Fix issue #1919 by adding a new util function to prevent duplicate co…

…de (#1942)

* Issue #1919 Refactor to reduce duplicate code and add tests

* undo changes to package-lock.json

lib/sinon/behavior.js

@@ -5,9 +5,9 @@ var extend = require("./util/core/extend");
 var functionName = require("@sinonjs/commons").functionName;
 var nextTick = require("./util/core/next-tick");
 var valueToString = require("@sinonjs/commons").valueToString;
+var exportAsyncBehaviors = require("./util/core/export-async-behaviors");
 
 var concat = arrayProto.concat;
-var forEach = arrayProto.forEach;
 var join = arrayProto.join;
 var reverse = arrayProto.reverse;
 var slice = arrayProto.slice;
@@ -205,22 +205,6 @@ var proto = {
     }
 };
 
-function createAsyncVersion(syncFnName) {
-    return function() {
-        var result = this[syncFnName].apply(this, arguments);
-        this.callbackAsync = true;
-        return result;
-    };
-}
-
-// create asynchronous versions of callsArg* and yields* methods
-forEach(Object.keys(proto), function(method) {
-    // need to avoid creating anotherasync versions of the newly added async methods
-    if (method.match(/^(callsArg|yields)/) && !method.match(/Async/)) {
-        proto[method + "Async"] = createAsyncVersion(method);
-    }
-});
-
 function createBehavior(behaviorMethod) {
     return function() {
         this.defaultBehavior = this.defaultBehavior || proto.create(this);
@@ -240,4 +224,7 @@ function addBehavior(stub, name, fn) {
 
 proto.addBehavior = addBehavior;
 proto.createBehavior = createBehavior;
-module.exports = proto;
+
+var asyncBehaviors = exportAsyncBehaviors(proto);
+
+module.exports = extend({}, proto, asyncBehaviors);

lib/sinon/default-behaviors.js

@@ -2,8 +2,9 @@
 
 var arrayProto = require("@sinonjs/commons").prototypes.array;
 var isPropertyConfigurable = require("./util/core/is-property-configurable");
+var exportAsyncBehaviors = require("./util/core/export-async-behaviors");
+var extend = require("./util/core/extend");
 
-var forEach = arrayProto.forEach;
 var slice = arrayProto.slice;
 
 var useLeftMostCallback = -1;
@@ -27,7 +28,7 @@ function throwsException(fake, error, message) {
     }
 }
 
-module.exports = {
+var defaultBehaviors = {
     callsFake: function callsFake(fake, fn) {
         fake.fakeFn = fn;
     },
@@ -260,18 +261,6 @@ module.exports = {
     }
 };
 
-function createAsyncVersion(syncFnName) {
-    return function() {
-        var result = module.exports[syncFnName].apply(this, arguments);
-        this.callbackAsync = true;
-        return result;
-    };
-}
+var asyncBehaviors = exportAsyncBehaviors(defaultBehaviors);
 
-// create asynchronous versions of callsArg* and yields* methods
-forEach(Object.keys(module.exports), function(method) {
-    // need to avoid creating anotherasync versions of the newly added async methods
-    if (method.match(/^(callsArg|yields)/) && !method.match(/Async/)) {
-        module.exports[method + "Async"] = createAsyncVersion(method);
-    }
-});
+module.exports = extend({}, defaultBehaviors, asyncBehaviors);

lib/sinon/util/core/export-async-behaviors.js

@@ -0,0 +1,22 @@
+"use strict";
+
+var arrayProto = require("@sinonjs/commons").prototypes.array;
+var reduce = arrayProto.reduce;
+
+module.exports = function exportAsyncBehaviors(behaviorMethods) {
+    return reduce(
+        Object.keys(behaviorMethods),
+        function(acc, method) {
+            // need to avoid creating another async versions of the newly added async methods
+            if (method.match(/^(callsArg|yields)/) && !method.match(/Async/)) {
+                acc[method + "Async"] = function() {
+                    var result = behaviorMethods[method].apply(this, arguments);
+                    this.callbackAsync = true;
+                    return result;
+                };
+            }
+            return acc;
+        },
+        {}
+    );
+};

test/util/core/export-async-behaviors-test.js

@@ -0,0 +1,35 @@
+"use strict";
+
+var referee = require("@sinonjs/referee");
+var assert = referee.assert;
+var exportAsyncBehaviors = require("../../../lib/sinon/util/core/export-async-behaviors");
+
+describe("util/core/exportAsyncBehaviors", function() {
+    describe("for methods with names starting with 'callsArg' or 'yields'", function() {
+        it("should create an async version", function() {
+            var methods = {
+                yieldsOn: function yieldsOn() {
+                    return "2";
+                },
+                callsArg: function callsArg() {
+                    return "3";
+                }
+            };
+            assert.equals(Object.keys(exportAsyncBehaviors(methods)), ["yieldsOnAsync", "callsArgAsync"]);
+        });
+    });
+
+    describe("for methods with names not starting with 'callsArg' or 'yields'", function() {
+        it("should not add any new methods", function() {
+            var methods = {
+                callsFake: function callsFake() {
+                    return "1";
+                },
+                resolvesThisAsync: function resolvesThisAsync() {
+                    return "4";
+                }
+            };
+            assert.equals(Object.keys(exportAsyncBehaviors(methods)), []);
+        });
+    });
+});