test(v1.4.0-p2): add failing tests for milestones and columns

RED phase: 5 tests in test_collector.py (collect_milestones),
10 tests in test_display.py (render_milestones, parse_columns),
2 tests in test_exporter.py (milestones JSON), 7 tests in
test_cli.py (--milestones, --columns).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_cli.py

@@ -389,3 +389,94 @@ class TestMainFormatJson:
         captured = capsys.readouterr()
         parsed = json.loads(captured.out)
         assert isinstance(parsed, list)
+
+
+class TestParseArgsMilestones:
+    """Test --milestones argument parsing."""
+
+    def test_parse_args_milestones(self):
+        """--milestones sets milestones=True."""
+        from gitea_dashboard.cli import parse_args
+
+        args = parse_args(["--milestones"])
+        assert args.milestones is True
+
+    def test_parse_args_milestones_default(self):
+        """Without --milestones, milestones is False."""
+        from gitea_dashboard.cli import parse_args
+
+        args = parse_args([])
+        assert args.milestones is False
+
+
+class TestParseArgsColumns:
+    """Test --columns argument parsing."""
+
+    def test_parse_args_columns(self):
+        """--columns name,issues sets columns='name,issues'."""
+        from gitea_dashboard.cli import parse_args
+
+        args = parse_args(["--columns", "name,issues"])
+        assert args.columns == "name,issues"
+
+    def test_parse_args_columns_default(self):
+        """Without --columns, columns is None."""
+        from gitea_dashboard.cli import parse_args
+
+        args = parse_args([])
+        assert args.columns is None
+
+
+class TestMainMilestonesMode:
+    """Test main() with --milestones."""
+
+    @patch("gitea_dashboard.cli.render_milestones")
+    @patch("gitea_dashboard.cli.collect_milestones")
+    @patch("gitea_dashboard.cli.GiteaClient")
+    def test_main_milestones_mode(self, mock_client_cls, mock_collect_ms, mock_render_ms):
+        """--milestones routes to collect_milestones + render_milestones."""
+        env = {"GITEA_TOKEN": "test-tok"}
+        mock_client_cls.return_value = MagicMock()
+        mock_collect_ms.return_value = []
+
+        with patch.dict("os.environ", env, clear=True):
+            main(["--milestones"])
+
+        mock_collect_ms.assert_called_once()
+        mock_render_ms.assert_called_once()
+
+
+class TestMainColumnsHelp:
+    """Test main() with --columns help."""
+
+    @patch("gitea_dashboard.cli.GiteaClient")
+    def test_main_columns_help(self, mock_client_cls, capsys):
+        """--columns help displays available columns and exits."""
+        env = {"GITEA_TOKEN": "test-tok"}
+        mock_client_cls.return_value = MagicMock()
+
+        with patch.dict("os.environ", env, clear=True):
+            main(["--columns", "help"])
+
+        captured = capsys.readouterr()
+        # Should list column names
+        assert "name" in captured.out or "name" in captured.err
+
+    @patch("gitea_dashboard.cli.render_dashboard")
+    @patch("gitea_dashboard.cli.collect_all")
+    @patch("gitea_dashboard.cli.GiteaClient")
+    def test_main_no_desc_and_columns_compat(self, mock_client_cls, mock_collect, mock_render):
+        """--no-desc and --columns -commit both apply cumulatively."""
+        env = {"GITEA_TOKEN": "test-tok"}
+        mock_client_cls.return_value = MagicMock()
+        mock_collect.return_value = []
+
+        with patch.dict("os.environ", env, clear=True):
+            main(["--no-desc", "--columns", "-commit"])
+
+        # render_dashboard should be called with columns excluding both description and commit
+        call_kwargs = mock_render.call_args
+        columns = call_kwargs[1].get("columns") if call_kwargs[1] else None
+        if columns is not None:
+            assert "description" not in columns
+            assert "commit" not in columns