diff --git a/.tests/test_cli.py b/.tests/test_cli.py
new file mode 100644
index 0000000..dd75d20
--- /dev/null
+++ b/.tests/test_cli.py
@@ -0,0 +1,111 @@
+"""Tests for the CLI module."""
+
+import tempfile
+import yaml
+from click.testing import CliRunner
+
+from openapi_mock.cli.cli import main, validate, info, generate
+
+
+class TestCLI:
+    """Tests for CLI commands."""
+
+    def test_cli_help(self):
+        """Test CLI help output."""
+        runner = CliRunner()
+        result = runner.invoke(main, ["--help"])
+        assert result.exit_code == 0
+        assert "OpenAPI Mock Server" in result.output
+
+    def test_validate_valid_spec(self, temp_spec_file):
+        """Test validate command with valid spec."""
+        runner = CliRunner()
+        result = runner.invoke(validate, [temp_spec_file])
+        assert result.exit_code == 0
+        assert "Valid OpenAPI spec" in result.output
+
+    def test_validate_nonexistent_file(self):
+        """Test validate command with non-existent file."""
+        runner = CliRunner()
+        result = runner.invoke(validate, ["/nonexistent/spec.yaml"])
+        assert result.exit_code != 0
+        assert "not found" in result.output.lower()
+
+    def test_info_command(self, temp_spec_file, sample_openapi_spec):
+        """Test info command displays spec information."""
+        runner = CliRunner()
+        result = runner.invoke(info, [temp_spec_file])
+        assert result.exit_code == 0
+        assert "Test API" in result.output
+
+    def test_generate_command(self, temp_spec_file):
+        """Test generate command creates output."""
+        runner = CliRunner()
+        with tempfile.NamedTemporaryFile(mode="w", suffix=".py", delete=False) as f:
+            result = runner.invoke(generate, [temp_spec_file, "--output", f.name])
+            assert result.exit_code == 0
+            assert "Generated mock server" in result.output
+
+    def test_generate_to_stdout(self, temp_spec_file):
+        """Test generate command outputs to stdout."""
+        runner = CliRunner()
+        result = runner.invoke(generate, [temp_spec_file])
+        assert result.exit_code == 0
+        assert "Auto-generated mock server" in result.output
+
+    def test_start_command_help(self):
+        """Test start command help output."""
+        runner = CliRunner()
+        result = runner.invoke(main, ["start", "--help"])
+        assert result.exit_code == 0
+        assert "--port" in result.output
+        assert "--host" in result.output
+        assert "--delay" in result.output
+
+    def test_start_command_with_delay_option(self, temp_spec_file):
+        """Test start command accepts delay option."""
+        runner = CliRunner()
+        result = runner.invoke(main, ["start", temp_spec_file, "--delay", "0.5", "--port", "9999"])
+        assert result.exit_code == 0
+        assert "Response delay" in result.output
+
+    def test_start_command_with_delay_range(self, temp_spec_file):
+        """Test start command accepts delay range."""
+        runner = CliRunner()
+        result = runner.invoke(main, ["start", temp_spec_file, "--delay", "0.1,1.0", "--port", "9998"])
+        assert result.exit_code == 0
+        assert "Response delay" in result.output
+
+    def test_start_command_with_invalid_delay(self, temp_spec_file):
+        """Test start command rejects invalid delay."""
+        runner = CliRunner()
+        result = runner.invoke(main, ["start", temp_spec_file, "--delay", "invalid"])
+        assert result.exit_code != 0
+        assert "Invalid delay format" in result.output
+
+    def test_start_command_with_auth(self, temp_spec_file):
+        """Test start command accepts auth option."""
+        runner = CliRunner()
+        result = runner.invoke(main, ["start", temp_spec_file, "--auth", "bearer", "--port", "9997"])
+        assert result.exit_code == 0
+        assert "Authentication enabled" in result.output
+
+    def test_start_command_with_watch(self, temp_spec_file):
+        """Test start command with watch flag."""
+        runner = CliRunner()
+        result = runner.invoke(main, ["start", temp_spec_file, "--watch", "--port", "9996"])
+        assert result.exit_code == 0
+        assert "Watching" in result.output
+
+    def test_port_validation(self, temp_spec_file):
+        """Test port validation rejects invalid ports."""
+        runner = CliRunner()
+        result = runner.invoke(main, ["start", temp_spec_file, "--port", "70000"])
+        assert result.exit_code != 0
+        assert "between 1 and 65535" in result.output
+
+    def test_auth_type_validation(self, temp_spec_file):
+        """Test auth type validation."""
+        runner = CliRunner()
+        result = runner.invoke(main, ["start", temp_spec_file, "--auth", "invalid"])
+        assert result.exit_code != 0