Git support for --changedFilesWithAncestor (#5189)

* refactor of findChangedFiles

* make --changedFilesWithAncestor work with git

* fixup! refactor of findChangedFiles

* add withAncestor test to git

* docs: update changedFilesWithAncestor's description

* docs: add --changedFilesWithAncestor fix to changelog

* docs: updated docs for --changedFilesWithAncestor and --lastCommit

* docs: mention --watch in --changedFilesWithAncestor docs

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ### Fixes
 
+* `[jest-cli]` `jest --onlyChanged --changedFilesWithAncestor` now also works
+  with git. ([#5189](https://github.com/facebook/jest/pull/5189))
 * `[jest-config]` fix unexpected condition to avoid infinite recursion in
   Windows platform. ([#5161](https://github.com/facebook/jest/pull/5161))
 * `[jest-regex-util]` Fix breaking change in `--testPathPattern`

docs/CLI.md

@@ -102,6 +102,11 @@ two times slower._
 If you want to inspect the cache, use `--showConfig` and look at the
 `cacheDirectory` value. If you need to clear the cache, use `--clearCache`.
 
+### `--changedFilesWithAncestor`
+
+When used together with `--onlyChanged` or `--watch`, it runs tests related to
+the current changes and the changes made in the last commit.
+
 ### `--ci`
 
 When this option is provided, Jest will assume it is running in a CI
@@ -182,7 +187,8 @@ Write test results to a file when the `--json` option is also specified.
 
 ### `--lastCommit`
 
-Will run all tests affected by file changes in the last commit made.
+When used together with `--onlyChanged`, it will run all tests affected by file
+changes in the last commit made.
 
 ### `--listTests`
 

integration_tests/__tests__/jest_changed_files.test.js

@@ -175,6 +175,22 @@ test('gets changed files for git', async () => {
       .map(filePath => path.basename(filePath))
       .sort(),
   ).toEqual(['file1.txt']);
+
+  run(`${GIT} commit -am "test2"`, DIR);
+
+  writeFiles(DIR, {
+    'file4.txt': 'file4',
+  });
+
+  ({changedFiles: files} = await getChangedFilesForRoots(roots, {
+    withAncestor: true,
+  }));
+  // Returns files from current uncommitted state + the last commit
+  expect(
+    Array.from(files)
+      .map(filePath => path.basename(filePath))
+      .sort(),
+  ).toEqual(['file1.txt', 'file4.txt']);
 });
 
 test('gets changed files for hg', async () => {

packages/jest-changed-files/src/git.js

@@ -13,44 +13,59 @@ import type {Options, SCMAdapter} from 'types/ChangedFiles';
 import path from 'path';
 import childProcess from 'child_process';
 
+const findChangedFilesUsingCommand = async (args, cwd) => {
+  return new Promise((resolve, reject) => {
+    const child = childProcess.spawn('git', args, {cwd});
+    let stdout = '';
+    let stderr = '';
+    child.stdout.on('data', data => (stdout += data));
+    child.stderr.on('data', data => (stderr += data));
+    child.on('error', e => reject(e));
+    child.on('close', code => {
+      if (code === 0) {
+        stdout = stdout.trim();
+        if (stdout === '') {
+          resolve([]);
+        } else {
+          resolve(
+            stdout
+              .split('\n')
+              .map(changedPath => path.resolve(cwd, changedPath)),
+          );
+        }
+      } else {
+        reject(code + ': ' + stderr);
+      }
+    });
+  });
+};
+
 const adapter: SCMAdapter = {
   findChangedFiles: async (
     cwd: string,
     options?: Options,
   ): Promise<Array<Path>> => {
-    if (options && options.withAncestor) {
-      throw new Error(
-        '`changedFilesWithAncestor` is not supported in git repos.',
+    if (options && options.lastCommit) {
+      return await findChangedFilesUsingCommand(
+        ['show', '--name-only', '--pretty=%b', 'HEAD'],
+        cwd,
+      );
+    } else if (options && options.withAncestor) {
+      const changed = await findChangedFilesUsingCommand(
+        ['diff', '--name-only', 'HEAD^'],
+        cwd,
+      );
+      const untracked = await findChangedFilesUsingCommand(
+        ['ls-files', '--other', '--exclude-standard'],
+        cwd,
+      );
+      return changed.concat(untracked);
+    } else {
+      return await findChangedFilesUsingCommand(
+        ['ls-files', '--other', '--modified', '--exclude-standard'],
+        cwd,
       );
     }
-    return new Promise((resolve, reject) => {
-      const args =
-        options && options.lastCommit
-          ? ['show', '--name-only', '--pretty=%b', 'HEAD']
-          : ['ls-files', '--other', '--modified', '--exclude-standard'];
-      const child = childProcess.spawn('git', args, {cwd});
-      let stdout = '';
-      let stderr = '';
-      child.stdout.on('data', data => (stdout += data));
-      child.stderr.on('data', data => (stderr += data));
-      child.on('error', e => reject(e));
-      child.on('close', code => {
-        if (code === 0) {
-          stdout = stdout.trim();
-          if (stdout === '') {
-            resolve([]);
-          } else {
-            resolve(
-              stdout
-                .split('\n')
-                .map(changedPath => path.resolve(cwd, changedPath)),
-            );
-          }
-        } else {
-          reject(code + ': ' + stderr);
-        }
-      });
-    });
   },
 
   getRoot: async (cwd: string): Promise<?string> => {

packages/jest-cli/src/cli/args.js

@@ -104,9 +104,8 @@ export const options = {
   },
   changedFilesWithAncestor: {
     description:
-      'When used together with `--onlyChanged`, it runs tests ' +
-      'related to the current changes and the changes made in the last commit. ' +
-      '(NOTE: this only works for hg repos)',
+      'When used together with `--onlyChanged` or `--watch`, it runs tests ' +
+      'related to the current changes and the changes made in the last commit. ',
     type: 'boolean',
   },
   ci: {
@@ -268,8 +267,8 @@ export const options = {
   lastCommit: {
     default: undefined,
     description:
-      'Will run all tests affected by file changes in the last ' +
-      'commit made.',
+      'When used together with `--onlyChanged`, it will run all tests ' +
+      'affected by file changes in the last commit made.',
     type: 'boolean',
   },
   listTests: {