Attempt to retain input file line endings in codemod

packages/codemod-utils/src/transform/js.ts

@@ -57,6 +57,11 @@ export function transformJsFile(
   options: AstTransformOptions & Required<Pick<ParserOptions, 'sourceType'>>,
 ): AstTransformResult {
   const { applyDangerousEdits, fs, ...parserOptions } = options;
+  // Attempt to determine input file line endings, defaulting to the operating system default
+  const crlfLineEndings = source.includes('\r\n');
+  const lfLineEndings = !crlfLineEndings && source.includes('\n');
+  const lineTerminator = crlfLineEndings ? '\r\n' : lfLineEndings ? '\n' : undefined;
+  // Parse the source AST
   const ast = parse(source, {
     parser: {
       sourceFilename: parserOptions.sourceFilename,
@@ -70,6 +75,7 @@ export function transformJsFile(
       },
     },
   }) as ReturnType<typeof parseAst>;
+  // Transform the AST
   const uniqueErrors = new Map<string, SyntaxError>();
   const transformContext: AstTransformContext<AstCliContext> = {
     filename: parserOptions.sourceFilename,
@@ -83,8 +89,14 @@ export function transformJsFile(
     },
   };
   const transformedAst = transformAst(ast, transforms, transformContext, { source });
+  // If there were no modifications to the AST, return a null result
   if (!transformedAst && uniqueErrors.size === 0) return { source: null, errors: [] };
-  const transformedSource = transformedAst ? print(transformedAst).code : null;
+  // Print the transformed AST
+  const transformedSource = transformedAst
+    ? print(transformedAst, {
+        lineTerminator,
+      }).code
+    : null;
   return {
     source: transformedSource === source ? null : transformedSource,
     errors: Array.from(uniqueErrors.values()),

packages/codemods/src/versions/31.0.0/codemod.test.ts

@@ -0,0 +1,185 @@
+import { type CodemodFsUtils } from '@ag-grid-devtools/types';
+import { fs as memfs } from 'memfs';
+import { describe, expect, test } from 'vitest';
+
+import codemod from './codemod';
+
+describe('Retains line endings', () => {
+  describe('CRLF', () => {
+    describe('JavaScript source files', () => {
+      test('No modifications', () => {
+        const input = [
+          `import { Foo } from 'unrelated-package';`,
+          `new Foo(document.body, { bar: true });`,
+        ].join('\r\n');
+        const actual = codemod(
+          { path: './input.js', source: input },
+          {
+            applyDangerousEdits: true,
+            fs: createFsHelpers(memfs),
+          },
+        );
+        expect(actual).toEqual({ source: null, errors: [] });
+      });
+
+      test('Modifications', () => {
+        const input = [
+          `import { Grid } from 'ag-grid-community';`,
+          `const options = { foo: true };`,
+          `new Grid(document.body, options);`,
+        ].join('\r\n');
+        const expected = [
+          `import { createGrid } from 'ag-grid-community';`,
+          `const options = { foo: true };`,
+          `const optionsApi = createGrid(document.body, options);`,
+        ].join('\r\n');
+        const actual = codemod(
+          { path: './input.js', source: input },
+          {
+            applyDangerousEdits: true,
+            fs: createFsHelpers(memfs),
+          },
+        );
+        expect(actual).toEqual({ source: expected, errors: [] });
+      });
+    });
+
+    describe('Vue source files', () => {
+      test('No modifications', () => {
+        const input = [
+          `<script>`,
+          `export default {`,
+          `  data() {`,
+          `    return {`,
+          `      greeting: 'Hello World!'`,
+          `    }`,
+          `  }`,
+          `}`,
+          `</script>`,
+          ``,
+          `<template>`,
+          `  <p class="greeting">{{ greeting }}</p>`,
+          `<template>`,
+          ``,
+          `<style>`,
+          `.greeting {`,
+          `  color: red;`,
+          `  font-weight: bold;`,
+          `}`,
+          `</style>`,
+        ].join('\r\n');
+        const actual = codemod(
+          { path: './input.vue', source: input },
+          {
+            applyDangerousEdits: true,
+            fs: createFsHelpers(memfs),
+          },
+        );
+        expect(actual).toEqual({ source: null, errors: [] });
+      });
+
+      test('Modifications', () => {
+        const input = [
+          `<script>`,
+          `import { AgGridVue } from '@ag-grid-community/vue';`,
+          ``,
+          `export default {`,
+          `  components: {`,
+          `    'ag-grid-vue': AgGridVue,`,
+          `  },`,
+          `  data() {`,
+          `    return {`,
+          `      columnDefs: [],`,
+          `      rowData: [],`,
+          `      advancedFilterModel: {`,
+          `        filterType: 'join',`,
+          `        type: 'AND',`,
+          `        conditions: [],`,
+          `      },`,
+          `    };`,
+          `  },`,
+          `};`,
+          `</script>`,
+          ``,
+          `<template>`,
+          `  <div>`,
+          `    <ag-grid-vue`,
+          `      :columnDefs="columnDefs"`,
+          `      :rowData="rowData"`,
+          `      :advancedFilterModel="advancedFilterModel"`,
+          `    ></ag-grid-vue>`,
+          `  </div>`,
+          `</template>`,
+        ].join('\r\n');
+        const expected = [
+          `<script>`,
+          `import { AgGridVue } from '@ag-grid-community/vue';`,
+          ``,
+          `export default {`,
+          `  components: {`,
+          `    'ag-grid-vue': AgGridVue,`,
+          `  },`,
+          `  data() {`,
+          `    return {`,
+          `      columnDefs: [],`,
+          `      rowData: [],`,
+          `      advancedFilterModel: {`,
+          `        filter: {`,
+          `          advancedFilterModel: {`,
+          `            filterType: 'join',`,
+          `            type: 'AND',`,
+          `            conditions: []`,
+          `          }`,
+          `        }`,
+          `      },`,
+          `    };`,
+          `  },`,
+          `};`,
+          `</script>`,
+          ``,
+          `<template>`,
+          `  <div>`,
+          `    <ag-grid-vue`,
+          `      :columnDefs="columnDefs"`,
+          `      :rowData="rowData"`,
+          `      :initialState="advancedFilterModel"`,
+          `    ></ag-grid-vue>`,
+          `  </div>`,
+          `</template>`,
+        ].join('\r\n');
+        const actual = codemod(
+          { path: './input.vue', source: input },
+          {
+            applyDangerousEdits: true,
+            fs: createFsHelpers(memfs),
+          },
+        );
+        expect(actual).toEqual({
+          source: expected,
+          errors: [
+            new SyntaxError(
+              'Vue components are not yet fully supported via codemods and may require manual fixes',
+            ),
+          ],
+        });
+      });
+    });
+  });
+});
+
+function createFsHelpers(fs: typeof memfs): CodemodFsUtils {
+  return {
+    readFileSync,
+    writeFileSync,
+  };
+
+  function readFileSync(filename: string, encoding: 'utf-8'): string;
+  function readFileSync(filename: string, encoding: BufferEncoding): string | Buffer;
+  function readFileSync(filename: string, encoding: BufferEncoding): string | Buffer {
+    return fs.readFileSync(filename, encoding);
+  }
+
+  function writeFileSync(filename: string, data: string | Buffer): void {
+    return fs.writeFileSync(filename, data);
+  }
+}