Merge pull request #51 from tlvince/remcohaszing-no-assign-spyon

feat(no-assign-spyon): add no-assign-spyon rule

.vimrc

@@ -1,2 +1,2 @@
 let $PATH = './node_modules/.bin:' . $PATH
-let g:syntastic_javascript_checkers = ['eslint']
+let g:neomake_javascript_enabled_makers = ['standard']

README.md

@@ -46,13 +46,15 @@ configuration files.
 
 Rule                         | Recommended      | Options
 ----                         | -----------      | -------
+[named-spy][]                | 0                |
 [no-focused-tests][]         | 2                |
 [no-disabled-tests][]        | 1                |
-[no-spec-dupes][]            | 1, `'block'`     | `['block', 'branch']`
 [no-suite-dupes][]           | 1, `'block'`     | `['block', 'branch']`
-[no-suite-callback-args][]   | 2                |
+[no-spec-dupes][]            | 1, `'block'`     | `['block', 'branch']`
 [missing-expect][]           | 0, `'expect()'`  | expectation function names
+[no-suite-callback-args][]   | 2                |
 [valid-expect][]             | 1                |
+[no-assign-spyon][]          | 0                |
 
 For example, using the recommended configuration, the `no-focused-tests` rule
 is enabled and will cause ESLint to throw an error (with an exit code of `1`)
@@ -73,13 +75,16 @@ rules:
 
 See [configuring rules][] for more information.
 
+[named-spy]: docs/rules/named-spy.md
 [no-focused-tests]: docs/rules/no-focused-tests.md
 [no-disabled-tests]: docs/rules/no-disabled-tests.md
-[no-spec-dupes]: docs/rules/no-spec-dupes.md
 [no-suite-dupes]: docs/rules/no-suite-dupes.md
-[no-suite-callback-args]: docs/rules/no-suite-callback-args.md
+[no-spec-dupes]: docs/rules/no-spec-dupes.md
 [missing-expect]: docs/rules/missing-expect.md
+[no-suite-callback-args]: docs/rules/no-suite-callback-args.md
 [valid-expect]: docs/rules/valid-expect.md
+[no-assign-spyon]: docs/rules/no-assign-spyon.md
+
 [configuring rules]: http://eslint.org/docs/user-guide/configuring#configuring-rules
 
 ## Author

docs/rules/no-assign-spyon.md

@@ -0,0 +1,20 @@
+# Disallow the assignment of a `spyOn` return value
+
+It is often more obvious to pass the spy as a property of the object spied upon
+instead of from a referencing variable.
+
+The following are considered warnings:
+
+```js
+var someSpy = spyOn(someObj, 'someMethod');
+// Handle someSpy, for example
+// expect(someSpy).toHaveBeenCalled();
+```
+
+The following are not warnings:
+
+```js
+spyOn(someObj, 'someMethod');
+// Handle someObj.someMethod, for example
+// expect(someObj.someMethod).toHaveBeenCalled();
+```

index.js

@@ -9,7 +9,8 @@ module.exports = {
     'no-spec-dupes': require('./lib/rules/no-spec-dupes'),
     'missing-expect': require('./lib/rules/missing-expect'),
     'no-suite-callback-args': require('./lib/rules/no-suite-callback-args'),
-    'valid-expect': require('./lib/rules/valid-expect')
+    'valid-expect': require('./lib/rules/valid-expect'),
+    'no-assign-spyon': require('./lib/rules/no-assign-spyon')
   },
   configs: {
     recommended: {
@@ -21,7 +22,8 @@ module.exports = {
         'no-spec-dupes': 1,
         'missing-expect': 0,
         'no-suite-callback-args': 2,
-        'valid-expect': 1
+        'valid-expect': 1,
+        'no-assign-spyon': 0
       }
     }
   }

lib/rules/no-assign-spyon.js

@@ -0,0 +1,16 @@
+'use strict'
+
+/**
+ * @fileoverview Disallow the assignment of a spyOn call result.
+ * @author Remco Haszing
+ */
+
+module.exports = function (context) {
+  return {
+    CallExpression: function (node) {
+      if (node.callee.name === 'spyOn' && (node.parent.type === 'AssignmentExpression' || node.parent.type === 'VariableDeclarator')) {
+        context.report(node, 'The result of spyOn() should not be assigned')
+      }
+    }
+  }
+}

test/rules/no-assign-spyon.js

@@ -0,0 +1,31 @@
+'use strict'
+
+var rule = require('../../lib/rules/no-assign-spyon')
+var RuleTester = require('eslint').RuleTester
+
+var eslintTester = new RuleTester()
+
+eslintTester.run('no-assign-spyon', rule, {
+  valid: [
+    'var result = someFunc()',
+    'result = someFunc()'
+  ],
+  invalid: [
+    {
+      code: 'var spy = spyOn(object, "property");',
+      errors: [
+        {
+          message: 'The result of spyOn() should not be assigned'
+        }
+      ]
+    },
+    {
+      code: 'spy = spyOn(object, "property");',
+      errors: [
+        {
+          message: 'The result of spyOn() should not be assigned'
+        }
+      ]
+    }
+  ]
+})