feat: new if-newline rule

packages/basic/index.js

@@ -292,5 +292,6 @@ module.exports = {
 
     // antfu
     'antfu/no-leading-newline': 'error',
+    'antfu/if-newline': 'error',
   },
 }

packages/eslint-plugin-antfu/package.json

@@ -18,12 +18,14 @@
   "scripts": {
     "build": "rimraf dist && unbuild",
     "stub": "unbuild --stub",
+    "test": "vitest",
     "prepublishOnly": "nr build"
   },
   "dependencies": {
     "@typescript-eslint/utils": "^5.17.0"
   },
   "devDependencies": {
-    "unbuild": "^0.7.0"
+    "unbuild": "^0.7.0",
+    "vitest": "^0.8.2"
   }
 }

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

@@ -1,7 +1,9 @@
+import ifNewline from './rules/if-newline'
 import noLeadingNewline from './rules/no-leading-newline'
 
 export default {
   rules: {
     'no-leading-newline': noLeadingNewline,
+    'if-newline': ifNewline,
   },
 }

packages/eslint-plugin-antfu/src/rules/if-newline.test.ts

@@ -0,0 +1,30 @@
+import { RuleTester } from '@typescript-eslint/utils/dist/ts-eslint'
+import { it } from 'vitest'
+import rule, { RULE_NAME } from './if-newline'
+
+const valids = [
+  `if (true)
+  console.log('hello')
+`,
+  `if (true) {
+  console.log('hello')
+}`,
+]
+const invalids = [
+  ['if (true) console.log(\'hello\')', 'if (true) \nconsole.log(\'hello\')'],
+]
+
+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],
+      errors: [{ messageId: 'missingIfNewline' }],
+    })),
+  })
+})

packages/eslint-plugin-antfu/src/rules/if-newline.ts

@@ -0,0 +1,45 @@
+import { createEslintRule } from '../utils'
+
+export const RULE_NAME = 'if-newline'
+export type MessageIds = 'missingIfNewline'
+export type Options = []
+
+export default createEslintRule<Options, MessageIds>({
+  name: RULE_NAME,
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'Newline after if',
+      recommended: 'error',
+    },
+    fixable: 'code',
+    schema: [],
+    messages: {
+      missingIfNewline: 'Expect newline after if',
+    },
+  },
+  defaultOptions: [],
+  create: (context) => {
+    return {
+      IfStatement(node) {
+        if (!node.consequent)
+          return
+        if (node.consequent.type === 'BlockStatement')
+          return
+        if (node.test.loc.end.line === node.consequent.loc.start.line) {
+          context.report({
+            node,
+            loc: {
+              start: node.test.loc.end,
+              end: node.consequent.loc.start,
+            },
+            messageId: 'missingIfNewline',
+            fix(fixer) {
+              return fixer.replaceTextRange([node.consequent.range[0], node.consequent.range[0]], '\n')
+            },
+          })
+        }
+      },
+    }
+  },
+})

packages/eslint-plugin-antfu/src/rules/no-leading-newline.test.ts

@@ -0,0 +1,27 @@
+import { RuleTester } from '@typescript-eslint/utils/dist/ts-eslint'
+import { it } from 'vitest'
+import rule, { RULE_NAME } from './no-leading-newline'
+
+const valids = [
+  'import {} from \'foo\'',
+  `// comment
+import {} from ''`,
+]
+const invalids = [
+  '\n\nimport {} from \'fo\'',
+]
+
+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,
+      output: i.trim(),
+      errors: [{ messageId: 'noLeadingNewline' }],
+    })),
+  })
+})