Add detection of ES Modules to spies and lots of tests

lib/sinon/spy.js

@@ -8,6 +8,7 @@ var functionToString = require("./util/core/function-to-string");
 var getPropertyDescriptor = require("./util/core/get-property-descriptor");
 var sinonMatch = require("./match");
 var deepEqual = require("./util/core/deep-equal").use(sinonMatch);
+var isEsModule = require("./util/core/is-es-module");
 var spyCall = require("./call");
 var wrapMethod = require("./util/core/wrap-method");
 var sinonFormat = require("./util/core/format");
@@ -25,12 +26,16 @@ var callId = 0;
 function spy(object, property, types) {
     var descriptor, methodDesc;
 
+    if (isEsModule(object)) {
+        throw new TypeError("ES Modules cannot be spied");
+    }
+
     if (!property && typeof object === "function") {
         return spy.create(object);
     }
 
     if (!object && !property) {
-        return spy.create(function () { });
+        return spy.create(function () {});
     }
 
     if (!types) {

test/es2015/a-function-module.mjs

@@ -0,0 +1 @@
+export default function (){ return 42; }

test/es2015/a-module-with-default.mjs

@@ -0,0 +1,3 @@
+export default {
+    anExport(){ return 42; }
+}

test/es2015/module-support-assessment-test.mjs

@@ -2,13 +2,54 @@
 import referee from "referee";
 import sinon from "../../lib/sinon";
 import * as aModule from "./a-module";
-const {assert} = referee;
-
-describe("Explicit lack of support for stubbing Modules", function() {
-    it("should give a proper error message for modules without default export", function() {
-        assert.exception(function() {
-            sinon.stub(aModule, "anExport").returns(400);
-        },
-        /TypeError: No support for stubbing ES Modules/);
+import aModuleWithDefaultExport from "./a-module-with-default";
+import functionModule, * as functionModuleAlternative from "./a-function-module";
+const {assert, refute} = referee;
+
+function createTestSuite(action){
+    var stub;
+    var errorRegEx = /TypeError: ES Modules cannot be (stubbed|spied)/;
+
+    afterEach(function() {
+        stub && stub.restore && stub.restore();
     });
-});
+
+    describe("sinon." + action + "()", function(){
+        describe("Modules with objects as their default export", function() {
+    afterEach(function() {
+        stub && stub.restore && stub.restore();
+    });
+            it("should NOT result in error", function() {
+                refute.exception(function() {
+                    stub = sinon[action](aModuleWithDefaultExport, "anExport");
+                });
+            });
+
+            it("should spy/stub an exported function", function() {
+                stub = sinon[action](aModuleWithDefaultExport, "anExport");
+                aModuleWithDefaultExport.anExport();
+                aModuleWithDefaultExport.anExport();
+                assert(stub.callCount === 2);
+            });
+        });
+
+        describe("Modules without default export", function() {
+            it("should give a proper error message", function() {
+                assert.exception(function() {
+                    sinon[action](aModule, "anExport");
+                }, errorRegEx);
+            });
+        });
+
+        describe("Modules that exports a function as their default export", function() {
+            it("should not be possible to spy/stub the default export using a wrapper for the exports", function() {
+                assert.exception(function() {
+                    stub = sinon[action](functionModuleAlternative, "anExport");
+                }, errorRegEx);
+            });
+        });
+    });
+}
+
+createTestSuite('stub');
+createTestSuite('spy');