remove output arg, > file is enough

src/requirements_compare/main.py

@@ -148,23 +148,26 @@ def generate_changes(
     return "\r\n".join(description)
 
 
+def main(requirements_file: pathlib.Path, output_file: pathlib.Path) -> None:
+    added, updated, removed = compare_requirements(requirements_file)
+    if output_file == pathlib.Path():
+        return typer.echo(generate_changes(added, updated, removed), file=sys.stdout)
+
+    with output_file.open("w") as file:
+        typer.echo(generate_changes(added, updated, removed), file=file)
+
+
 @app.command()
-def main(
+def rc(
     requirements_file: typing.Annotated[
         pathlib.Path, typer.Argument(help="The updated requirements file to compare")
     ],
-    output_file: typing.Annotated[
-        pathlib.Path, typer.Argument(help="Where to write the output")
-    ]
-    | None = None,
 ) -> None:
     """
     Compare a local requirements file to its HEAD version and generate a description of
     the changes.
     """
-    added, updated, removed = compare_requirements(requirements_file)
-    with output_file.open("w") if output_file else sys.stdout as file:
-        typer.echo(generate_changes(added, updated, removed), file=file)
+    main(requirements_file, pathlib.Path())
 
 
 if __name__ == "__main__":

tests/conftest.py

+import io
+import pathlib
+
+import pytest
+
+
+@pytest.fixture(autouse=True)
+def retrieve_requirements(monkeypatch):
+    def mock_retrieve_requirements(requirements_file):
+        return io.StringIO("example_package==1.0.0")
+
+    monkeypatch.setattr(
+        "requirements_compare.main.retrieve_requirements",
+        mock_retrieve_requirements,
+    )
+
+
+@pytest.fixture
+def requirements_file() -> pathlib.Path:
+    requirements_file_ = pathlib.Path("requirements.txt")
+    yield requirements_file_
+    requirements_file_.unlink()
+
+
+@pytest.fixture
+def output_file() -> pathlib.Path:
+    output_file_ = pathlib.Path("output.txt")
+    yield output_file_
+    output_file_.unlink()

tests/test_cli.py

+import typer.testing
+
+from requirements_compare import app
+
+runner = typer.testing.CliRunner()
+
+
+def test_app_2(requirements_file):
+    requirements_file.write_text(
+        "example_package==2.0.0\nlast_package==1.0.0",
+    )
+
+    result = runner.invoke(app, [requirements_file.name])
+    assert result.exit_code == 0
+    assert "added `last_package` version `1.0.0`" in result.stdout.lower()
+    assert "bump `example_package` from `1.0.0` to `2.0.0`" in result.stdout.lower()

tests/test_requirements_compare.py

 """Sample test module."""
 import io
-import pathlib
 
 import pytest
 
 from requirements_compare.main import main
 
 
-@pytest.fixture(autouse=True)
-def retrieve_requirements(monkeypatch):
-    def mock_retrieve_requirements(requirements_file):
-        return io.StringIO("example_package==1.0.0")
-
-    monkeypatch.setattr(
-        "requirements_compare.main.retrieve_requirements",
-        mock_retrieve_requirements,
-    )
-
-
-@pytest.fixture
-def requirements_file() -> pathlib.Path:
-    requirements_file_ = pathlib.Path("requirements.txt")
-    yield requirements_file_
-    requirements_file_.unlink()
-
-
-@pytest.fixture
-def output_file() -> pathlib.Path:
-    output_file_ = pathlib.Path("output.txt")
-    yield output_file_
-    output_file_.unlink()
-
-
 def test_removed(requirements_file, output_file):
     """Test main function."""
     requirements_file.write_text("")