test_cli: add empty args test, use pytest fixtures pattern

tests/test_cli.py

@@ -1,9 +1,11 @@
 import pytest
-from kartograf.cli import create_parser
+from kartograf.cli import create_parser, main
 
-parser = create_parser()
+@pytest.fixture(name="parser")
+def fixture_parser():
+    return create_parser()
 
-def test_map_command():
+def test_map_command(parser):
     args = parser.parse_args(['map'])
     assert args.command == 'map'
     assert args.debug is True  # default is True
@@ -14,35 +16,42 @@ def test_map_command():
     assert args.epoch is None
     assert args.max_encode == 33521664
 
-def test_map_with_options():
+def test_map_with_options(parser):
     args = parser.parse_args(['map', '-c', '-irr', '-rv', '-r', '/path', '-t', '123'])
     assert args.cleanup is True
     assert args.irr is True
     assert args.routeviews is True
     assert args.reproduce == '/path'
     assert args.epoch == '123'
 
-def test_merge_command():
+def test_merge_command(parser):
     args = parser.parse_args(['merge'])
     assert args.command == 'merge'
     assert args.base.endswith('base_file.txt')
     assert args.extra.endswith('extra_file.txt')
     assert args.output.endswith('out_file.txt')
 
-def test_cov_command(capsys):
+def test_cov_command(parser, capsys):
     with pytest.raises(SystemExit):
         # Should fail without required arguments
         parser.parse_args(['cov'])
     captured = capsys.readouterr()
     assert captured.err.startswith("usage:")
 
-def test_invalid_command(capsys):
+def test_help(capsys):
+    with pytest.raises(SystemExit) as e:
+        main([])
+    assert e.value.code == "Please provide a command."
+    captured = capsys.readouterr()
+    assert captured.out.startswith("usage:")
+
+def test_invalid_command(parser, capsys):
     with pytest.raises(SystemExit):
         parser.parse_args(['invalid'])
     captured = capsys.readouterr()
     assert captured.err.startswith("usage:")
 
-def test_version_flag(capsys):
+def test_version_flag(parser, capsys):
     with pytest.raises(SystemExit) as excinfo:
         parser.parse_args(['--version'])
     assert excinfo.value.code == 0