fixes issue #1368 by adding stub#resolvesThis

lib/sinon/behavior.js

@@ -117,6 +117,7 @@ var proto = {
                 this.exception ||
                 typeof this.returnArgAt === "number" ||
                 this.returnThis ||
+                this.resolveThis ||
                 typeof this.throwArgAt === "number" ||
                 this.fakeFn ||
                 this.returnValueDefined);
@@ -142,6 +143,8 @@ var proto = {
             throw args[this.throwArgAt];
         } else if (this.fakeFn) {
             return this.fakeFn.apply(context, args);
+        } else if (this.resolveThis) {
+            return (this.promiseLibrary || Promise).resolve(context);
         } else if (this.resolve) {
             return (this.promiseLibrary || Promise).resolve(this.returnValue);
         } else if (this.reject) {

lib/sinon/default-behaviors.js

@@ -155,6 +155,7 @@ module.exports = {
     resolves: function resolves(fake, value) {
         fake.returnValue = value;
         fake.resolve = true;
+        fake.resolveThis = false;
         fake.reject = false;
         fake.returnValueDefined = true;
         fake.exception = undefined;
@@ -173,6 +174,7 @@ module.exports = {
         }
         fake.returnValue = reason;
         fake.resolve = false;
+        fake.resolveThis = false;
         fake.reject = true;
         fake.returnValueDefined = true;
         fake.exception = undefined;
@@ -181,6 +183,16 @@ module.exports = {
         return fake;
     },
 
+    resolvesThis: function resolvesThis(fake) {
+        fake.returnValue = undefined;
+        fake.resolve = false;
+        fake.resolveThis = true;
+        fake.reject = false;
+        fake.returnValueDefined = false;
+        fake.exception = undefined;
+        fake.fakeFn = undefined;
+    },
+
     callThrough: function callThrough(fake) {
         fake.callsThrough = true;
     },

lib/sinon/stub.js

@@ -123,6 +123,7 @@ var proto = {
         delete this.throwArgAt;
         delete this.fakeFn;
         this.returnThis = false;
+        this.resolveThis = false;
 
         fakes.forEach(function (fake) {
             fake.resetBehavior();

test/stub-test.js

@@ -285,6 +285,50 @@ describe("stub", function () {
         });
     });
 
+    describe(".resolvesThis", function () {
+        afterEach(function () {
+            if (Promise.resolve.restore) {
+                Promise.resolve.restore();
+            }
+        });
+
+        it("returns a promise resolved with this", function () {
+            var instance = {};
+            instance.stub = createStub.create();
+            instance.stub.resolvesThis();
+
+            return instance.stub().then(function (actual) {
+                assert.same(actual, instance);
+            });
+        });
+
+        it("returns a promise resolved with the context bound with stub#call", function () {
+            var stub = createStub.create();
+            stub.resolvesThis();
+            var object = {};
+
+            return stub.call(object).then(function (actual) {
+                assert.same(actual, object);
+            });
+        });
+
+        it("returns a promise resolved with the context bound with stub#apply", function () {
+            var stub = createStub.create();
+            stub.resolvesThis();
+            var object = {};
+
+            return stub.apply(object).then(function (actual) {
+                assert.same(actual, object);
+            });
+        });
+
+        it("returns the stub itself, allowing to chain function calls", function () {
+            var stub = createStub.create();
+
+            assert.same(stub.resolvesThis(), stub);
+        });
+    });
+
     describe(".returnsArg", function () {
         it("returns argument at specified index", function () {
             var stub = createStub.create();
@@ -2171,6 +2215,16 @@ describe("stub", function () {
             refute.defined(instance.stub());
         });
 
+        it("cleans 'resolvesThis' behavior, so the stub does not resolve nor returns anything", function () {
+            var instance = {};
+            instance.stub = createStub.create();
+            instance.stub.resolvesThis();
+
+            instance.stub.resetBehavior();
+
+            refute.defined(instance.stub());
+        });
+
         describe("does not touch properties that are reset by 'reset'", function () {
             it(".calledOnce", function () {
                 var stub = createStub();