feat: support mock prop with getter setter (#4)

* feat: support mock prop with getter setter

* feat: add logic check

* feat: add unittest

* unittest: add throw error case

* feat: typo

* feat: refactor && add setter unittest case

* feat: code format

* feat: without set the default value

* feat: add getter/setter example

* feat: update readme

* Update readme with shorter example

* More succinct

Author: perzy

README.md

@@ -19,13 +19,28 @@ muk(fs, 'readFile', (path, callback) => {
 });
 ```
 
+Object props mocking with setter/getter.
+
+```js
+const muk = require('muk-prop');
+
+const obj = { _a: 1 };
+muk(obj, 'a', {
+  set: function(val) { this._a = val * 2; },
+  get: function(val) { return this._a; },
+});
+
+obj.a = 2;
+console.log(obj.a); // 4
+```
+
 Check if member has been mocked.
 
 ```js
 muk.isMocked(fs, 'readFile'); // true
 ```
 
-Restore all mocked methods after tests.
+Restore all mocked methods/props after tests.
 
 ```js
 muk.restore();

lib/index.js

@@ -6,14 +6,13 @@ var cache = new Map();
 
 
 /**
- * Mocks a method of an object.
+ * Mocks a value of an object.
  *
  * @param {Object} obj
  * @param {string} key
- * @param {!Function} method
+ * @param {!Function|Object} value
  */
-var method = module.exports = (obj, key, method) => {
-  method = method === undefined ? () => {} : method;
+var method = module.exports = (obj, key, value) => {
   var hasOwnProperty = obj.hasOwnProperty(key);
   mocks.push({
     obj,
@@ -36,13 +35,22 @@ var method = module.exports = (obj, key, method) => {
   }
   flag.add(key);
 
-  Object.defineProperty(obj, key, {
-    writable: true,
+  var descriptor = {
     configurable: true,
     enumerable: true,
-    value: method
-  });
+  };
+  
+  if (value && (value.get || value.set)) {
+    // Default to undefined
+    descriptor.get = value.get;
+    descriptor.set = value.set;
+  } else {
+    // Without getter/setter mode
+    descriptor.value = value;
+    descriptor.writable = true;
+  }
 
+  Object.defineProperty(obj, key, descriptor);
 };
 
 /**

test/method-test.js

@@ -115,10 +115,9 @@ describe('Mock property', () => {
     assert(!hasOwnProperty(process.env, 'notExistProp'), 'notExistProp is deleted');
   });
 
-  it('should mock function when method is null', () => {
+  it('should be undefined when value is not set', () => {
     muk(config, 'enableCache');
-    assert.equal(typeof config.enableCache, 'function', 'enableCache is function');
-    assert.equal(config.enableCache(), undefined, 'enableCache return undefined');
+    assert.equal(config.enableCache, undefined, 'enableCache is undefined');
   });
 
   it('should mock property on prototype', () => {
@@ -167,6 +166,101 @@ describe('Mock getter', () => {
   });
 });
 
+describe('Mock value with getter', () => {
+  var obj = {
+    a: 1,
+  };
+
+  afterEach(muk.restore);
+  
+  it('Value are new getter after mocked', () => {
+    muk(obj, 'a', {
+      get: () => 2,
+    });
+    assert.equal(obj.a, 2, 'property a of obj is 2 with getter');
+  });
+  
+  it('Should throw error when getter', () => {
+    muk(obj, 'a', {
+      get: () => {
+        throw new Error('oh no');
+      }
+    });
+
+    try {
+      obj.a;
+    } catch (e) {
+      assert.equal(e.message, 'oh no')
+    }
+  });
+  
+  it('Should have original getter after muk.restore()', () => {
+    muk(obj, 'a', {
+      get: () => 2,
+    });
+    
+    muk.restore();
+    assert.equal(obj.a, 1, 'property a of obj is equal to original');
+  });
+});
+
+describe('Mock value with setter', () => {
+  var obj = {
+    _a: 1,
+  };
+
+  Object.defineProperty(obj, 'a', {
+    configurable: true,
+    set: function(value) {
+      this._a = value;
+    },
+    get: function() {
+      return this._a;
+    },
+  })
+
+  afterEach(muk.restore);
+  
+  it('Value are new setter after mocked', () => {
+    muk(obj, 'a', {
+      set: function(value) {
+        this._a = value + 1;
+      },
+      get: function() {
+        return this._a;
+      },
+    });
+    obj.a = 2;
+    assert.equal(obj.a, 3, 'property a of obj is 3 with getter');
+  });
+  
+  it('Should throw error when setter', () => {
+    muk(obj, 'a', {
+      set: () => {
+        throw new Error('oh no');
+      }
+    });
+
+    try {
+      obj.a = 2;
+    } catch (e) {
+      assert.equal(e.message, 'oh no')
+    }
+  });
+  
+  it('Should have original setter after muk.restore()', () => {
+    muk(obj, 'a', {
+      set: function(value) {
+        this._a = value + 1;
+      },
+    });
+    
+    muk.restore();
+    obj.a = 2;
+    assert.equal(obj.a, 2, 'property a of obj is equal to original');
+  });
+});
+
 describe('Mock check', () => {
 
   afterEach(muk.restore);