add version command to show current version

tests/test_cli.py

@@ -0,0 +1,33 @@
+from pathlib import Path
+
+from click.testing import CliRunner
+from unittest.mock import patch
+
+from browser_cli.cli import main, _project_version
+
+
+def _expected_version() -> str:
+    pyproject = Path(__file__).resolve().parent.parent / "pyproject.toml"
+    for line in pyproject.read_text(encoding="utf-8").splitlines():
+        if line.startswith("version = "):
+            return line.split('"')[1]
+    raise AssertionError("version not found in pyproject.toml")
+
+
+def test_short_version_option():
+    result = CliRunner().invoke(main, ["-V"])
+    assert result.exit_code == 0
+    assert result.output.strip() == _expected_version()
+
+
+def test_long_version_option():
+    result = CliRunner().invoke(main, ["--version"])
+    assert result.exit_code == 0
+    assert result.output.strip() == _expected_version()
+
+
+def test_project_version_falls_back_to_installed_package_metadata():
+    with patch("browser_cli.cli.Path.read_text", side_effect=OSError), patch(
+        "browser_cli.cli.package_version", return_value="9.9.9"
+    ):
+        assert _project_version() == "9.9.9"