feat: add shell-completions subcommand (#76)

tests/test_cli_main.py

@@ -0,0 +1,21 @@
+from click.testing import CliRunner
+from goose.cli.main import get_current_shell, shell_completions
+
+
+def test_get_current_shell(mocker):
+    mocker.patch("os.getenv", return_value="/bin/bash")
+    assert get_current_shell() == "bash"
+
+
+def test_shell_completions_install_invalid_combination():
+    runner = CliRunner()
+    result = runner.invoke(shell_completions, ["--install", "--generate", "bash"])
+    assert result.exit_code != 0
+    assert "Only one of --install or --generate can be specified" in result.output
+
+
+def test_shell_completions_install_no_option():
+    runner = CliRunner()
+    result = runner.invoke(shell_completions, ["bash"])
+    assert result.exit_code != 0
+    assert "One of --install or --generate must be specified" in result.output