Add prefer-to-be-defined rule

CHANGELOG.md

@@ -17,6 +17,8 @@ project adheres to [Semantic Versioning](http://semver.org/).
   ([#10](https://github.com/jest-community/eslint-plugin-jest/pull/10))
 * Add `prefer-to-be-undefined` rule
   ([#9](https://github.com/jest-community/eslint-plugin-jest/pull/9))
+* Add `prefer-to-be-defined` rule
+  ([#8](https://github.com/jest-community/eslint-plugin-jest/pull/8))
 
 ## [21.3.2] - 2017-11-09
 

README.md

@@ -1,4 +1,5 @@
-[![Build Status](https://travis-ci.org/jest-community/eslint-plugin-jest.svg?branch=master)](https://travis-ci.org/jest-community/eslint-plugin-jest) [![Greenkeeper badge](https://badges.greenkeeper.io/jest-community/eslint-plugin-jest.svg)](https://greenkeeper.io/)
+[![Build Status](https://travis-ci.org/jest-community/eslint-plugin-jest.svg?branch=master)](https://travis-ci.org/jest-community/eslint-plugin-jest)
+[![Greenkeeper badge](https://badges.greenkeeper.io/jest-community/eslint-plugin-jest.svg)](https://greenkeeper.io/)
 
 <div align="center">
   <a href="https://eslint.org/">
@@ -66,6 +67,8 @@ You can also whitelist the environment variables provided by Jest by doing:
   `toBeNull()`.
 * [prefer-to-be-undefined](/docs/rules/prefer-to-be-undefined.md) - suggest
   using `toBeUndefined()`.
+* [prefer-to-be-defined](/docs/rules/prefer-to-be-defined.md) - suggest using
+  `toBeDefined()`.
 * [prefer-to-have-length](/docs/rules/prefer-to-have-length.md) - suggest using
   `toHaveLength()`.
 * [valid-expect](/docs/rules/valid-expect.md) - ensure expect is called

docs/rules/prefer-to-be-defined.md

@@ -0,0 +1,29 @@
+# Suggest using `toBeDefined()` (prefer-to-be-defined)
+
+In order to have a better failure message, `toBeDefined()` should be used upon
+asserting expections on defined value.
+
+## Rule details
+
+This rule triggers a warning if `not.toBe()` is used to assert a undefined
+value.
+
+```js
+expect(true).not.toBe(undefined);
+```
+
+This rule is enabled by default.
+
+### Default configuration
+
+The following patterns are considered warning:
+
+```js
+expect(true).not.toBeUndefined();
+```
+
+The following pattern is not warning:
+
+```js
+expect(true).toBeDefined();
+```

index.js

@@ -5,6 +5,7 @@ const noFocusedTests = require('./rules/no_focused_tests');
 const noIdenticalTitle = require('./rules/no_identical_title');
 const preferToBeNull = require('./rules/prefer_to_be_null');
 const preferToBeUndefined = require('./rules/prefer_to_be_undefined');
+const preferToBeDefined = require('./rules/prefer_to_be_defined');
 const preferToHaveLength = require('./rules/prefer_to_have_length');
 const validExpect = require('./rules/valid_expect');
 
@@ -49,6 +50,7 @@ module.exports = {
     'no-identical-title': noIdenticalTitle,
     'prefer-to-be-null': preferToBeNull,
     'prefer-to-be-undefined': preferToBeUndefined,
+    'prefer-to-be-defined': preferToBeDefined,
     'prefer-to-have-length': preferToHaveLength,
     'valid-expect': validExpect,
   },

rules/__tests__/prefer_to_be_defined.test.js

@@ -0,0 +1,35 @@
+'use strict';
+
+const RuleTester = require('eslint').RuleTester;
+const rules = require('../../').rules;
+
+const ruleTester = new RuleTester();
+
+ruleTester.run('prefer_to_be_defined', rules['prefer-to-be-defined'], {
+  valid: ['expect(true).toBeDefined();'],
+
+  invalid: [
+    {
+      code: 'expect(true).not.toEqual(undefined);',
+      errors: [
+        {
+          message: 'Use toBeDefined() instead',
+          column: 14,
+          line: 1,
+        },
+      ],
+      output: 'expect(true).toBeDefined();',
+    },
+    {
+      code: 'expect(true).not.toBeUndefined();',
+      errors: [
+        {
+          message: 'Use toBeDefined() instead',
+          column: 14,
+          line: 1,
+        },
+      ],
+      output: 'expect(true).toBeDefined();',
+    },
+  ],
+});

rules/prefer_to_be_defined.js

@@ -0,0 +1,54 @@
+'use strict';
+
+module.exports = context => {
+  return {
+    CallExpression(node) {
+      const calleeName = node.callee.name;
+
+      if (
+        calleeName === 'expect' &&
+        node.arguments.length == 1 &&
+        node.parent &&
+        node.parent.type === 'MemberExpression' &&
+        node.parent.parent &&
+        node.parent.parent.type === 'MemberExpression'
+      ) {
+        const parentProperty = node.parent.property;
+        const propertyName = parentProperty.name;
+        const parentProperty2 = node.parent.parent.property;
+        const propertyName2 = parentProperty2.name;
+        const argument = node.parent.parent.parent.arguments[0];
+
+        if (
+          (propertyName === 'not' &&
+            (propertyName2 === 'toBe' || propertyName2 === 'toEqual') &&
+            argument.value === undefined) ||
+          (propertyName === 'not' && propertyName2 === 'toBeUndefined')
+        ) {
+          context.report({
+            fix(fixer) {
+              const propertyDot = context
+                .getSourceCode()
+                .getFirstTokenBetween(
+                  parentProperty,
+                  parentProperty2,
+                  token => token.value === '.'
+                );
+              const fixes = [
+                fixer.remove(parentProperty),
+                fixer.remove(propertyDot),
+                fixer.replaceText(parentProperty2, 'toBeDefined'),
+              ];
+              if (argument) {
+                fixes.push(fixer.remove(argument));
+              }
+              return fixes;
+            },
+            message: 'Use toBeDefined() instead',
+            node: parentProperty,
+          });
+        }
+      }
+    },
+  };
+};