Added custom log function; started tests

tests/test_logger.py

@@ -0,0 +1,23 @@
+"""Tests for the logger module."""
+from app.logger import Logger
+from datetime import datetime
+
+
+def test_custom_stdout(capfd):
+    """Test the custom command."""
+    logger = Logger()
+
+    timestamp = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
+    logger.custom("a message", header="cewl")
+
+    out, _ = capfd.readouterr()
+
+    assert out == f"[{timestamp}][cewl] a message\n"
+
+
+def test_log_stdout(capfd):
+    """Test the log command with several levels."""
+
+    logger = Logger()
+
+    # TODO