add unit test for error handling in build_config()

app/src/server.py

@@ -137,7 +137,7 @@ class Server():
 
         if config_err is not None:
             logging.info(f'config_err: {config_err}')
-            return  # fixme raise an exception
+            return
 
         logging.info('******')
 
@@ -239,7 +239,9 @@ async def healthy():
     return Response(status=200, response="I'm fine")
 
 
-async def handle_client(reader: StreamReader, writer: StreamWriter, inv_class):
+async def handle_client(reader: StreamReader,
+                        writer: StreamWriter,
+                        inv_class):    # pragma: no cover
     '''Handles a new incoming connection and starts an async loop'''
 
     with inv_class(reader, writer) as inv:
@@ -247,7 +249,7 @@ async def handle_client(reader: StreamReader, writer: StreamWriter, inv_class):
 
 
 @app.before_serving
-async def startup_app():
+async def startup_app():    # pragma: no cover
     HypercornLogHndl.save()
     loop = asyncio.get_event_loop()
     Proxy.class_init()

app/tests/cnf/invalid_config.toml

@@ -0,0 +1 @@
+mqtt.port    = ":1883"

app/tests/test_server.py

@@ -123,6 +123,17 @@ class TestServerClass:
         assert logging.getLogger('hypercorn.access').level == logging.INFO
         assert logging.getLogger('hypercorn.error').level == logging.INFO
 
+    def test_build_config_error(self, caplog):
+        s = self.FakeServer()
+        s.src_dir = 'app/src/'
+        s.toml_config = 'app/tests/cnf/invalid_config.toml'
+
+        with caplog.at_level(logging.ERROR):
+            s.build_config()
+        assert "Can't read from app/tests/cnf/invalid_config.toml" in caplog.text
+        assert "Key 'port' error:" in caplog.text
+
+
 class TestHypercornLogHndl:
     class FakeServer(Server):
         def __init__(self):