feat(rules): Add no-empty-title rule (#238)

Fixes #226

README.md

@@ -96,6 +96,7 @@ for more information about extending configuration files.
 | [lowercase-name][]           | Disallow capitalized test names                                   |                  | ![fixable-green][]  |
 | [no-alias-methods][]         | Disallow alias methods                                            | ![recommended][] | ![fixable-green][]  |
 | [no-disabled-tests][]        | Disallow disabled tests                                           | ![recommended][] |                     |
+| [no-empty-title][]           | Disallow empty titles                                             |                  |                     |
 | [no-focused-tests][]         | Disallow focused tests                                            | ![recommended][] |                     |
 | [no-hooks][]                 | Disallow setup and teardown hooks                                 |                  |                     |
 | [no-identical-title][]       | Disallow identical titles                                         | ![recommended][] |                     |
@@ -131,6 +132,7 @@ for more information about extending configuration files.
 [lowercase-name]: docs/rules/lowercase-name.md
 [no-alias-methods]: docs/rules/no-alias-methods.md
 [no-disabled-tests]: docs/rules/no-disabled-tests.md
+[no-empty-title]: docs/rules/no-empty-title.md
 [no-focused-tests]: docs/rules/no-focused-tests.md
 [no-hooks]: docs/rules/no-hooks.md
 [no-identical-title]: docs/rules/no-identical-title.md

docs/rules/no-empty-title.md

@@ -0,0 +1,36 @@
+# Disallow empty titles
+
+Having an empty string as your test title is pretty useless. This rule reports
+an error if it finds an empty string as s test title.
+
+This rule is not auto-fixable.
+
+## Rule Details
+
+The following patterns are considered warnings:
+
+```js
+describe('', () => {});
+describe('foo', () => {
+  it('', () => {});
+});
+it('', () => {});
+test('', () => {});
+xdescribe('', () => {});
+xit('', () => {});
+xtest('', () => {});
+```
+
+These patterns would not be considered warnings:
+
+```js
+describe('foo', () => {});
+describe('foo', () => {
+  it('bar', () => {});
+});
+test('foo', () => {});
+it('foo', () => {});
+xdescribe('foo', () => {});
+xit('foo', () => {});
+xtest('foo', () => {});
+```

rules/__tests__/no-empty-title.js

@@ -0,0 +1,108 @@
+'use strict';
+
+const { RuleTester } = require('eslint');
+const rule = require('../no-empty-title');
+
+const ruleTester = new RuleTester({
+  parserOptions: {
+    sourceType: 'module',
+  },
+});
+
+ruleTester.run('no-empty-title', rule, {
+  valid: [
+    'someFn("", function () {})',
+    'describe(1, function () {})',
+    'describe("foo", function () {})',
+    'describe("foo", function () { it("bar", function () {}) })',
+    'test("foo", function () {})',
+    'test(`foo`, function () {})',
+    'test(`${foo}`, function () {})',
+    "it('foo', function () {})",
+    "xdescribe('foo', function () {})",
+    "xit('foo', function () {})",
+    "xtest('foo', function () {})",
+  ],
+  invalid: [
+    {
+      code: 'describe("", function () {})',
+      errors: [
+        {
+          message: rule.errorMessages.describe,
+          column: 1,
+          line: 1,
+        },
+      ],
+    },
+    {
+      code: ["describe('foo', () => {", "it('', () => {})", '})'].join('\n'),
+      errors: [
+        {
+          message: rule.errorMessages.test,
+          column: 1,
+          line: 2,
+        },
+      ],
+    },
+    {
+      code: 'it("", function () {})',
+      errors: [
+        {
+          message: rule.errorMessages.test,
+          column: 1,
+          line: 1,
+        },
+      ],
+    },
+    {
+      code: 'test("", function () {})',
+      errors: [
+        {
+          message: rule.errorMessages.test,
+          column: 1,
+          line: 1,
+        },
+      ],
+    },
+    {
+      code: 'test(``, function () {})',
+      errors: [
+        {
+          message: rule.errorMessages.test,
+          column: 1,
+          line: 1,
+        },
+      ],
+    },
+    {
+      code: "xdescribe('', () => {})",
+      errors: [
+        {
+          message: rule.errorMessages.describe,
+          column: 1,
+          line: 1,
+        },
+      ],
+    },
+    {
+      code: "xit('', () => {})",
+      errors: [
+        {
+          message: rule.errorMessages.test,
+          column: 1,
+          line: 1,
+        },
+      ],
+    },
+    {
+      code: "xtest('', () => {})",
+      errors: [
+        {
+          message: rule.errorMessages.test,
+          column: 1,
+          line: 1,
+        },
+      ],
+    },
+  ],
+});

rules/__tests__/no-identical-title.test.js

@@ -69,6 +69,12 @@ ruleTester.run('no-identical-title', rule, {
         es6: true,
       },
     },
+    {
+      code: 'it(`${n}`, function() {});',
+      env: {
+        es6: true,
+      },
+    },
     [
       'describe("title " + foo, function() {',
       '    describe("describe1", function() {});',

rules/no-empty-title.js

@@ -0,0 +1,54 @@
+'use strict';
+
+const {
+  getDocsUrl,
+  hasExpressions,
+  isDescribe,
+  isTestCase,
+  isTemplateLiteral,
+  isString,
+  getStringValue,
+} = require('./util');
+
+const errorMessages = {
+  describe: 'describe should not have an empty title',
+  test: 'test should not have an empty title',
+};
+
+module.exports = {
+  meta: {
+    docs: {
+      url: getDocsUrl(__filename),
+    },
+  },
+  create(context) {
+    return {
+      CallExpression(node) {
+        const is = {
+          describe: isDescribe(node),
+          testCase: isTestCase(node),
+        };
+        if (!is.describe && !is.testCase) {
+          return;
+        }
+        const [firstArgument] = node.arguments;
+        if (!isString(firstArgument)) {
+          return;
+        }
+        if (isTemplateLiteral(firstArgument) && hasExpressions(firstArgument)) {
+          return;
+        }
+        if (getStringValue(firstArgument) === '') {
+          const message = is.describe
+            ? errorMessages.describe
+            : errorMessages.test;
+          context.report({
+            message,
+            node,
+          });
+        }
+      },
+    };
+  },
+  errorMessages,
+};

rules/no-identical-title.js

@@ -6,6 +6,7 @@ const {
   isTestCase,
   isString,
   hasExpressions,
+  getStringValue,
 } = require('./util');
 
 const newDescribeContext = () => ({
@@ -50,14 +51,6 @@ const isFirstArgValid = arg => {
   return true;
 };
 
-const getArgValue = arg => {
-  if (arg.type === 'TemplateLiteral') {
-    return arg.quasis[0].value.raw;
-  }
-
-  return arg.value;
-};
-
 module.exports = {
   meta: {
     docs: {
@@ -76,7 +69,7 @@ module.exports = {
         if (!isFirstArgValid(firstArgument)) {
           return;
         }
-        const title = getArgValue(firstArgument);
+        const title = getStringValue(firstArgument);
         handleTestCaseTitles(context, currentLayer.testTitles, node, title);
         handleDescribeBlockTitles(
           context,

rules/util.js

@@ -132,10 +132,15 @@ const isFunction = node =>
 
 const isString = node =>
   (node.type === 'Literal' && typeof node.value === 'string') ||
-  node.type === 'TemplateLiteral';
+  isTemplateLiteral(node);
+
+const isTemplateLiteral = node => node.type === 'TemplateLiteral';
 
 const hasExpressions = node => node.expressions && node.expressions.length > 0;
 
+const getStringValue = arg =>
+  isTemplateLiteral(arg) ? arg.quasis[0].value.raw : arg.value;
+
 /**
  * Generates the URL to documentation for the given rule name. It uses the
  * package version to build the link to a tagged version of the
@@ -210,8 +215,10 @@ module.exports = {
   expectToEqualCase,
   expectNotToEqualCase,
   getNodeName,
+  getStringValue,
   isDescribe,
   isFunction,
+  isTemplateLiteral,
   isTestCase,
   isString,
   hasExpressions,