feat: add --check CLI option

README.md

@@ -101,6 +101,10 @@ Outputs the name of each file right before it is proccessed. This can be useful
 
 Prevent `git commit` if any files are fixed.
 
+### `--check`
+
+Check that files are correctly formatted, but don't format them. This is useful on CI to verify that all changed files in the current branch were correctly formatted.
+
 <!-- Undocumented = Unsupported :D
 
 ### `--config`

bin/pretty-quick.js

@@ -32,8 +32,12 @@ const prettyQuickResult = prettyQuick(
       console.log(`✗ Found ${chalk.bold('partially')} staged file ${file}.`);
     },
 
-    onWriteFile: file => {
-      console.log(`✍️  Fixing up ${chalk.bold(file)}.`);
+    onProcessFile: file => {
+      if (args.check) {
+        console.log(`👀  Checking ${chalk.bold(file)}.`);
+      } else {
+        console.log(`✍️  Fixing up ${chalk.bold(file)}.`);
+      }
     },
 
     onExamineFile: file => {
@@ -56,5 +60,10 @@ if (prettyQuickResult.success) {
       '✗ File had to be prettified and prettyQuick was set to bail mode.'
     );
   }
+  if (prettyQuickResult.errors.indexOf('CHECK_FAILED') !== -1) {
+    console.log(
+      '✗ Code style issues found in the above file(s). Forgot to run Prettier?'
+    );
+  }
   process.exit(1); // ensure git hooks abort
 }

src/__tests__/scm-git.test.js

@@ -150,63 +150,63 @@ describe('with git', () => {
     expect(onFoundChangedFiles).toHaveBeenCalledWith(['./foo.js', './bar.md']);
   });
 
-  test('calls onWriteFile with changed files', () => {
-    const onWriteFile = jest.fn();
+  test('calls onProcessFile with changed files', () => {
+    const onProcessFile = jest.fn();
     mockGitFs();
 
-    prettyQuick('root', { since: 'banana', onWriteFile });
+    prettyQuick('root', { since: 'banana', onProcessFile });
 
-    expect(onWriteFile).toHaveBeenCalledWith('./foo.js');
-    expect(onWriteFile).toHaveBeenCalledWith('./bar.md');
-    expect(onWriteFile.mock.calls.length).toBe(2);
+    expect(onProcessFile).toHaveBeenCalledWith('./foo.js');
+    expect(onProcessFile).toHaveBeenCalledWith('./bar.md');
+    expect(onProcessFile.mock.calls.length).toBe(2);
   });
 
-  test('calls onWriteFile with changed files for the given pattern', () => {
-    const onWriteFile = jest.fn();
+  test('calls onProcessFile with changed files for the given pattern', () => {
+    const onProcessFile = jest.fn();
     mockGitFs();
-    prettyQuick('root', { pattern: '*.md', since: 'banana', onWriteFile });
-    expect(onWriteFile.mock.calls).toEqual([['./bar.md']]);
+    prettyQuick('root', { pattern: '*.md', since: 'banana', onProcessFile });
+    expect(onProcessFile.mock.calls).toEqual([['./bar.md']]);
   });
 
-  test('calls onWriteFile with changed files for the given globstar pattern', () => {
-    const onWriteFile = jest.fn();
+  test('calls onProcessFile with changed files for the given globstar pattern', () => {
+    const onProcessFile = jest.fn();
     mockGitFs();
     prettyQuick('root', {
       pattern: '**/*.md',
       since: 'banana',
-      onWriteFile,
+      onProcessFile,
     });
-    expect(onWriteFile.mock.calls).toEqual([['./bar.md']]);
+    expect(onProcessFile.mock.calls).toEqual([['./bar.md']]);
   });
 
-  test('calls onWriteFile with changed files for the given extglob pattern', () => {
-    const onWriteFile = jest.fn();
+  test('calls onProcessFile with changed files for the given extglob pattern', () => {
+    const onProcessFile = jest.fn();
     mockGitFs();
     prettyQuick('root', {
       pattern: '*.*(md|foo|bar)',
       since: 'banana',
-      onWriteFile,
+      onProcessFile,
     });
-    expect(onWriteFile.mock.calls).toEqual([['./bar.md']]);
+    expect(onProcessFile.mock.calls).toEqual([['./bar.md']]);
   });
 
-  test('calls onWriteFile with changed files for an array of globstar patterns', () => {
-    const onWriteFile = jest.fn();
+  test('calls onProcessFile with changed files for an array of globstar patterns', () => {
+    const onProcessFile = jest.fn();
     mockGitFs();
     prettyQuick('root', {
       pattern: ['**/*.foo', '**/*.md', '**/*.bar'],
       since: 'banana',
-      onWriteFile,
+      onProcessFile,
     });
-    expect(onWriteFile.mock.calls).toEqual([['./bar.md']]);
+    expect(onProcessFile.mock.calls).toEqual([['./bar.md']]);
   });
 
   test('writes formatted files to disk', () => {
-    const onWriteFile = jest.fn();
+    const onProcessFile = jest.fn();
 
     mockGitFs();
 
-    prettyQuick('root', { since: 'banana', onWriteFile });
+    prettyQuick('root', { since: 'banana', onProcessFile });
 
     expect(fs.readFileSync('/foo.js', 'utf8')).toEqual('formatted:foo()');
     expect(fs.readFileSync('/bar.md', 'utf8')).toEqual('formatted:# foo');
@@ -316,20 +316,20 @@ describe('with git', () => {
   });
 
   test('ignore files matching patterns from the repositories root .prettierignore', () => {
-    const onWriteFile = jest.fn();
+    const onProcessFile = jest.fn();
     mockGitFs('', {
       '/.prettierignore': '*.md',
     });
-    prettyQuick('/sub-directory/', { since: 'banana', onWriteFile });
-    expect(onWriteFile.mock.calls).toEqual([['./foo.js']]);
+    prettyQuick('/sub-directory/', { since: 'banana', onProcessFile });
+    expect(onProcessFile.mock.calls).toEqual([['./foo.js']]);
   });
 
   test('ignore files matching patterns from the working directories .prettierignore', () => {
-    const onWriteFile = jest.fn();
+    const onProcessFile = jest.fn();
     mockGitFs('', {
       '/sub-directory/.prettierignore': '*.md',
     });
-    prettyQuick('/sub-directory/', { since: 'banana', onWriteFile });
-    expect(onWriteFile.mock.calls).toEqual([['./foo.js']]);
+    prettyQuick('/sub-directory/', { since: 'banana', onProcessFile });
+    expect(onProcessFile.mock.calls).toEqual([['./foo.js']]);
   });
 });

src/__tests__/scm-hg.test.js

@@ -106,51 +106,51 @@ describe('with hg', () => {
     expect(onFoundChangedFiles).toHaveBeenCalledWith(['./foo.js', './bar.md']);
   });
 
-  test('calls onWriteFile with changed files', () => {
-    const onWriteFile = jest.fn();
+  test('calls onProcessFile with changed files', () => {
+    const onProcessFile = jest.fn();
     mockHgFs();
 
-    prettyQuick('root', { since: 'banana', onWriteFile });
+    prettyQuick('root', { since: 'banana', onProcessFile });
 
-    expect(onWriteFile).toHaveBeenCalledWith('./foo.js');
-    expect(onWriteFile).toHaveBeenCalledWith('./bar.md');
+    expect(onProcessFile).toHaveBeenCalledWith('./foo.js');
+    expect(onProcessFile).toHaveBeenCalledWith('./bar.md');
   });
 
-  test('calls onWriteFile with changed files for the given pattern', () => {
-    const onWriteFile = jest.fn();
+  test('calls onProcessFile with changed files for the given pattern', () => {
+    const onProcessFile = jest.fn();
     mockHgFs();
-    prettyQuick('root', { pattern: '*.md', since: 'banana', onWriteFile });
-    expect(onWriteFile.mock.calls).toEqual([['./bar.md']]);
+    prettyQuick('root', { pattern: '*.md', since: 'banana', onProcessFile });
+    expect(onProcessFile.mock.calls).toEqual([['./bar.md']]);
   });
 
-  test('calls onWriteFile with changed files for the given globstar pattern', () => {
-    const onWriteFile = jest.fn();
+  test('calls onProcessFile with changed files for the given globstar pattern', () => {
+    const onProcessFile = jest.fn();
     mockHgFs();
     prettyQuick('root', {
       pattern: '**/*.md',
       since: 'banana',
-      onWriteFile,
+      onProcessFile,
     });
-    expect(onWriteFile.mock.calls).toEqual([['./bar.md']]);
+    expect(onProcessFile.mock.calls).toEqual([['./bar.md']]);
   });
 
-  test('calls onWriteFile with changed files for the given extglob pattern', () => {
-    const onWriteFile = jest.fn();
+  test('calls onProcessFile with changed files for the given extglob pattern', () => {
+    const onProcessFile = jest.fn();
     mockHgFs();
     prettyQuick('root', {
       pattern: '*.*(md|foo|bar)',
       since: 'banana',
-      onWriteFile,
+      onProcessFile,
     });
-    expect(onWriteFile.mock.calls).toEqual([['./bar.md']]);
+    expect(onProcessFile.mock.calls).toEqual([['./bar.md']]);
   });
 
   test('writes formatted files to disk', () => {
-    const onWriteFile = jest.fn();
+    const onProcessFile = jest.fn();
 
     mockHgFs();
 
-    prettyQuick('root', { since: 'banana', onWriteFile });
+    prettyQuick('root', { since: 'banana', onProcessFile });
 
     expect(fs.readFileSync('/foo.js', 'utf8')).toEqual('formatted:foo()');
     expect(fs.readFileSync('/bar.md', 'utf8')).toEqual('formatted:# foo');
@@ -172,15 +172,15 @@ describe('with hg', () => {
     expect(result).toEqual({ errors: ['BAIL_ON_WRITE'], success: false });
   });
 
-  test('calls onWriteFile with changed files for an array of globstar patterns', () => {
-    const onWriteFile = jest.fn();
+  test('calls onProcessFile with changed files for an array of globstar patterns', () => {
+    const onProcessFile = jest.fn();
     mockHgFs();
     prettyQuick('root', {
       pattern: ['**/*.foo', '**/*.md', '**/*.bar'],
       since: 'banana',
-      onWriteFile,
+      onProcessFile,
     });
-    expect(onWriteFile.mock.calls).toEqual([['./bar.md']]);
+    expect(onProcessFile.mock.calls).toEqual([['./bar.md']]);
   });
 
   test('without --staged does NOT stage changed files', () => {
@@ -215,20 +215,20 @@ describe('with hg', () => {
   });
 
   test('ignore files matching patterns from the repositories root .prettierignore', () => {
-    const onWriteFile = jest.fn();
+    const onProcessFile = jest.fn();
     mockHgFs({
       '/.prettierignore': '*.md',
     });
-    prettyQuick('/sub-directory/', { since: 'banana', onWriteFile });
-    expect(onWriteFile.mock.calls).toEqual([['./foo.js']]);
+    prettyQuick('/sub-directory/', { since: 'banana', onProcessFile });
+    expect(onProcessFile.mock.calls).toEqual([['./foo.js']]);
   });
 
   test('ignore files matching patterns from the working directories .prettierignore', () => {
-    const onWriteFile = jest.fn();
+    const onProcessFile = jest.fn();
     mockHgFs({
       '/sub-directory/.prettierignore': '*.md',
     });
-    prettyQuick('/sub-directory/', { since: 'banana', onWriteFile });
-    expect(onWriteFile.mock.calls).toEqual([['./foo.js']]);
+    prettyQuick('/sub-directory/', { since: 'banana', onProcessFile });
+    expect(onProcessFile.mock.calls).toEqual([['./foo.js']]);
   });
 });

src/index.js

@@ -1,5 +1,5 @@
 import scms from './scms';
-import formatFiles from './formatFiles';
+import processFiles from './processFiles';
 import createIgnorer from './createIgnorer';
 import createMatcher from './createMatcher';
 import isSupportedExtension from './isSupportedExtension';
@@ -14,11 +14,12 @@ export default (
     restage = true,
     branch,
     bail,
+    check,
     verbose,
     onFoundSinceRevision,
     onFoundChangedFiles,
     onPartiallyStagedFile,
-    onWriteFile,
+    onProcessFile,
     onExamineFile,
   } = {}
 ) => {
@@ -60,10 +61,15 @@ export default (
 
   const failReasons = new Set();
 
-  formatFiles(directory, changedFiles, {
+  processFiles(directory, changedFiles, {
+    check,
     config,
-    onWriteFile: file => {
-      onWriteFile && onWriteFile(file);
+    onProcessFile: file => {
+      onProcessFile && onProcessFile(file);
+      if (check) {
+        failReasons.add('CHECK_FAILED');
+        return;
+      }
       if (bail) {
         failReasons.add('BAIL_ON_WRITE');
       }

src/processFiles.js

@@ -0,0 +1,35 @@
+import { readFileSync, writeFileSync } from 'fs';
+import * as prettier from 'prettier';
+import { join } from 'path';
+
+export default (
+  directory,
+  files,
+  { check, config, onProcessFile, onExamineFile } = {}
+) => {
+  for (const relative of files) {
+    onExamineFile && onExamineFile(relative);
+    const file = join(directory, relative);
+    const options = Object.assign(
+      {},
+      prettier.resolveConfig.sync(file, {
+        config,
+        editorconfig: true,
+      }),
+      { filepath: file }
+    );
+    const input = readFileSync(file, 'utf8');
+
+    if (check && !prettier.check(input, options)) {
+      onProcessFile && onProcessFile(relative);
+      return;
+    }
+
+    const output = prettier.format(input, options);
+
+    if (output !== input) {
+      writeFileSync(file, output);
+      onProcessFile && onProcessFile(relative);
+    }
+  }
+};