test(logging): add tests for centralized logging helpers

Add parametrized tests for resolve_log_level() covering valid levels,
invalid fallback, and unset default. Add tests for create_log_handler()
verifying TTY returns RichHandler, non-TTY returns StreamHandler with
the correct format.

Update test_uvicorn_runner.py to import resolve_log_level from log
instead of the deleted private _resolve_log_level from runners.uvicorn.

Signed-off-by: Major Hayden <major@redhat.com>

Author: major

tests/unit/runners/test_uvicorn_runner.py

@@ -7,8 +7,9 @@
 from pytest_mock import MockerFixture
 
 from constants import LIGHTSPEED_STACK_LOG_LEVEL_ENV_VAR
+from log import resolve_log_level
 from models.config import ServiceConfiguration, TLSConfiguration
-from runners.uvicorn import _resolve_log_level, start_uvicorn
+from runners.uvicorn import start_uvicorn
 
 
 def test_start_uvicorn(mocker: MockerFixture) -> None:
@@ -146,17 +147,17 @@ def test_start_uvicorn_with_root_path(mocker: MockerFixture) -> None:
 def test_resolve_log_level_from_env(
     monkeypatch: pytest.MonkeyPatch, env_value: str, expected_level: int
 ) -> None:
-    """Test that _resolve_log_level resolves env var values to logging constants."""
+    """Test that resolve_log_level resolves env var values to logging constants."""
     monkeypatch.setenv(LIGHTSPEED_STACK_LOG_LEVEL_ENV_VAR, env_value)
-    assert _resolve_log_level() == expected_level
+    assert resolve_log_level() == expected_level
 
 
 def test_resolve_log_level_defaults_to_info(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
-    """Test that _resolve_log_level falls back to INFO when the env var is unset."""
+    """Test that resolve_log_level falls back to INFO when the env var is unset."""
     monkeypatch.delenv(LIGHTSPEED_STACK_LOG_LEVEL_ENV_VAR, raising=False)
-    assert _resolve_log_level() == logging.INFO
+    assert resolve_log_level() == logging.INFO
 
 
 def test_start_uvicorn_respects_debug_log_level(

tests/unit/test_log.py

@@ -1,10 +1,13 @@
 """Unit tests for functions defined in src/log.py."""
 
 import logging
+
 import pytest
+from pytest_mock import MockerFixture
+from rich.logging import RichHandler
 
-from log import get_logger
-from constants import LIGHTSPEED_STACK_LOG_LEVEL_ENV_VAR
+from log import get_logger, resolve_log_level, create_log_handler
+from constants import LIGHTSPEED_STACK_LOG_LEVEL_ENV_VAR, DEFAULT_LOG_FORMAT
 
 
 def test_get_logger() -> None:
@@ -57,3 +60,59 @@ def test_get_logger_default_log_level(monkeypatch: pytest.MonkeyPatch) -> None:
 
     logger = get_logger("test_default")
     assert logger.level == logging.INFO
+
+
+@pytest.mark.parametrize(
+    ("level_name", "expected_level"),
+    [
+        ("DEBUG", logging.DEBUG),
+        ("debug", logging.DEBUG),
+        ("INFO", logging.INFO),
+        ("WARNING", logging.WARNING),
+        ("ERROR", logging.ERROR),
+        ("CRITICAL", logging.CRITICAL),
+        ("critical", logging.CRITICAL),
+    ],
+)
+def test_resolve_log_level(
+    monkeypatch: pytest.MonkeyPatch, level_name: str, expected_level: int
+) -> None:
+    """Test that resolve_log_level correctly resolves valid level names."""
+    monkeypatch.setenv(LIGHTSPEED_STACK_LOG_LEVEL_ENV_VAR, level_name)
+    assert resolve_log_level() == expected_level
+
+
+def test_resolve_log_level_invalid_fallback(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Test that resolve_log_level falls back to INFO for invalid values."""
+    monkeypatch.setenv(LIGHTSPEED_STACK_LOG_LEVEL_ENV_VAR, "BOGUS")
+    assert resolve_log_level() == logging.INFO
+
+
+def test_resolve_log_level_default(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Test that resolve_log_level defaults to INFO when env var is unset."""
+    monkeypatch.delenv(LIGHTSPEED_STACK_LOG_LEVEL_ENV_VAR, raising=False)
+    assert resolve_log_level() == logging.INFO
+
+
+def test_create_log_handler_tty(mocker: MockerFixture) -> None:
+    """Test that create_log_handler returns RichHandler when TTY is available."""
+    mocker.patch("sys.stderr.isatty", return_value=True)
+    handler = create_log_handler()
+    assert isinstance(handler, RichHandler)
+
+
+def test_create_log_handler_non_tty(mocker: MockerFixture) -> None:
+    """Test that create_log_handler returns StreamHandler when no TTY."""
+    mocker.patch("sys.stderr.isatty", return_value=False)
+    handler = create_log_handler()
+    assert isinstance(handler, logging.StreamHandler)
+    assert not isinstance(handler, RichHandler)
+
+
+def test_create_log_handler_non_tty_format(mocker: MockerFixture) -> None:
+    """Test that non-TTY handler uses DEFAULT_LOG_FORMAT."""
+    mocker.patch("sys.stderr.isatty", return_value=False)
+    handler = create_log_handler()
+    assert handler.formatter is not None
+    # pylint: disable=protected-access
+    assert handler.formatter._fmt == DEFAULT_LOG_FORMAT