Add progress log regression test

tests-unit/app_test/logger_test.py

@@ -0,0 +1,15 @@
+from collections import deque
+import io
+
+import app.logger
+
+
+def test_carriage_return_can_be_first_log_entry(monkeypatch):
+    monkeypatch.setattr(app.logger, "logs", deque())
+    stream = io.TextIOWrapper(io.BytesIO(), encoding="utf-8")
+    interceptor = app.logger.LogInterceptor(stream)
+
+    interceptor.write("\rprogress")
+
+    assert len(app.logger.logs) == 1
+    assert app.logger.logs[0]["m"] == "\rprogress"