feat(eslint-plugin): add extension rule space-before-blocks (#1606) (…

…#4184)

Co-authored-by: Josh Goldberg <me@joshuakgoldberg.com>

packages/eslint-plugin/README.md

@@ -231,6 +231,7 @@ In these cases, we create what we call an extension rule; a rule within our plug
 | [`@typescript-eslint/require-await`](./docs/rules/require-await.md)                                     | Disallow async functions which have no `await` expression                            | :white_check_mark: |          | :thought_balloon: |
 | [`@typescript-eslint/return-await`](./docs/rules/return-await.md)                                       | Enforces consistent returning of awaited values                                      |                    | :wrench: | :thought_balloon: |
 | [`@typescript-eslint/semi`](./docs/rules/semi.md)                                                       | Require or disallow semicolons instead of ASI                                        |                    | :wrench: |                   |
+| [`@typescript-eslint/space-before-blocks`](./docs/rules/space-before-blocks.md)                         | Enforces consistent spacing before blocks                                            |                    | :wrench: |                   |
 | [`@typescript-eslint/space-before-function-paren`](./docs/rules/space-before-function-paren.md)         | Enforces consistent spacing before function parenthesis                              |                    | :wrench: |                   |
 | [`@typescript-eslint/space-infix-ops`](./docs/rules/space-infix-ops.md)                                 | This rule is aimed at ensuring there are spaces around infix operators.              |                    | :wrench: |                   |
 

packages/eslint-plugin/docs/rules/space-before-blocks.md

@@ -0,0 +1,60 @@
+# `space-before-blocks`
+
+Enforces consistent spacing before blocks.
+
+## Rule Details
+
+This rule extends the base [`eslint/space-before-blocks`](https://eslint.org/docs/rules/space-before-blocks) rule.
+It adds support for interfaces and enums:
+
+### ❌ Incorrect
+
+```ts
+enum Breakpoint{
+  Large, Medium;
+}
+
+interface State{
+  currentBreakpoint: Breakpoint;
+}
+```
+
+### ✅ Correct
+
+```ts
+enum Breakpoint {
+  Large, Medium;
+}
+
+interface State {
+  currentBreakpoint: Breakpoint;
+}
+```
+
+In case a more specific options object is passed these blocks will follow `classes` configuration option.
+
+## How to Use
+
+```jsonc
+{
+  // note you must disable the base rule as it can report incorrect errors
+  "space-before-blocks": "off",
+  "@typescript-eslint/space-before-blocks": ["error"]
+}
+```
+
+## Options
+
+See [`eslint/space-before-blocks` options](https://eslint.org/docs/rules/space-before-blocks#options).
+
+<sup>
+
+Taken with ❤️ [from ESLint core](https://github.com/eslint/eslint/blob/master/docs/rules/space-before-blocks.md)
+
+</sup>
+
+## Attributes
+
+- [ ] ✅ Recommended
+- [x] 🔧 Fixable
+- [ ] 💭 Requires type information

packages/eslint-plugin/src/configs/all.ts

@@ -157,6 +157,8 @@ export = {
     '@typescript-eslint/space-before-function-paren': 'error',
     'space-infix-ops': 'off',
     '@typescript-eslint/space-infix-ops': 'error',
+    'space-before-blocks': 'off',
+    '@typescript-eslint/space-before-blocks': 'error',
     '@typescript-eslint/strict-boolean-expressions': 'error',
     '@typescript-eslint/switch-exhaustiveness-check': 'error',
     '@typescript-eslint/triple-slash-reference': 'error',

packages/eslint-plugin/src/rules/index.ts

@@ -112,6 +112,7 @@ import restrictTemplateExpressions from './restrict-template-expressions';
 import returnAwait from './return-await';
 import semi from './semi';
 import sortTypeUnionIntersectionMembers from './sort-type-union-intersection-members';
+import spaceBeforeBlocks from './space-before-blocks';
 import spaceBeforeFunctionParen from './space-before-function-paren';
 import spaceInfixOps from './space-infix-ops';
 import strictBooleanExpressions from './strict-boolean-expressions';
@@ -237,6 +238,7 @@ export default {
   'return-await': returnAwait,
   semi: semi,
   'sort-type-union-intersection-members': sortTypeUnionIntersectionMembers,
+  'space-before-blocks': spaceBeforeBlocks,
   'space-before-function-paren': spaceBeforeFunctionParen,
   'space-infix-ops': spaceInfixOps,
   'strict-boolean-expressions': strictBooleanExpressions,

packages/eslint-plugin/src/rules/space-before-blocks.ts

@@ -0,0 +1,90 @@
+import { TSESTree } from '@typescript-eslint/utils';
+import { getESLintCoreRule } from '../util/getESLintCoreRule';
+import * as util from '../util';
+
+const baseRule = getESLintCoreRule('space-before-blocks');
+
+export type Options = util.InferOptionsTypeFromRule<typeof baseRule>;
+export type MessageIds = util.InferMessageIdsTypeFromRule<typeof baseRule>;
+
+export default util.createRule<Options, MessageIds>({
+  name: 'space-before-blocks',
+  meta: {
+    type: 'layout',
+    docs: {
+      description: 'Enforces consistent spacing before blocks',
+      recommended: false,
+      extendsBaseRule: true,
+    },
+    fixable: baseRule.meta.fixable,
+    hasSuggestions: baseRule.meta.hasSuggestions,
+    schema: baseRule.meta.schema,
+    messages: {
+      // @ts-expect-error -- we report on this messageId so we need to ensure it's there in case ESLint changes in future
+      unexpectedSpace: 'Unexpected space before opening brace.',
+      // @ts-expect-error -- we report on this messageId so we need to ensure it's there in case ESLint changes in future
+      missingSpace: 'Missing space before opening brace.',
+      ...baseRule.meta.messages,
+    },
+  },
+  defaultOptions: ['always'],
+  create(context) {
+    const rules = baseRule.create(context);
+    const config = context.options[0];
+    const sourceCode = context.getSourceCode();
+
+    let requireSpace = true;
+
+    if (typeof config === 'object') {
+      requireSpace = config.classes === 'always';
+    } else if (config === 'never') {
+      requireSpace = false;
+    }
+
+    function checkPrecedingSpace(
+      node: TSESTree.Token | TSESTree.TSInterfaceBody,
+    ): void {
+      const precedingToken = sourceCode.getTokenBefore(node);
+      if (precedingToken && util.isTokenOnSameLine(precedingToken, node)) {
+        const hasSpace = sourceCode.isSpaceBetweenTokens(
+          precedingToken,
+          node as TSESTree.Token,
+        );
+
+        if (requireSpace && !hasSpace) {
+          context.report({
+            node,
+            messageId: 'missingSpace',
+            fix(fixer) {
+              return fixer.insertTextBefore(node, ' ');
+            },
+          });
+        } else if (!requireSpace && hasSpace) {
+          context.report({
+            node,
+            messageId: 'unexpectedSpace',
+            fix(fixer) {
+              return fixer.removeRange([
+                precedingToken.range[1],
+                node.range[0],
+              ]);
+            },
+          });
+        }
+      }
+    }
+
+    function checkSpaceAfterEnum(node: TSESTree.TSEnumDeclaration): void {
+      const punctuator = sourceCode.getTokenAfter(node.id);
+      if (punctuator) {
+        checkPrecedingSpace(punctuator);
+      }
+    }
+
+    return {
+      ...rules,
+      TSEnumDeclaration: checkSpaceAfterEnum,
+      TSInterfaceBody: checkPrecedingSpace,
+    };
+  },
+});

packages/eslint-plugin/src/util/getESLintCoreRule.ts

@@ -33,6 +33,7 @@ interface RuleMap {
   'prefer-const': typeof import('eslint/lib/rules/prefer-const');
   quotes: typeof import('eslint/lib/rules/quotes');
   semi: typeof import('eslint/lib/rules/semi');
+  'space-before-blocks': typeof import('eslint/lib/rules/space-before-blocks');
   'space-infix-ops': typeof import('eslint/lib/rules/space-infix-ops');
   strict: typeof import('eslint/lib/rules/strict');
 }