Add no-identical-title rule (fixes #33)

docs/rules/README.md

@@ -14,3 +14,4 @@
 * [no-hooks](no-hooks.md) - disallow hooks
 * [no-hooks-for-single-case](no-hooks-for-single-case.md) - disallow hooks for a single test or test suite
 * [no-top-level-hooks](no-top-level-hooks.md) - disallow top-level hooks
+* [no-identical-title](no-identical-title.md) - disallow identical titles

docs/rules/no-identical-title.md

@@ -0,0 +1,45 @@
+# Disallow identical titles (no-identical-title)
+
+Having identical titles for two different tests or test suites may create confusion. For example, when a test with the same title as another test in the same test suite fails, it is harder to know which one failed and thus harder to fix.
+
+## Rule Details
+
+This rule looks at the title of every test and test suites. It will report when two test suites or two test cases at the same level of a test suite have the same title.
+
+The following patterns are considered warnings:
+
+```js
+describe('foo', function () {
+    it('should do bar', function() {});
+    it('should do bar', function() {}); // Has the same title as the previous test
+
+    describe('baz', function() {
+        // ...
+    });
+
+    describe('baz', function() { // Has the same title as a previous test suite
+        // ...
+    });
+});
+```
+
+These patterns would not be considered warnings:
+
+```js
+describe('foo', function () {
+    it('should do foo', function() {});
+    it('should do bar', function() {});
+
+    // Has the same name as a parent test suite, which is fine
+    describe('foo', function() {
+        // Has the same name as a test in a parent test suite, which is fine
+        it('should do foo', function() {});
+        it('should work', function() {});
+    });
+
+    describe('baz', function() { // Has the same title as a previous test suite
+        // Has the same name as a test in a sibling test suite, which is fine
+        it('should work', function() {});
+    });
+});
+```

index.js

@@ -15,7 +15,8 @@ module.exports = {
         'no-hooks': require('./lib/rules/no-hooks'),
         'no-hooks-for-single-case': require('./lib/rules/no-hooks-for-single-case'),
         'no-sibling-hooks': require('./lib/rules/no-sibling-hooks'),
-        'no-top-level-hooks': require('./lib/rules/no-top-level-hooks')
+        'no-top-level-hooks': require('./lib/rules/no-top-level-hooks'),
+        'no-identical-title': require('./lib/rules/no-identical-title')
     },
     configs: {
         recommended: {

lib/rules/no-identical-title.js

@@ -0,0 +1,60 @@
+'use strict';
+
+var astUtil = require('../util/ast');
+
+function newLayer() {
+    return {
+        describeTitles: [],
+        testTitles: []
+    };
+}
+
+function handlTestCaseTitles(context, titles, node, title) {
+    if (astUtil.isTestCase(node)) {
+        if (titles.indexOf(title) !== -1) {
+            context.report({
+                node: node,
+                message: 'Test title is used multiple times in the same test suite.'
+            });
+        }
+        titles.push(title);
+    }
+}
+
+function handlTestSuiteTitles(context, layers, node, title) {
+    var currentLayer = layers[layers.length - 1];
+    if (astUtil.isDescribe(node)) {
+        if (currentLayer.describeTitles.indexOf(title) !== -1) {
+            context.report({
+                node: node,
+                message: 'Test suite title is used multiple times.'
+            });
+        }
+        currentLayer.describeTitles.push(title);
+        layers.push(newLayer());
+    }
+}
+
+module.exports = function (context) {
+    var titleLayers = [
+        newLayer()
+    ];
+    return {
+        CallExpression: function (node) {
+            var currentLayer = titleLayers[titleLayers.length - 1],
+                title;
+            if (!node.arguments || !node.arguments[0] || node.arguments[0].type !== 'Literal') {
+                return;
+            }
+
+            title = node.arguments[0].value;
+            handlTestCaseTitles(context, currentLayer.testTitles, node, title);
+            handlTestSuiteTitles(context, titleLayers, node, title);
+        },
+        'CallExpression:exit': function (node) {
+            if (astUtil.isDescribe(node)) {
+                titleLayers.pop();
+            }
+        }
+    };
+};

test/rules/no-identical-title.js

@@ -0,0 +1,139 @@
+'use strict';
+
+var RuleTester = require('eslint').RuleTester,
+    rules = require('../../').rules,
+    ruleTester = new RuleTester();
+
+ruleTester.run('no-identical-title', rules['no-identical-title'], {
+
+    valid: [
+        [
+            'describe("describe", function() {',
+            '   it("it", function() {});',
+            '});'
+        ].join('\n'),
+        [
+            'describe("describe1", function() {',
+            '   it("it1", function() {});',
+            '   it("it2", function() {});',
+            '});'
+        ].join('\n'),
+        [
+            'it("it1", function() {});',
+            'it("it2", function() {});'
+        ].join('\n'),
+        [
+            'it.only("it1", function() {});',
+            'it("it2", function() {});'
+        ].join('\n'),
+        [
+            'it.only("it1", function() {});',
+            'it.only("it2", function() {});'
+        ].join('\n'),
+        [
+            'describe("title", function() {});',
+            'it("title", function() {});'
+        ].join('\n'),
+        [
+            'describe("describe1", function() {',
+            '   it("it1", function() {});',
+            '   describe("describe2", function() {',
+            '       it("it1", function() {});',
+            '   });',
+            '});'
+        ].join('\n'),
+        [
+            'describe("describe1", function() {',
+            '   describe("describe2", function() {',
+            '       it("it1", function() {});',
+            '   });',
+            '   it("it1", function() {});',
+            '});'
+        ].join('\n'),
+        [
+            'describe("describe1", function() {',
+            '   describe("describe2", function() {});',
+            '});'
+        ].join('\n'),
+        [
+            'describe("describe1", function() {',
+            '   describe("describe2", function() {});',
+            '});',
+            'describe("describe2", function() {});'
+        ].join('\n'),
+        [
+            'describe("describe1", function() {});',
+            'describe("describe2", function() {});'
+        ].join('\n'),
+        [
+            'it("it" + n, function() {});',
+            'it("it" + n, function() {});'
+        ].join('\n'),
+        {
+            code: [
+                'it(`it${n}`, function() {});',
+                'it(`it${n}`, function() {});'
+            ].join('\n'),
+            env: {
+                es6: true
+            }
+        }
+    ],
+
+    invalid: [
+        {
+            code: [
+                'describe("describe1", function() {',
+                '   it("it1", function() {});',
+                '   it("it1", function() {});',
+                '});'
+            ].join('\n'),
+            errors: [ { message: 'Test title is used multiple times in the same test suite.', column: 4, line: 3 } ]
+        },
+        {
+            code: [
+                'it("it1", function() {});',
+                'it("it1", function() {});'
+            ].join('\n'),
+            errors: [ { message: 'Test title is used multiple times in the same test suite.', column: 1, line: 2 } ]
+        },
+        {
+            code: [
+                'it.only("it1", function() {});',
+                'it("it1", function() {});'
+            ].join('\n'),
+            errors: [ { message: 'Test title is used multiple times in the same test suite.', column: 1, line: 2 } ]
+        },
+        {
+            code: [
+                'it.only("it1", function() {});',
+                'it.only("it1", function() {});'
+            ].join('\n'),
+            errors: [ { message: 'Test title is used multiple times in the same test suite.', column: 1, line: 2 } ]
+        },
+        {
+            code: [
+                'it("it1", function() {});',
+                'specify("it1", function() {});'
+            ].join('\n'),
+            errors: [ { message: 'Test title is used multiple times in the same test suite.', column: 1, line: 2 } ]
+        },
+        {
+            code: [
+                'describe("describe1", function() {});',
+                'describe("describe1", function() {});'
+            ].join('\n'),
+            errors: [ { message: 'Test suite title is used multiple times.', column: 1, line: 2 } ]
+        },
+        {
+            code: [
+                'describe("describe1", function() {',
+                '   describe("describe2", function() {});',
+                '});',
+                'describe("describe1", function() {});'
+            ].join('\n'),
+            errors: [ { message: 'Test suite title is used multiple times.', column: 1, line: 4 } ]
+        }
+    ]
+
+});