feat: format for generics spacing

packages/eslint-plugin-antfu/package.json

@@ -19,6 +19,7 @@
     "@typescript-eslint/utils": "^5.36.1"
   },
   "devDependencies": {
+    "@types/node": "^18.11.8",
     "unbuild": "^0.8.10",
     "vitest": "^0.22.1"
   }

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

@@ -1,3 +1,4 @@
+import genericSpacing from './rules/generic-spacing'
 import ifNewline from './rules/if-newline'
 import importDedupe from './rules/import-dedupe'
 import preferInlineTypeImport from './rules/prefer-inline-type-import'
@@ -7,5 +8,6 @@ export default {
     'if-newline': ifNewline,
     'import-dedupe': importDedupe,
     'prefer-inline-type-import': preferInlineTypeImport,
+    'generic-spacing': genericSpacing,
   },
 }

packages/eslint-plugin-antfu/src/rules/generic-spacing.test.ts

@@ -0,0 +1,32 @@
+import { RuleTester } from '@typescript-eslint/utils/dist/ts-eslint'
+import { it } from 'vitest'
+import rule, { RULE_NAME } from './generic-spacing'
+
+const valids = [
+  'type Foo<T = true> = T',
+  `
+type Foo<
+  T = true,
+  K = false
+> = T`,
+]
+const invalids = [
+  ['type Foo<T=true> = T', 'type Foo<T = true> = T'],
+  ['type Foo<T,K> = T', 'type Foo<T, K> = T'],
+  ['type Foo<T=false,K=1|2> = T', 'type Foo<T = false, K = 1|2> = T', 3],
+] as const
+
+it('runs', () => {
+  const ruleTester: RuleTester = new RuleTester({
+    parser: require.resolve('@typescript-eslint/parser'),
+  })
+
+  ruleTester.run(RULE_NAME, rule, {
+    valid: valids,
+    invalid: invalids.map(i => ({
+      code: i[0],
+      output: i[1].trim(),
+      errors: Array.from({ length: i[2] || 1 }, () => ({ messageId: 'genericSpacingMismatch' })),
+    })),
+  })
+})

packages/eslint-plugin-antfu/src/rules/generic-spacing.ts

@@ -0,0 +1,69 @@
+import { createEslintRule } from '../utils'
+
+export const RULE_NAME = 'generic-spacing'
+export type MessageIds = 'genericSpacingMismatch'
+export type Options = []
+
+export default createEslintRule<Options, MessageIds>({
+  name: RULE_NAME,
+  meta: {
+    type: 'suggestion',
+    docs: {
+      description: 'Spaces around generic type parameters',
+      recommended: 'error',
+    },
+    fixable: 'code',
+    schema: [],
+    messages: {
+      genericSpacingMismatch: 'Generic spaces mismatch',
+    },
+  },
+  defaultOptions: [],
+  create: (context) => {
+    const sourceCode = context.getSourceCode()
+    return {
+      TSTypeParameterDeclaration: (node) => {
+        const params = node.params
+        for (let i = 1; i < params.length; i++) {
+          const prev = params[i - 1]
+          const current = params[i]
+          const from = prev.range[1]
+          const to = current.range[0]
+          const span = sourceCode.text.slice(from, to)
+          if (span !== ', ' && !span.match(/,\n/)) {
+            context.report({
+              *fix(fixer) {
+                yield fixer.replaceTextRange([from, to], ', ')
+              },
+              loc: {
+                start: prev.loc.end,
+                end: current.loc.start,
+              },
+              messageId: 'genericSpacingMismatch',
+              node,
+            })
+          }
+        }
+      },
+      TSTypeParameter: (node) => {
+        if (!node.default)
+          return
+        const from = node.name.range[1]
+        const to = node.default.range[0]
+        if (sourceCode.text.slice(from, to) !== ' = ') {
+          context.report({
+            *fix(fixer) {
+              yield fixer.replaceTextRange([from, to], ' = ')
+            },
+            loc: {
+              start: node.name.loc.end,
+              end: node.default.loc.start,
+            },
+            messageId: 'genericSpacingMismatch',
+            node,
+          })
+        }
+      },
+    }
+  },
+})

packages/typescript/index.js

@@ -106,6 +106,9 @@ module.exports = {
     'lines-between-class-members': 'off',
     '@typescript-eslint/lines-between-class-members': ['error', 'always', { exceptAfterSingleLine: true }],
 
+    // antfu
+    'antfu/generic-spacing': 'error',
+
     // The following rule overrides require a parser service, aka. require a `typescript.json` path.
     // This needs to be done individually for each project, and it slows down linting significantly.
     // 'no-throw-literal': 'off',