Improve 404 handling

freqtrade/rpc/api_server.py

@@ -156,7 +156,7 @@ class ApiServer(RPC):
         """
         return self.rest_dump({
             'status': 'error',
-            'reason': '''There's no API call for %s''' % request.base_url,
+            'reason': f"There's no API call for {request.base_url}.",
             'code': 404
         }), 404
 

freqtrade/tests/rpc/test_rpc_apiserver.py

@@ -29,6 +29,18 @@ def response_success_assert(response):
     assert response.content_type == "application/json"
 
 
+def test_api_not_found(botclient):
+    ftbot, client = botclient
+
+    rc = client.post("/invalid_url")
+    assert rc.status_code == 404
+    assert rc.content_type == "application/json"
+    assert rc.json == {'status': 'error',
+                       'reason': "There's no API call for http://localhost/invalid_url.",
+                       'code': 404
+                       }
+
+
 def test_api_stop_workflow(botclient):
     ftbot, client = botclient
     assert ftbot.state == State.RUNNING