feat: Introduce --fixup to change subcommand

change/beachball-d725cdf6-20dd-41df-9402-cf9cf4f9bc08.json

@@ -0,0 +1,7 @@
+{
+  "type": "minor",
+  "comment": "feat: Introduce --fixup to change subcommand",
+  "packageName": "beachball",
+  "email": "evancharlton@microsoft.com",
+  "dependentChangeType": "patch"
+}

docs/cli/change.md

@@ -22,6 +22,7 @@ Some [general options](./options) including `--branch` and `--scope` also apply
 | ------------------------- | ----- | ------------------ | -------------------------------------------------------------------------- |
 | `--all`                   |       | false              | Generate change files for all packages                                     |
 | `--dependent-change-type` |       | `patch`            | use this change type for dependent packages                                |
+| `--fixup`                 |       | false              | Update the most recently added change file and create a fixup commit       |
 | `--message`               | `-m`  | (prompt)           | Description for all change files                                           |
 | `--no-commit`             |       | false              | Stage the change files rather than committing                              |
 | `--package`               |       | (changed packages) | Generate change files for these packages (can be specified multiple times) |
@@ -53,6 +54,12 @@ Generate change files for all packages, regardless of changes. This would most o
 beachball change --all --type patch --message 'update build output settings'
 ```
 
+Update the most recently added change file with additional changes and create a fixup commit. This is useful when you want to amend the most recent change file instead of creating a new one.
+
+```
+beachball change --fixup --type minor --message 'additional change'
+```
+
 ### Prompt walkthrough
 
 If you have changes that are not committed yet (i.e. `git status` reports changes), then `beachball change` will warn you about these:

src/__functional__/changefile/changeFixup.test.ts

@@ -0,0 +1,172 @@
+import { afterEach, beforeAll, beforeEach, describe, expect, it, jest } from '@jest/globals';
+import { change } from '../../commands/change';
+import { RepositoryFactory } from '../../__fixtures__/repositoryFactory';
+import { generateChangeFiles } from '../../__fixtures__/changeFiles';
+import { getDefaultOptions } from '../../options/getDefaultOptions';
+import type { ChangeFileInfo } from '../../types/ChangeInfo';
+import type { Repository } from '../../__fixtures__/repository';
+import type { BeachballOptions } from '../../types/BeachballOptions';
+import fs from 'fs-extra';
+import path from 'path';
+
+// Mock the promptForChange module to avoid interactive prompts
+jest.mock('../../changefile/promptForChange', () => ({
+  promptForChange: jest.fn(),
+}));
+
+import { promptForChange } from '../../changefile/promptForChange';
+const mockPromptForChange = promptForChange as jest.MockedFunction<typeof promptForChange>;
+
+describe('change command with fixup mode', () => {
+  let repositoryFactory: RepositoryFactory;
+  let repository: Repository;
+
+  function getOptions(options?: Partial<BeachballOptions>): BeachballOptions {
+    return {
+      ...getDefaultOptions(),
+      path: repository.rootPath,
+      ...options,
+    };
+  }
+
+  beforeAll(() => {
+    repositoryFactory = new RepositoryFactory('single');
+  });
+
+  beforeEach(() => {
+    repository = repositoryFactory.cloneRepository();
+    mockPromptForChange.mockReset();
+  });
+
+  afterEach(() => {
+    jest.restoreAllMocks();
+    repository?.cleanUp();
+  });
+
+  it('creates a normal change file when fixup is false', async () => {
+    const changes: ChangeFileInfo[] = [
+      {
+        type: 'patch',
+        comment: 'Test change',
+        packageName: 'foo',
+        email: 'test@example.com',
+        dependentChangeType: 'patch',
+      },
+    ];
+
+    mockPromptForChange.mockResolvedValue(changes);
+
+    const options = getOptions({
+      fixup: false,
+      package: ['foo'],
+      commit: false, // Disable commit for easier testing
+    });
+
+    await change(options);
+
+    // Verify a change file was created
+    const changeDir = path.join(repository.rootPath, 'change');
+    const changeFiles = fs.readdirSync(changeDir).filter(f => f.endsWith('.json'));
+    expect(changeFiles).toHaveLength(1);
+
+    // Verify the content
+    const changeFilePath = path.join(changeDir, changeFiles[0]);
+    const changeFileContent = fs.readJSONSync(changeFilePath);
+    expect(changeFileContent.comment).toBe('Test change');
+    expect(changeFileContent.type).toBe('patch');
+  });
+
+  it('updates existing change file and creates fixup commit when fixup is true', async () => {
+    // Create an initial change file
+    const initialChanges: ChangeFileInfo[] = [
+      {
+        type: 'patch',
+        comment: 'Initial change',
+        packageName: 'foo',
+        email: 'test@example.com',
+        dependentChangeType: 'patch',
+      },
+    ];
+
+    const options = getOptions({ commit: true }); // Enable commit to make sure change file is committed
+    generateChangeFiles(initialChanges, options);
+
+    // Now simulate a fixup operation
+    const fixupChanges: ChangeFileInfo[] = [
+      {
+        type: 'minor',
+        comment: 'Additional change',
+        packageName: 'foo',
+        email: 'test@example.com',
+        dependentChangeType: 'minor',
+      },
+    ];
+
+    mockPromptForChange.mockResolvedValue(fixupChanges);
+
+    const fixupOptions = getOptions({
+      fixup: true,
+      package: ['foo'],
+      commit: false, // We'll test the commit separately
+    });
+
+    await change(fixupOptions);
+
+    // Verify only one change file exists (the updated one)
+    const changeDir = path.join(repository.rootPath, 'change');
+    const changeFiles = fs.readdirSync(changeDir).filter(f => f.endsWith('.json'));
+    expect(changeFiles).toHaveLength(1);
+
+    // Verify the content was merged
+    const changeFilePath = path.join(changeDir, changeFiles[0]);
+    const changeFileContent = fs.readJSONSync(changeFilePath);
+    expect(changeFileContent.comment).toBe('Initial change\n\nAdditional change');
+    expect(changeFileContent.type).toBe('minor'); // Higher priority type
+  });
+
+  it('handles case when no existing change files exist in fixup mode', async () => {
+    const changes: ChangeFileInfo[] = [
+      {
+        type: 'patch',
+        comment: 'Test change',
+        packageName: 'foo',
+        email: 'test@example.com',
+        dependentChangeType: 'patch',
+      },
+    ];
+
+    mockPromptForChange.mockResolvedValue(changes);
+
+    const options = getOptions({
+      fixup: true,
+      package: ['foo'],
+      commit: false,
+    });
+
+    // Should not throw an error, but should fall back to creating a normal change file
+    await change(options);
+
+    // Verify a change file was created (fallback to normal behavior)
+    const changeDir = path.join(repository.rootPath, 'change');
+    const changeFiles = fs.existsSync(changeDir) ? fs.readdirSync(changeDir).filter(f => f.endsWith('.json')) : [];
+    expect(changeFiles).toHaveLength(1);
+
+    // Verify the content is correct
+    const changeFilePath = path.join(changeDir, changeFiles[0]);
+    const changeFileContent = fs.readJSONSync(changeFilePath);
+    expect(changeFileContent.comment).toBe('Test change');
+    expect(changeFileContent.type).toBe('patch');
+  });
+
+  it('handles empty changes gracefully', async () => {
+    mockPromptForChange.mockResolvedValue(undefined);
+
+    const options = getOptions({
+      fixup: true,
+      package: ['foo'],
+    });
+
+    // Should not throw an error
+    await change(options);
+  });
+});

src/__functional__/options/getCliOptions.test.ts

@@ -199,6 +199,16 @@ describe('getCliOptions', () => {
     expect(options).toEqual({ ...defaults, foo: ['bar', 'baz'] });
   });
 
+  it('parses fixup flag', () => {
+    const options = getCliOptionsTest(['change', '--fixup']);
+    expect(options).toEqual({ ...defaults, command: 'change', fixup: true });
+  });
+
+  it('parses negated fixup flag', () => {
+    const options = getCliOptionsTest(['change', '--no-fixup']);
+    expect(options).toEqual({ ...defaults, command: 'change', fixup: false });
+  });
+
   // documenting current behavior (doesn't have to stay this way)
   it('for additional options, does not handle multiple values as part of array', () => {
     // in this case the trailing value "baz" would be treated as the command since it's the first