fix: conversion of LF to CRLF

transforms/magic-redirect.ts

@@ -10,6 +10,7 @@ import {
   memberExpression,
 } from 'jscodeshift'
 import { getParsedFile } from '../utils/parse'
+import { getOptions } from '../utils/recastOptions'
 import { recursiveParent } from '../utils/recursiveParent'
 
 const unifiedMagicString = (path: ASTPath<CallExpression>, projectRequestName: string) => {
@@ -51,5 +52,5 @@ export default function transformer(file: FileInfo, _api: API) {
     })
     .map((path) => unifiedMagicString(path, recursiveParent(path.parentPath) || 'req'))
 
-  return parsedFile.toSource()
+  return parsedFile.toSource(getOptions(file.source))
 }

transforms/pluralized-methods.ts

@@ -1,6 +1,7 @@
 import type { API, FileInfo } from 'jscodeshift'
 import { Identifier, identifier } from 'jscodeshift'
 import { getParsedFile } from '../utils/parse'
+import { getOptions } from '../utils/recastOptions'
 
 export default function transformer(file: FileInfo, _api: API): string {
   const parsedFile = getParsedFile(file)
@@ -17,5 +18,5 @@ export default function transformer(file: FileInfo, _api: API): string {
       .replaceWith(() => identifier(plural))
   }
 
-  return parsedFile.toSource()
+  return parsedFile.toSource(getOptions(file.source))
 }

transforms/req-param.ts

@@ -1,5 +1,6 @@
 import type { API, FileInfo } from 'jscodeshift'
 import { CallExpression, identifier, memberExpression, withParser } from 'jscodeshift'
+import { getOptions } from '../utils/recastOptions'
 import { recursiveParent } from '../utils/recursiveParent'
 
 export default function transformer(file: FileInfo, _api: API): string {
@@ -40,5 +41,5 @@ export default function transformer(file: FileInfo, _api: API): string {
 
       return path
     })
-    .toSource()
+    .toSource(getOptions(file.source))
 }

transforms/v4-deprecated-signatures.ts

@@ -1,5 +1,6 @@
 import type { API, ASTPath, FileInfo } from 'jscodeshift'
 import { CallExpression, callExpression, identifier, memberExpression, withParser } from 'jscodeshift'
+import { getOptions } from '../utils/recastOptions'
 import { recursiveParent } from '../utils/recursiveParent'
 
 const separateStatusAndBody = (path: ASTPath<CallExpression>, calleePropertyName: string) => {
@@ -153,5 +154,5 @@ export default function transformer(file: FileInfo, _api: API): string {
       return path
     })
 
-  return parsedFile.toSource()
+  return parsedFile.toSource(getOptions(file.source))
 }

utils/__test__/recastOptions.spec.ts

@@ -0,0 +1,68 @@
+import { getOptions } from '../recastOptions'
+
+describe('recastOptions', () => {
+  describe('getOptions', () => {
+    it('should return Unix line terminator for code with only LF', () => {
+      const code = 'const a = 1\nconst b = 2\n'
+      const result = getOptions(code)
+
+      expect(result).toEqual({ lineTerminator: '\n' })
+    })
+
+    it('should return Windows line terminator for code with only CRLF', () => {
+      const code = 'const a = 1\r\nconst b = 2\r\n'
+      const result = getOptions(code)
+
+      expect(result).toEqual({ lineTerminator: '\r\n' })
+    })
+
+    it('should return Unix line terminator for code with mixed line terminators', () => {
+      const code = 'const a = 1\r\nconst b = 2\nconst c = 3\r\n'
+      const result = getOptions(code)
+
+      expect(result).toEqual({ lineTerminator: '\n' })
+    })
+
+    it('should return Unix line terminator for code with no line terminators', () => {
+      const code = 'const a = 1'
+      const result = getOptions(code)
+
+      expect(result).toEqual({ lineTerminator: '\n' })
+    })
+
+    it('should return Unix line terminator for empty string', () => {
+      const code = ''
+      const result = getOptions(code)
+
+      expect(result).toEqual({ lineTerminator: '\n' })
+    })
+
+    it('should handle code with LF at beginning after CR', () => {
+      const code = '\r\nconst a = 1\nconst b = 2'
+      const result = getOptions(code)
+
+      expect(result).toEqual({ lineTerminator: '\n' })
+    })
+
+    it('should handle single CRLF without other line breaks', () => {
+      const code = 'const a = 1\r\nconst b = 2'
+      const result = getOptions(code)
+
+      expect(result).toEqual({ lineTerminator: '\r\n' })
+    })
+
+    it('should handle multiple CRLF without LF', () => {
+      const code = 'line1\r\nline2\r\nline3\r\n'
+      const result = getOptions(code)
+
+      expect(result).toEqual({ lineTerminator: '\r\n' })
+    })
+
+    it('should detect LF even when preceded by CR in different context', () => {
+      const code = 'const str = "\\r"\nconst a = 1\r\n'
+      const result = getOptions(code)
+
+      expect(result).toEqual({ lineTerminator: '\n' })
+    })
+  })
+})

utils/recastOptions.ts

@@ -0,0 +1,17 @@
+/**
+ * By default, jscodeshift(recast) uses the line terminator of the OS the code runs on.
+ * This is often not desired, so we instead try to detect it from the input.
+ * If there is at least one Windows-style linebreak (CRLF) in the input and
+ * no Unix-style linebreak (LF), use that. In all other cases, use Unix-style (LF).
+ * @return '\n' or '\r\n'
+ */
+export function getOptions(code: string) {
+  return { lineTerminator: detectLineTerminator(code) }
+}
+
+function detectLineTerminator(code: string) {
+  const hasCRLF = /\r\n/.test(code)
+  const hasLF = /[^\r]\n/.test(code)
+
+  return hasCRLF && !hasLF ? '\r\n' : '\n'
+}