Test Gunicorn settings

#11
https://docs.gunicorn.org/en/latest/settings.html#print-config
https://docs.pytest.org/en/latest/how-to/capture-stdout-stderr.html

The Gunicorn configuration file was technically covered by unit tests,
but the individual settings were not tested. This commit will add tests
of the Gunicorn settings. The tests use Gunicorn's `--print-config`
option to load and output the configuration. The pytest fixture `capfd`
is used to read the Gunicorn output.

Author: br3ndonland

tests/test_gunicorn_conf.py

@@ -1,4 +1,6 @@
 import multiprocessing
+import subprocess
+from pathlib import Path
 from typing import Optional
 
 import pytest
@@ -50,3 +52,81 @@ def test_calculate_workers_both_max_and_total(
         """
         result = gunicorn_conf.calculate_workers(max_workers, total_workers)
         assert result == min(int(max_workers), int(total_workers))
+
+
+class TestGunicornSettings:
+    """Test Gunicorn configuration setup and settings.
+    ---
+    """
+
+    @pytest.mark.parametrize("module", ("base", "fastapi", "starlette"))
+    @pytest.mark.timeout(2)
+    def test_gunicorn_config(self, capfd: pytest.CaptureFixture, module: str) -> None:
+        """Load Gunicorn configuration file and verify output."""
+        app_module = f"inboard.app.main_{module}:app"
+        gunicorn_conf_path = gunicorn_conf.__file__
+        gunicorn_options = [
+            "gunicorn",
+            "--print-config",
+            "-c",
+            gunicorn_conf_path,
+            "-k",
+            "uvicorn.workers.UvicornWorker",
+            app_module,
+        ]
+        subprocess.run(gunicorn_options)
+        captured = capfd.readouterr()
+        captured_and_cleaned = captured.out.replace(" ", "").splitlines()
+        assert app_module in captured.out
+        assert gunicorn_conf_path in captured.out
+        assert "INFO" in captured.out
+        assert "uvicorn.logging.DefaultFormatter" in captured.out
+        assert "graceful_timeout=120" in captured_and_cleaned
+        assert "keepalive=5" in captured_and_cleaned
+        assert "loglevel=info" in captured_and_cleaned
+        assert "timeout=120" in captured_and_cleaned
+        assert f"workers={max(multiprocessing.cpu_count(), 2)}" in captured_and_cleaned
+
+    @pytest.mark.parametrize("module", ("base", "fastapi", "starlette"))
+    @pytest.mark.timeout(2)
+    def test_gunicorn_config_with_custom_options(
+        self,
+        capfd: pytest.CaptureFixture,
+        gunicorn_conf_tmp_file_path: Path,
+        logging_conf_tmp_file_path: Path,
+        monkeypatch: pytest.MonkeyPatch,
+        module: str,
+    ) -> None:
+        """Customize options, load Gunicorn configuration file and verify output."""
+        app_module = f"inboard.app.main_{module}:app"
+        gunicorn_conf_path = str(gunicorn_conf_tmp_file_path)
+        logging_conf_file = f"{logging_conf_tmp_file_path}/tmp_log.py"
+        monkeypatch.setenv("GRACEFUL_TIMEOUT", "240")
+        monkeypatch.setenv("KEEP_ALIVE", "10")
+        monkeypatch.setenv("LOG_FORMAT", "verbose")
+        monkeypatch.setenv("LOG_LEVEL", "debug")
+        monkeypatch.setenv("LOGGING_CONF", logging_conf_file)
+        monkeypatch.setenv("MAX_WORKERS", "10")
+        monkeypatch.setenv("TIMEOUT", "240")
+        monkeypatch.setenv("WEB_CONCURRENCY", "15")
+        gunicorn_options = [
+            "gunicorn",
+            "--print-config",
+            "-c",
+            gunicorn_conf_path,
+            "-k",
+            "uvicorn.workers.UvicornWorker",
+            app_module,
+        ]
+        subprocess.run(gunicorn_options)
+        captured = capfd.readouterr()
+        captured_and_cleaned = captured.out.replace(" ", "").splitlines()
+        assert app_module in captured.out
+        assert gunicorn_conf_path in captured.out
+        assert "DEBUG" in captured.out
+        assert "uvicorn.logging.DefaultFormatter" in captured.out
+        assert "graceful_timeout=240" in captured_and_cleaned
+        assert "keepalive=10" in captured_and_cleaned
+        assert "loglevel=debug" in captured_and_cleaned
+        assert "timeout=240" in captured_and_cleaned
+        assert "workers=10" in captured_and_cleaned