feat(rules): add 'empty-script' rule

#86

README.md

@@ -64,6 +64,7 @@ There are various types of rules implemented in the plugin. Here is a rough cate
 * [no-get-location-abs-url][]: Warn about using deprecated `getLocationAbsUrl()` method
 * [no-promise-in-if][]: Warn if promise is checked for truthiness inside an `if` condition
 * [bare-element-finders][]: Warn if a bare `ElementFinder` or `ElementArrayFinder` is declared with no applied action
+* [empty-script][]: Warn if `executeScript()` or `executeAsyncScript()` are called with missing or empty script
 
 #### Locating Elements
 
@@ -137,6 +138,7 @@ Rule                         | Default Error Level | Auto-fixable | Options
 [valid-by-tagname][]         | 1                   |              |
 [limit-selector-depth][]     | 1                   |              | number of nodes (default 5)
 [bare-element-finders][]     | 1                   |              | 
+[empty-script][]             | 1                   |              |
 [use-promise-all][]          | 0 (Turned off)      |              |
 [by-css-shortcut][]          | 0                   |              |
 [no-browser-driver][]        | 0                   |              |
@@ -195,6 +197,7 @@ See [configuring rules][] for more information.
 [no-get-raw-id]: docs/rules/no-get-raw-id.md
 [no-get-location-abs-url]: docs/rules/no-get-location-abs-url.md
 [bare-element-finders]: docs/rules/bare-element-finders.md
+[empty-script]: docs/rules/empty-script.md
 [configuring rules]: http://eslint.org/docs/user-guide/configuring#configuring-rules
 
 ## Recommended configuration

docs/rules/empty-script.md

@@ -0,0 +1,23 @@
+# Warn if `executeScript()` or `executeAsyncScript()` are called with missing or empty script
+
+This is a simple rule that would warn if `executeScript()`/`executeAsyncScript()` calls are missing arguments, or if the first argument is an empty string.
+
+## Rule details
+
+:thumbsdown: Any use of the following patterns are considered warnings:
+
+```js
+browser.executeScript();
+browser.executeAsyncScript();
+browser.executeScript("");
+browser.executeAsyncScript('');
+```
+
+:thumbsup: The following patterns are not errors:
+
+```js
+browser.executeScript("var a = 1;");
+browser.executeAsyncScript("var a = 1;");
+var tag = browser.executeScript('return arguments[0].tagName', el);
+browser.executeAsyncScript('var callback = arguments[arguments.length - 1];');
+```

index.js

@@ -37,6 +37,7 @@ var noGetRawId = require('./lib/rules/no-get-raw-id')
 var noGetLocationAbsUrl = require('./lib/rules/no-get-location-abs-url')
 var limitSelectorDepth = require('./lib/rules/limit-selector-depth')
 var bareElementFinders = require('./lib/rules/bare-element-finders')
+var emptyScript = require('./lib/rules/empty-script')
 
 module.exports = {
   rules: {
@@ -76,7 +77,8 @@ module.exports = {
     'no-get-raw-id': noGetRawId,
     'no-get-location-abs-url': noGetLocationAbsUrl,
     'limit-selector-depth': limitSelectorDepth,
-    'bare-element-finders': bareElementFinders
+    'bare-element-finders': bareElementFinders,
+    'empty-script': emptyScript
   },
   configs: {
     recommended: {
@@ -115,6 +117,7 @@ module.exports = {
         'protractor/limit-selector-depth': 1,
         'protractor/no-get-location-abs-url': 1,
         'protractor/bare-element-finders': 1,
+        'protractor/empty-script': 1,
         'protractor/use-promise-all': 0,
         'protractor/by-css-shortcut': 0,
         'protractor/no-browser-driver': 0

lib/rules/empty-script.js

@@ -0,0 +1,44 @@
+'use strict'
+
+/**
+ * @fileoverview Warn if `executeScript()` or `executeAsyncScript()` are called with no arguments
+ * @author Alexander Afanasyev
+ */
+
+module.exports = {
+  meta: {
+    schema: []
+  },
+
+  create: function (context) {
+    return {
+      'CallExpression': function (node) {
+        var object = node.callee.object
+        var property = node.callee.property
+
+        if (object && property && object.name === 'browser') {
+          if (property.name === 'executeScript' || property.name === 'executeAsyncScript') {
+            var argumentExists = node.arguments && node.arguments.length
+
+            if (!argumentExists) {
+              context.report({
+                node: property,
+                message: property.name + '() call without arguments'
+              })
+
+              return
+            }
+
+            var firstArgumentNonEmpty = argumentExists && node.arguments[0].value
+            if (!firstArgumentNonEmpty) {
+              context.report({
+                node: property,
+                message: property.name + '() called with an empty script'
+              })
+            }
+          }
+        }
+      }
+    }
+  }
+}

test/rules/empty-script.js

@@ -0,0 +1,42 @@
+'use strict'
+
+var rule = require('../../lib/rules/empty-script')
+var RuleTester = require('eslint').RuleTester
+
+var eslintTester = new RuleTester()
+
+eslintTester.run('empty-script', rule, {
+  valid: [
+    'browser.executeScript("var a = 1;");',
+    'browser.executeAsyncScript("var a = 1;");',
+    'var tag = browser.executeScript("return arguments[0].tagName", el);',
+    'browser.executeAsyncScript("var callback = arguments[arguments.length - 1];");'
+  ],
+
+  invalid: [
+    {
+      code: 'browser.executeScript();',
+      errors: [{
+        message: 'executeScript() call without arguments'
+      }]
+    },
+    {
+      code: 'browser.executeAsyncScript();',
+      errors: [{
+        message: 'executeAsyncScript() call without arguments'
+      }]
+    },
+    {
+      code: 'browser.executeScript("");',
+      errors: [{
+        message: 'executeScript() called with an empty script'
+      }]
+    },
+    {
+      code: 'browser.executeAsyncScript("");',
+      errors: [{
+        message: 'executeAsyncScript() called with an empty script'
+      }]
+    }
+  ]
+})