Allow replacing a service by a mocked one.

Author: armandabric

package.json

@@ -12,11 +12,11 @@
   ],
   "main": "index.js",
   "scripts": {
-    "bdd": "mocha --colors --reporter=dot --watch --recursive tests",
-    "coverage": "istanbul cover node_modules/.bin/_mocha --report lcovonly -- --reporter=dot --recursive tests",
-    "coverage-upload": "cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js",
+    "bdd": "NODE_ENV=test mocha --colors --reporter=dot --watch --recursive tests",
+    "coverage": "NODE_ENV=test istanbul cover node_modules/.bin/_mocha --report lcovonly -- --reporter=dot --recursive tests",
+    "coverage-upload": "NODE_ENV=test cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js",
     "lint": "eslint --color .",
-    "test": "mocha --colors --reporter=dot --recursive tests"
+    "test": "NODE_ENV=test mocha --colors --reporter=dot --recursive tests"
   },
   "repository": {
     "type": "git",

src/Container.js

@@ -18,6 +18,8 @@ var Container = function Container(serviceDefinitionCollection, parameterCollect
 };
 
 /**
+ * Return a parameter value.
+ *
  * @param {String} name
  * @return {*|null}
  */
@@ -32,6 +34,8 @@ Container.prototype.getParameter = function (name) {
 };
 
 /**
+ * Return a sercice instance.
+ *
  * @param {String} name
  * @return {*}
  */
@@ -53,4 +57,24 @@ Container.prototype.getService = function (name) {
     return serviceInstance;
 };
 
+if (process.env.NODE_ENV === 'test') {
+    /**
+     * Replace a service instance by a mocked instance. Only avialable in test environement.
+     *
+     * @param {String} name
+     * @param {Function} mock
+     */
+    Container.prototype.mockService = function (name, mock) {
+        if (!this.serviceDefinitionCollection.hasServiceDefinition(name)) {
+            throw new Error('Unknown service "' + name + '".');
+        }
+
+        if (!this.serviceStorage.hasInstance(name)) {
+            this.serviceStorage.addInstance(name, mock);
+            return;
+        }
+
+        this.serviceStorage.replaceInstance(name, mock);
+    };
+}
 module.exports = Container;

src/ServiceStorage.js

@@ -27,6 +27,18 @@ ServiceStorage.prototype.addInstance = function (name, instance) {
     this.instances[name] = instance;
 };
 
+/**
+ * @param {String} name
+ * @param {*} instance
+ */
+ServiceStorage.prototype.replaceInstance = function (name, instance) {
+    if (!this.hasInstance(name)) {
+        throw new Error('There is no service to replace with name the "' + name + '".');
+    }
+
+    this.instances[name] = instance;
+};
+
 /**
  * @param {String} name
  * @return {*}

tests/functionals/ContainerFactorySpec.js

@@ -8,6 +8,12 @@ var servicesConfigurationErroredWithUnknownDependencies = require('./../fixture/
 var ServiceA = require('./../fixture/valid/ServiceA');
 
 describe('ContainerFactory', function () {
+    var previousProcessEnv = process.env.NODE_ENV;
+
+    afterEach(function () {
+        process.env.NODE_ENV = previousProcessEnv;
+    });
+
     it('should return the parameter value', function () {
         var container = ContainerFactory.create(servicesConfigurationValid.services, servicesConfigurationValid.parameters);
 

tests/functionals/ContainerSpec.js

@@ -1,6 +1,7 @@
 'use strict';
 
 var expect = require('chai').expect;
+var sinon = require('sinon');
 var Container = require('./../../src/Container');
 var Parameter = require('./../../src/Parameter');
 var ParameterCollection = require('./../../src/ParameterCollection');
@@ -137,4 +138,23 @@ describe('Container', function () {
         expect(serviceC.bar).to.be.equal(42);
         expect(serviceC.serviceA).to.be.equal(serviceA);
     });
+
+    it('should replace a service by a mocked one', function () {
+        var serviceDefinitionCollection = sinon.createStubInstance(ServiceDefinitionCollection);
+        serviceDefinitionCollection.hasServiceDefinition.withArgs('foo').returns(true);
+
+        var parameterCollection = sinon.createStubInstance(ParameterCollection);
+
+        var fakeServiceMock = sinon.spy();
+
+        var container = new Container(serviceDefinitionCollection, parameterCollection);
+        container.mockService('foo', fakeServiceMock);
+
+        expect(container.getService('foo')).to.be.equals(fakeServiceMock);
+        expect(fakeServiceMock).to.not.have.been.called;
+    });
+
+    it.skip('should replace a cached service by a mocker one', function () {
+        // TODO
+    });
 });

tests/units/ContainerSpec.js

@@ -0,0 +1,58 @@
+'use strict';
+
+var expect = require('chai').expect;
+var sinon = require('sinon');
+var Container = require('./../../src/Container');
+var ServiceDefinitionCollection = require('./../../src/ServiceDefinitionCollection');
+var ParameterCollection = require('./../../src/ParameterCollection');
+
+describe('Container', function () {
+    var previousProcessEnv = process.env.NODE_ENV;
+
+    afterEach(function () {
+        process.env.NODE_ENV = previousProcessEnv;
+    });
+
+    /**
+     * @see http://stackoverflow.com/a/16060619
+     * @param {[type]} module
+     * @return {[type]}
+     */
+    function requireUncached(module) {
+        delete require.cache[require.resolve(module)]
+        return require(module)
+    }
+
+    it('should throw a error when trying to mock an undefined service', function () {
+        var serviceDefinitionCollection = sinon.createStubInstance(ServiceDefinitionCollection);
+        var parameterCollection = sinon.createStubInstance(ParameterCollection);
+
+        var container = new Container(serviceDefinitionCollection, parameterCollection);
+
+        expect(function () {
+            container.mockService('foo', function () {});
+        }).to.throw('Unknown service "foo".');
+    });
+
+    it('should provide an api to mock a service in test environement', function () {
+        var serviceDefinitionCollection = sinon.createStubInstance(ServiceDefinitionCollection);
+        var parameterCollection = sinon.createStubInstance(ParameterCollection);
+
+        process.env.NODE_ENV = 'test';
+        var FreshContainer = requireUncached('./../../src/Container');
+
+        var container = new FreshContainer(serviceDefinitionCollection, parameterCollection);
+        expect(container).to.have.property('mockService');
+    });
+
+    it('should not provide an api to mock a service in production environement', function () {
+        var serviceDefinitionCollection = sinon.createStubInstance(ServiceDefinitionCollection);
+        var parameterCollection = sinon.createStubInstance(ParameterCollection);
+
+        process.env.NODE_ENV = 'production';
+        var FreshContainer = requireUncached('./../../src/Container');
+
+        var container = new FreshContainer(serviceDefinitionCollection, parameterCollection);
+        expect(container).to.not.have.property('mockService');
+    });
+});

tests/units/ServiceStorageSpec.js

@@ -4,7 +4,7 @@ var expect = require('chai').expect;
 var ServiceStorage = require('./../../src/ServiceStorage');
 
 describe('ServiceStorage', function () {
-    it('should  add an instance to the storage and return it', function () {
+    it('should add an instance to the storage and return it', function () {
         var serviceStorage = new ServiceStorage();
 
         var someInstance = Object.create({a: 'bar'});
@@ -43,4 +43,26 @@ describe('ServiceStorage', function () {
         expect(serviceStorage.hasInstance('foo')).to.be.true;
         expect(serviceStorage.hasInstance('bar')).to.be.false;
     });
+
+    it('should replace an instance to the storage and return it', function () {
+        var serviceStorage = new ServiceStorage();
+
+        var someInstance = Object.create({a: 'bar'});
+        var someOthenInstance = Object.create({b: 'baz'});
+
+        serviceStorage.addInstance('foo', someInstance);
+        serviceStorage.replaceInstance('foo', someOthenInstance);
+
+        expect(serviceStorage.getInstance('foo')).to.equals(someOthenInstance);
+    });
+
+    it('should throw an exception if there is no instance to replace', function () {
+        var serviceStorage = new ServiceStorage();
+
+        var someInstance = Object.create({a: 'bar'});
+
+        expect(function () {
+            serviceStorage.replaceInstance('foo', someInstance);
+        }).to.throw('There is no service to replace with name the "foo".');
+    });
 });

tests/world.js

@@ -4,3 +4,7 @@ var chai = require("chai");
 var sinonChai = require("sinon-chai");
 
 chai.use(sinonChai);
+
+if (process.env.NODE_ENV !== 'test') {
+    console.warn('Warning: you\'re not running the tests in test environment. Define the NODE_ENV variable to "test".');
+}