feat(lowercase-name): add 'ignore' option (#92)

Fixes #76

Author: with-heart

Diff for: docs/rules/lowercase-name.md

@@ -21,3 +21,52 @@ it('adds 1 + 2 to equal 3', () => {
   expect(sum(1, 2)).toBe(3);
 });
 ```
+
+## Options
+
+```json
+{
+  "jest/lowercase-name": [
+    "error",
+    {
+      "ignore": ["describe", "test"]
+    }
+  ]
+}
+```
+
+### `ignore`
+
+This array option whitelists function names so that this rule does not report
+their usage as being incorrect. There are three possible values:
+
+* `"describe"`
+* `"test"`
+* `"it"`
+
+By default, none of these options are enabled (the equivalent of
+`{ "ignore": [] }`).
+
+Example of **correct** code for the `{ "ignore": ["describe"] }` option:
+
+```js
+/* eslint jest/lowercase-name: ["error", { "ignore": ["describe"] }] */
+
+describe('Uppercase description');
+```
+
+Example of **correct** code for the `{ "ignore": ["test"] }` option:
+
+```js
+/* eslint jest/lowercase-name: ["error", { "ignore": ["test"] }] */
+
+test('Uppercase description');
+```
+
+Example of **correct** code for the `{ "ignore": ["it"] }` option:
+
+```js
+/* eslint jest/lowercase-name: ["error", { "ignore": ["it"] }] */
+
+it('Uppercase description');
+```

Diff for: rules/__tests__/lowercase-name.test.js

@@ -11,6 +11,7 @@ const ruleTester = new RuleTester({
 
 ruleTester.run('lowercase-name', rule, {
   valid: [
+    'it()',
     "it(' ', function () {})",
     'it(" ", function () {})',
     'it(` `, function () {})',
@@ -20,12 +21,14 @@ ruleTester.run('lowercase-name', rule, {
     'it("<Foo/>", function () {})',
     'it("123 foo", function () {})',
     'it(42, function () {})',
+    'test()',
     "test('foo', function () {})",
     'test("foo", function () {})',
     'test(`foo`, function () {})',
     'test("<Foo/>", function () {})',
     'test("123 foo", function () {})',
     'test("42", function () {})',
+    'describe()',
     "describe('foo', function () {})",
     'describe("foo", function () {})',
     'describe(`foo`, function () {})',
@@ -128,3 +131,57 @@ ruleTester.run('lowercase-name', rule, {
     },
   ],
 });
+
+ruleTester.run('lowercase-name with ignore=describe', rule, {
+  valid: [
+    {
+      code: "describe('Foo', function () {})",
+      options: [{ ignore: ['describe'] }],
+    },
+    {
+      code: 'describe("Foo", function () {})',
+      options: [{ ignore: ['describe'] }],
+    },
+    {
+      code: 'describe(`Foo`, function () {})',
+      options: [{ ignore: ['describe'] }],
+    },
+  ],
+  invalid: [],
+});
+
+ruleTester.run('lowercase-name with ignore=test', rule, {
+  valid: [
+    {
+      code: "test('Foo', function () {})",
+      options: [{ ignore: ['test'] }],
+    },
+    {
+      code: 'test("Foo", function () {})',
+      options: [{ ignore: ['test'] }],
+    },
+    {
+      code: 'test(`Foo`, function () {})',
+      options: [{ ignore: ['test'] }],
+    },
+  ],
+  invalid: [],
+});
+
+ruleTester.run('lowercase-name with ignore=it', rule, {
+  valid: [
+    {
+      code: "it('Foo', function () {})",
+      options: [{ ignore: ['it'] }],
+    },
+    {
+      code: 'it("Foo", function () {})',
+      options: [{ ignore: ['it'] }],
+    },
+    {
+      code: 'it(`Foo`, function () {})',
+      options: [{ ignore: ['it'] }],
+    },
+  ],
+  invalid: [],
+});

Diff for: rules/lowercase-name.js

@@ -54,11 +54,20 @@ module.exports = {
     },
   },
   create(context) {
+    const ignore = (context.options[0] && context.options[0].ignore) || [];
+    const ignoredFunctionNames = ignore.reduce((accumulator, value) => {
+      accumulator[value] = true;
+      return accumulator;
+    }, Object.create(null));
+
+    const isIgnoredFunctionName = node =>
+      ignoredFunctionNames[node.callee.name];
+
     return {
       CallExpression(node) {
         const erroneousMethod = descriptionBeginsWithLowerCase(node);
 
-        if (erroneousMethod) {
+        if (erroneousMethod && !isIgnoredFunctionName(node)) {
           context.report({
             message: '`{{ method }}`s should begin with lowercase',
             data: { method: erroneousMethod },