feat(eslint-plugin): add ban-ts-ignore rule (#276)

* feat(eslint-plugin): add ban-ts-ignore rule

* test(eslint-plugin): add more tests

packages/eslint-plugin/README.md

@@ -113,6 +113,7 @@ Then you should add `airbnb` (or `airbnb-base`) to your `extends` section of `.e
 | [`@typescript-eslint/adjacent-overload-signatures`](./docs/rules/adjacent-overload-signatures.md)         | Require that member overloads be consecutive (`adjacent-overload-signatures` from TSLint)                                                           | :heavy_check_mark: |          |
 | [`@typescript-eslint/array-type`](./docs/rules/array-type.md)                                             | Requires using either `T[]` or `Array<T>` for arrays (`array-type` from TSLint)                                                                     | :heavy_check_mark: | :wrench: |
 | [`@typescript-eslint/ban-types`](./docs/rules/ban-types.md)                                               | Enforces that types will not to be used (`ban-types` from TSLint)                                                                                   | :heavy_check_mark: | :wrench: |
+| [`@typescript-eslint/ban-ts-ignore`](./docs/rules/ban-ts-ignore.md)                                       | Bans “// @ts-ignore” comments from being used (`ban-ts-ignore` from TSLint)                                                                         | :heavy_check_mark: |          |
 | [`@typescript-eslint/camelcase`](./docs/rules/camelcase.md)                                               | Enforce camelCase naming convention                                                                                                                 | :heavy_check_mark: |          |
 | [`@typescript-eslint/class-name-casing`](./docs/rules/class-name-casing.md)                               | Require PascalCased class and interface names (`class-name` from TSLint)                                                                            | :heavy_check_mark: |          |
 | [`@typescript-eslint/explicit-function-return-type`](./docs/rules/explicit-function-return-type.md)       | Require explicit return types on functions and class methods                                                                                        | :heavy_check_mark: |          |

packages/eslint-plugin/ROADMAP.md

@@ -13,7 +13,7 @@
 | TSLint rule                       |     | ESLint rule                                          |
 | --------------------------------- | :-: | ---------------------------------------------------- |
 | [`adjacent-overload-signatures`]  | ✅  | [`@typescript-eslint/adjacent-overload-signatures`]  |
-| [`ban-ts-ignore`]                 | 🛑  | N/A                                                  |
+| [`ban-ts-ignore`]                 | ✅  | [`@typescript-eslint/ban-ts-ignore`]                 |
 | [`ban-types`]                     | ✅  | [`@typescript-eslint/ban-types`]                     |
 | [`member-access`]                 | ✅  | [`@typescript-eslint/explicit-member-accessibility`] |
 | [`member-ordering`]               | ✅  | [`@typescript-eslint/member-ordering`]               |
@@ -575,6 +575,7 @@ Relevant plugins: [`chai-expect-keywords`](https://github.com/gavinaiken/eslint-
 
 [`@typescript-eslint/adjacent-overload-signatures`]: https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/adjacent-overload-signatures.md
 [`@typescript-eslint/ban-types`]: https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/ban-types.md
+[`@typescript-eslint/ban-ts-ignore`]: https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/ban-ts-ignore.md
 [`@typescript-eslint/explicit-member-accessibility`]: https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/explicit-member-accessibility.md
 [`@typescript-eslint/member-ordering`]: https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/member-ordering.md
 [`@typescript-eslint/no-explicit-any`]: https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/no-explicit-any.md

packages/eslint-plugin/docs/rules/ban-ts-ignore.md

@@ -0,0 +1,37 @@
+# Bans “// @ts-ignore” comments from being used (ban-ts-ignore)
+
+Suppressing Typescript Compiler Errors can be hard to discover.
+
+## Rule Details
+
+Does not allow the use of `// @ts-ignore` comments.
+
+The following patterns are considered warnings:
+
+```ts
+if (false) {
+  // @ts-ignore: Unreachable code error
+  console.log('hello');
+}
+```
+
+The following patterns are not warnings:
+
+```ts
+if (false) {
+  // Compiler warns about unreachable code error
+  console.log('hello');
+}
+```
+
+## When Not To Use It
+
+If you are sure, compiler errors won't affect functionality and you need to disable them.
+
+## Further Reading
+
+- TypeScript [Type Checking JavaScript Files](https://www.typescriptlang.org/docs/handbook/type-checking-javascript-files.html)
+
+## Compatibility
+
+- TSLint: [ban-ts-ignore](https://palantir.github.io/tslint/rules/ban-ts-ignore/)

packages/eslint-plugin/src/rules/ban-ts-ignore.ts

@@ -0,0 +1,47 @@
+/**
+ * @fileoverview Bans “// @ts-ignore” comments from being used.
+ * @author Ricky Lippmann <https://github.com/ldrick>
+ */
+
+import * as util from '../util';
+
+export default util.createRule({
+  name: 'ban-ts-ignore',
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'Bans “// @ts-ignore” comments from being used.',
+      tslintRuleName: 'ban-ts-ignore',
+      category: 'Best Practices',
+      recommended: 'error'
+    },
+    schema: [],
+    messages: {
+      tsIgnoreComment:
+        'Do not use "// @ts-ignore" comments because they suppress compilation errors.'
+    }
+  },
+  defaultOptions: [],
+  create(context) {
+    const tsIgnoreRegExp = /^\/*\s*@ts-ignore/;
+    const sourceCode = context.getSourceCode();
+
+    return {
+      Program(): void {
+        const comments = sourceCode.getAllComments();
+
+        comments.forEach(comment => {
+          if (comment.type !== 'Line') {
+            return;
+          }
+          if (tsIgnoreRegExp.test(comment.value)) {
+            context.report({
+              node: comment,
+              messageId: 'tsIgnoreComment'
+            });
+          }
+        });
+      }
+    };
+  }
+});

packages/eslint-plugin/tests/rules/ban-ts-ignore.test.ts

@@ -0,0 +1,65 @@
+import rule from '../../src/rules/ban-ts-ignore';
+import { RuleTester } from '../RuleTester';
+
+const ruleTester = new RuleTester({
+  parser: '@typescript-eslint/parser'
+});
+
+ruleTester.run('ban-ts-ignore', rule, {
+  valid: [
+    `// just a comment containing @ts-ignore somewhere`,
+    `/* @ts-ignore */`,
+    `/** @ts-ignore */`,
+    `/*
+// @ts-ignore in a block
+*/`
+  ],
+  invalid: [
+    {
+      code: '// @ts-ignore',
+      errors: [
+        {
+          messageId: 'tsIgnoreComment',
+          line: 1,
+          column: 1
+        }
+      ]
+    },
+    {
+      code: '// @ts-ignore: Suppress next line',
+      errors: [
+        {
+          messageId: 'tsIgnoreComment',
+          line: 1,
+          column: 1
+        }
+      ]
+    },
+    {
+      code: '/////@ts-ignore: Suppress next line',
+      errors: [
+        {
+          messageId: 'tsIgnoreComment',
+          line: 1,
+          column: 1
+        }
+      ]
+    },
+    {
+      code: `
+if (false) {
+  // @ts-ignore: Unreachable code error
+  console.log("hello");
+}
+            `,
+      parser: '@typescript-eslint/parser',
+      errors: [
+        {
+          messageId: 'tsIgnoreComment',
+          line: 3,
+          column: 3
+        }
+      ]
+    }
+  ]
+});