/public/promises/__tests__/promises.js

@@ -0,0 +1,65 @@
+import expect from 'expect.js';
+import ngMock from 'ngMock';
+import sinon from 'auto-release-sinon';
+
+describe('Promise service', function () {
+  let Promise;
+  let $rootScope;
+
+  beforeEach(ngMock.module('kibana'));
+  beforeEach(ngMock.inject(function ($injector) {
+    Promise = $injector.get('Promise');
+    $rootScope = $injector.get('$rootScope');
+  }));
+
+  describe('Promise.fromNode', function () {
+    it('creates a callback that controls a promise', function () {
+      let callback;
+      Promise.fromNode(cb => (callback = cb)());
+      $rootScope.$apply();
+      expect(callback).to.be.a('function');
+    });
+
+    it('rejects if the callback receives an error', function () {
+      let errback = sinon.stub();
+      let err = new Error();
+      Promise.fromNode(cb => cb(err)).catch(errback);
+      $rootScope.$apply();
+
+      expect(errback.callCount).to.be(1);
+      expect(errback.getCall(0).args[0]).to.be(err);
+    });
+
+    it('resolves with the second argument', function () {
+      let thenback = sinon.stub();
+      let result = {};
+      Promise.fromNode(cb => cb(null, result)).then(thenback);
+      $rootScope.$apply();
+
+      expect(thenback.callCount).to.be(1);
+      expect(thenback.getCall(0).args[0]).to.be(result);
+    });
+
+    it('resolves with an array if multiple arguments are received', function () {
+      let thenback = sinon.stub();
+      let result1 = {};
+      let result2 = {};
+      Promise.fromNode(cb => cb(null, result1, result2)).then(thenback);
+      $rootScope.$apply();
+
+      expect(thenback.callCount).to.be(1);
+      expect(thenback.getCall(0).args[0][0]).to.be(result1);
+      expect(thenback.getCall(0).args[0][1]).to.be(result2);
+    });
+
+    it('resolves with an array if multiple undefined are received', function () {
+      let thenback = sinon.stub();
+      Promise.fromNode(cb => cb(null, undefined, undefined)).then(thenback);
+      $rootScope.$apply();
+
+      expect(thenback.callCount).to.be(1);
+      expect(thenback.getCall(0).args[0][0]).to.be(undefined);
+      expect(thenback.getCall(0).args[0][1]).to.be(undefined);
+    });
+  });
+});

src/ui/public/promises/promises.js

@@ -86,6 +86,15 @@ define(function (require) {
 
       return Promise.resolve(value);
     };
+    Promise.fromNode = function (takesCbFn) {
+      return new Promise(function (resolve, reject) {
+        takesCbFn(function (err, ...results) {
+          if (err) reject(err);
+          else if (results.length > 1) resolve(results);
+          else resolve(results[0]);
+        });
+      });
+    };
 
     return Promise;
   });