Add unit tests

tests/test_utilities.py

@@ -0,0 +1,26 @@
+from bmspy.utilities import debugger
+
+
+class TestDebugger:
+    def test_prints_message(self, capsys):
+        debugger("hello world")
+        captured = capsys.readouterr()
+        assert "hello world" in captured.out
+
+    def test_includes_timestamp(self, capsys):
+        debugger("test")
+        captured = capsys.readouterr()
+        # timestamp is prepended
+        assert "test" in captured.out
+        assert len(captured.out.strip()) > len("test")
+
+    def test_pretty_true(self, capsys):
+        debugger({"key": "value"}, pretty=True)
+        captured = capsys.readouterr()
+        # pretty-printed output includes the data key
+        assert "key" in captured.out
+
+    def test_pretty_false_no_pprint(self, capsys):
+        debugger("simple message", pretty=False)
+        captured = capsys.readouterr()
+        assert "simple message" in captured.out