1 files changed, 117 insertions, 0 deletions
diff --git a/packages/core/src/utils/editor.test.ts b/packages/core/src/utils/editor.test.ts
new file mode 100644
index 00000000..74237c74
--- /dev/null
+++ b/packages/core/src/utils/editor.test.ts
@@ -0,0 +1,117 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { vi, describe, it, expect, beforeEach, type Mock } from 'vitest';
+import { checkHasEditor, getDiffCommand, openDiff } from './editor.js';
+import { execSync, spawn } from 'child_process';
+
+vi.mock('child_process', () => ({
+  execSync: vi.fn(),
+  spawn: vi.fn(),
+}));
+
+describe('checkHasEditor', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('should return true for vscode if "code" command exists', () => {
+    (execSync as Mock).mockReturnValue(Buffer.from('/usr/bin/code'));
+    expect(checkHasEditor('vscode')).toBe(true);
+    expect(execSync).toHaveBeenCalledWith('which code', { stdio: 'ignore' });
+  });
+
+  it('should return false for vscode if "code" command does not exist', () => {
+    (execSync as Mock).mockImplementation(() => {
+      throw new Error();
+    });
+    expect(checkHasEditor('vscode')).toBe(false);
+  });
+
+  it('should return true for vim if "vim" command exists', () => {
+    (execSync as Mock).mockReturnValue(Buffer.from('/usr/bin/vim'));
+    expect(checkHasEditor('vim')).toBe(true);
+    expect(execSync).toHaveBeenCalledWith('which vim', { stdio: 'ignore' });
+  });
+
+  it('should return false for vim if "vim" command does not exist', () => {
+    (execSync as Mock).mockImplementation(() => {
+      throw new Error();
+    });
+    expect(checkHasEditor('vim')).toBe(false);
+  });
+});
+
+describe('getDiffCommand', () => {
+  it('should return the correct command for vscode', () => {
+    const command = getDiffCommand('old.txt', 'new.txt', 'vscode');
+    expect(command).toEqual({
+      command: 'code',
+      args: ['--wait', '--diff', 'old.txt', 'new.txt'],
+    });
+  });
+
+  it('should return the correct command for vim', () => {
+    const command = getDiffCommand('old.txt', 'new.txt', 'vim');
+    expect(command?.command).toBe('vim');
+    expect(command?.args).toContain('old.txt');
+    expect(command?.args).toContain('new.txt');
+  });
+
+  it('should return null for an unsupported editor', () => {
+    // @ts-expect-error Testing unsupported editor
+    const command = getDiffCommand('old.txt', 'new.txt', 'nano');
+    expect(command).toBeNull();
+  });
+});
+
+describe('openDiff', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('should call spawn for vscode', async () => {
+    const mockSpawn = {
+      on: vi.fn((event, cb) => {
+        if (event === 'close') {
+          cb(0);
+        }
+      }),
+    };
+    (spawn as Mock).mockReturnValue(mockSpawn);
+    await openDiff('old.txt', 'new.txt', 'vscode');
+    expect(spawn).toHaveBeenCalledWith(
+      'code',
+      ['--wait', '--diff', 'old.txt', 'new.txt'],
+      { stdio: 'inherit' },
+    );
+    expect(mockSpawn.on).toHaveBeenCalledWith('close', expect.any(Function));
+    expect(mockSpawn.on).toHaveBeenCalledWith('error', expect.any(Function));
+  });
+
+  it('should call execSync for vim', async () => {
+    await openDiff('old.txt', 'new.txt', 'vim');
+    expect(execSync).toHaveBeenCalled();
+    const command = (execSync as Mock).mock.calls[0][0];
+    expect(command).toContain('vim');
+    expect(command).toContain('old.txt');
+    expect(command).toContain('new.txt');
+  });
+
+  it('should handle spawn error for vscode', async () => {
+    const mockSpawn = {
+      on: vi.fn((event, cb) => {
+        if (event === 'error') {
+          cb(new Error('spawn error'));
+        }
+      }),
+    };
+    (spawn as Mock).mockReturnValue(mockSpawn);
+    await expect(openDiff('old.txt', 'new.txt', 'vscode')).rejects.toThrow(
+      'spawn error',
+    );
+  });
+});