From fb39eb9fc421e669d0a9a362ab36612086592cd2 Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Sun, 13 Feb 2022 21:26:10 +0100
Subject: [PATCH] cli: added lib utilities for working with git

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
---
 packages/cli/src/lib/git.test.ts | 54 +++++++++++++++++++++++++++++
 packages/cli/src/lib/git.ts      | 59 ++++++++++++++++++++++++++++++++
 2 files changed, 113 insertions(+)
 create mode 100644 packages/cli/src/lib/git.test.ts
 create mode 100644 packages/cli/src/lib/git.ts

diff --git a/packages/cli/src/lib/git.test.ts b/packages/cli/src/lib/git.test.ts
new file mode 100644
index 0000000000..ecb234f79a
--- /dev/null
+++ b/packages/cli/src/lib/git.test.ts
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2022 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { runGit, listChangedFiles } from './git';
+
+describe('runGit', () => {
+  it('runs a git command', async () => {
+    await expect(runGit('log', 'HEAD..HEAD')).resolves.toEqual(['']);
+  });
+
+  it('fails for unknown commands', async () => {
+    await expect(runGit('ryckbegäran')).rejects.toThrow(
+      /^git ryckbegäran failed, git: 'ryckbegäran' is not a git command/,
+    );
+  });
+
+  it('forwards failures', async () => {
+    await expect(
+      runGit(
+        'show',
+        '--quiet',
+        '--pretty=format:%s',
+        '0000000000000000000000000000000000000000',
+      ),
+    ).rejects.toThrow(
+      'git show failed, fatal: bad object 0000000000000000000000000000000000000000',
+    );
+  });
+});
+
+describe('listChangedFiles', () => {
+  it('requires a ref', async () => {
+    await expect(listChangedFiles('')).rejects.toThrow('ref is required');
+  });
+
+  it('should return something', async () => {
+    await expect(listChangedFiles('origin/master')).resolves.toEqual(
+      expect.any(Array),
+    );
+  });
+});
diff --git a/packages/cli/src/lib/git.ts b/packages/cli/src/lib/git.ts
new file mode 100644
index 0000000000..f8783804d1
--- /dev/null
+++ b/packages/cli/src/lib/git.ts
@@ -0,0 +1,59 @@
+/*
+ * Copyright 2022 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { assertError, ForwardedError } from '@backstage/errors';
+import { execFile as execFileCb } from 'child_process';
+import { promisify } from 'util';
+import { paths } from './paths';
+
+const execFile = promisify(execFileCb);
+
+/**
+ * Run a git command, trimming the output splitting it into lines.
+ */
+export async function runGit(...args: string[]) {
+  try {
+    const { stdout } = await execFile('git', args, {
+      shell: true,
+      cwd: paths.targetRoot,
+    });
+    return stdout.trim().split(/\r\n|\r|\n/);
+  } catch (error) {
+    assertError(error);
+    if (error.stderr || typeof error.code === 'number') {
+      const stderr = (error.stderr as undefined | Buffer)?.toString('utf8');
+      const msg = stderr?.trim() ?? `with exit code ${error.code}`;
+      throw new Error(`git ${args[0]} failed, ${msg}`);
+    }
+    throw new ForwardedError('Unknown execution error', error);
+  }
+}
+
+/**
+ * Returns a sorted list of all files that have changed since the merge base
+ * of the provided `ref` and HEAD, as well as all files that are not tracked by git.
+ */
+export async function listChangedFiles(ref: string) {
+  if (!ref) {
+    throw new Error('ref is required');
+  }
+  const [base] = await runGit('merge-base', 'HEAD', ref);
+
+  const tracked = await runGit('diff', '--name-only', base);
+  const untracked = await runGit('ls-files', '--others', '--exclude-standard');
+
+  return Array.from(new Set([...tracked, ...untracked]));
+}