[trd:trd-2026-004-vcs-backend-abstraction:phase:D] Phase D: JujutsuBackend Implementation (v0.3-alpha) (bd-ia7z)

src/lib/vcs/__tests__/factory.test.ts

@@ -0,0 +1,199 @@
+/**
+ * TRD-003-TEST: VcsBackendFactory verification.
+ *
+ * Tests:
+ * 1. Explicit 'git' backend selection → returns GitBackend
+ * 2. Explicit 'jujutsu' backend selection → returns JujutsuBackend
+ * 3. Auto-detection with .git/ → returns GitBackend
+ * 4. Auto-detection with .jj/ → returns JujutsuBackend
+ * 5. Auto-detection with both .jj/ and .git/ → JujutsuBackend wins
+ * 6. Auto-detection with neither → throws descriptive error
+ *
+ * Tests use temporary directories (no actual git/jj CLI calls needed for factory logic).
+ */
+
+import { describe, it, expect, afterEach } from 'vitest';
+import {
+  mkdtempSync,
+  mkdirSync,
+  rmSync,
+  realpathSync,
+} from 'node:fs';
+import { join } from 'node:path';
+import { tmpdir } from 'node:os';
+import { VcsBackendFactory, GitBackend, JujutsuBackend } from '../index.js';
+import type { VcsConfig } from '../types.js';
+
+// ── Helpers ──────────────────────────────────────────────────────────────────
+
+const tempDirs: string[] = [];
+
+function makeTempDir(): string {
+  const dir = realpathSync(mkdtempSync(join(tmpdir(), 'foreman-factory-test-')));
+  tempDirs.push(dir);
+  return dir;
+}
+
+function makeDirWithGit(): string {
+  const dir = makeTempDir();
+  mkdirSync(join(dir, '.git'));
+  return dir;
+}
+
+function makeDirWithJj(): string {
+  const dir = makeTempDir();
+  mkdirSync(join(dir, '.jj'));
+  return dir;
+}
+
+function makeDirWithBoth(): string {
+  const dir = makeTempDir();
+  mkdirSync(join(dir, '.git'));
+  mkdirSync(join(dir, '.jj'));
+  return dir;
+}
+
+afterEach(() => {
+  for (const dir of tempDirs) {
+    rmSync(dir, { recursive: true, force: true });
+  }
+  tempDirs.length = 0;
+});
+
+// ── Explicit backend selection ────────────────────────────────────────────────
+
+describe('VcsBackendFactory.create — explicit backend selection', () => {
+  it('returns GitBackend when backend is "git"', async () => {
+    const dir = makeTempDir();
+    const config: VcsConfig = { backend: 'git' };
+    const backend = await VcsBackendFactory.create(config, dir);
+    expect(backend).toBeInstanceOf(GitBackend);
+  });
+
+  it('returns JujutsuBackend when backend is "jujutsu"', async () => {
+    const dir = makeTempDir();
+    const config: VcsConfig = { backend: 'jujutsu' };
+    const backend = await VcsBackendFactory.create(config, dir);
+    expect(backend).toBeInstanceOf(JujutsuBackend);
+  });
+
+  it('passes the projectPath to GitBackend constructor', async () => {
+    const dir = makeTempDir();
+    const config: VcsConfig = { backend: 'git' };
+    const backend = await VcsBackendFactory.create(config, dir) as GitBackend;
+    expect(backend.projectPath).toBe(dir);
+  });
+
+  it('passes the projectPath to JujutsuBackend constructor', async () => {
+    const dir = makeTempDir();
+    const config: VcsConfig = { backend: 'jujutsu' };
+    const backend = await VcsBackendFactory.create(config, dir) as JujutsuBackend;
+    expect(backend.projectPath).toBe(dir);
+  });
+
+  it('explicit git backend ignores absence of .git directory', async () => {
+    // Factory must NOT do filesystem detection for explicit backends
+    const dir = makeTempDir(); // no .git or .jj
+    const config: VcsConfig = { backend: 'git' };
+    const backend = await VcsBackendFactory.create(config, dir);
+    expect(backend).toBeInstanceOf(GitBackend);
+  });
+
+  it('explicit jujutsu backend ignores absence of .jj directory', async () => {
+    const dir = makeTempDir(); // no .git or .jj
+    const config: VcsConfig = { backend: 'jujutsu' };
+    const backend = await VcsBackendFactory.create(config, dir);
+    expect(backend).toBeInstanceOf(JujutsuBackend);
+  });
+});
+
+// ── Auto-detection ────────────────────────────────────────────────────────────
+
+describe('VcsBackendFactory.create — auto-detection', () => {
+  it('detects GitBackend when only .git/ exists', async () => {
+    const dir = makeDirWithGit();
+    const config: VcsConfig = { backend: 'auto' };
+    const backend = await VcsBackendFactory.create(config, dir);
+    expect(backend).toBeInstanceOf(GitBackend);
+  });
+
+  it('detects JujutsuBackend when only .jj/ exists', async () => {
+    const dir = makeDirWithJj();
+    const config: VcsConfig = { backend: 'auto' };
+    const backend = await VcsBackendFactory.create(config, dir);
+    expect(backend).toBeInstanceOf(JujutsuBackend);
+  });
+
+  it('.jj/ takes precedence over .git/ in colocated repos', async () => {
+    const dir = makeDirWithBoth(); // has both .git/ and .jj/
+    const config: VcsConfig = { backend: 'auto' };
+    const backend = await VcsBackendFactory.create(config, dir);
+    expect(backend).toBeInstanceOf(JujutsuBackend);
+  });
+
+  it('throws descriptive error when neither .git/ nor .jj/ exists', async () => {
+    const dir = makeTempDir(); // no .git or .jj
+    const config: VcsConfig = { backend: 'auto' };
+    await expect(VcsBackendFactory.create(config, dir)).rejects.toThrow(
+      /No VCS detected/,
+    );
+  });
+
+  it('error message includes the project path for debugging', async () => {
+    const dir = makeTempDir();
+    const config: VcsConfig = { backend: 'auto' };
+    await expect(VcsBackendFactory.create(config, dir)).rejects.toThrow(dir);
+  });
+
+  it('error message mentions both expected directory names', async () => {
+    const dir = makeTempDir();
+    const config: VcsConfig = { backend: 'auto' };
+    await expect(VcsBackendFactory.create(config, dir)).rejects.toThrow(
+      /\.git.*\.jj|\.jj.*\.git/,
+    );
+  });
+});
+
+// ── Config sub-options pass-through ──────────────────────────────────────────
+
+describe('VcsBackendFactory.create — VcsConfig sub-options', () => {
+  it('accepts git sub-config without error', async () => {
+    const dir = makeTempDir();
+    const config: VcsConfig = { backend: 'git', git: { useTown: true } };
+    const backend = await VcsBackendFactory.create(config, dir);
+    expect(backend).toBeInstanceOf(GitBackend);
+  });
+
+  it('accepts jujutsu sub-config without error', async () => {
+    const dir = makeTempDir();
+    const config: VcsConfig = { backend: 'jujutsu', jujutsu: { minVersion: '0.25.0' } };
+    const backend = await VcsBackendFactory.create(config, dir);
+    expect(backend).toBeInstanceOf(JujutsuBackend);
+  });
+
+  it('accepts auto with both sub-configs and detects by filesystem', async () => {
+    const dir = makeDirWithGit();
+    const config: VcsConfig = {
+      backend: 'auto',
+      git: { useTown: false },
+      jujutsu: { minVersion: '0.25.0' },
+    };
+    const backend = await VcsBackendFactory.create(config, dir);
+    expect(backend).toBeInstanceOf(GitBackend);
+  });
+});
+
+// ── Return type ───────────────────────────────────────────────────────────────
+
+describe('VcsBackendFactory.create — return type', () => {
+  it('returns a value assignable to VcsBackend (structural typing)', async () => {
+    const dir = makeTempDir();
+    const config: VcsConfig = { backend: 'git' };
+    const backend = await VcsBackendFactory.create(config, dir);
+    // Check that all interface methods exist on the returned object
+    expect(typeof backend.getRepoRoot).toBe('function');
+    expect(typeof backend.createWorkspace).toBe('function');
+    expect(typeof backend.merge).toBe('function');
+    expect(typeof backend.getFinalizeCommands).toBe('function');
+  });
+});