Fix failing tests with random 504

Do not update global config variable for gevent mode. Make sure we do not use gevent env for tests apart of dedicated tests.
In those tests mock configuration rather than modifing global variable.

Author: varmar05

server/.test.env

@@ -24,3 +24,4 @@ SECURITY_BEARER_SALT='bearer'
 SECURITY_EMAIL_SALT='email'
 SECURITY_PASSWORD_SALT='password'
 DIAGNOSTIC_LOGS_DIR=/tmp/diagnostic_logs
+GEVENT_WORKER=0

server/mergin/tests/test_middleware.py

@@ -6,6 +6,7 @@
 import psycogreen.gevent
 import pytest
 import sqlalchemy
+from unittest.mock import patch
 
 from ..app import create_simple_app, GeventTimeoutMiddleware, db
 from ..config import Configuration
@@ -14,58 +15,74 @@
 @pytest.mark.parametrize("use_middleware", [True, False])
 def test_use_middleware(use_middleware):
     """Test using middleware"""
-    Configuration.GEVENT_WORKER = use_middleware
-    Configuration.GEVENT_REQUEST_TIMEOUT = 1
-    application = create_simple_app()
+    with patch.object(
+        Configuration,
+        "GEVENT_WORKER",
+        use_middleware,
+    ), patch.object(
+        Configuration,
+        "GEVENT_REQUEST_TIMEOUT",
+        1,
+    ):
+        application = create_simple_app()
 
-    def ping():
-        gevent.sleep(Configuration.GEVENT_REQUEST_TIMEOUT + 1)
-        return "pong"
+        def ping():
+            gevent.sleep(Configuration.GEVENT_REQUEST_TIMEOUT + 1)
+            return "pong"
 
-    application.add_url_rule("/test", "ping", ping)
-    app_context = application.app_context()
-    app_context.push()
+        application.add_url_rule("/test", "ping", ping)
+        app_context = application.app_context()
+        app_context.push()
 
-    assert isinstance(application.wsgi_app, GeventTimeoutMiddleware) == use_middleware
-    # in case of gevent, dummy endpoint it set to time out
-    assert application.test_client().get("/test").status_code == (
-        504 if use_middleware else 200
-    )
+        assert (
+            isinstance(application.wsgi_app, GeventTimeoutMiddleware) == use_middleware
+        )
+        # in case of gevent, dummy endpoint it set to time out
+        assert application.test_client().get("/test").status_code == (
+            504 if use_middleware else 200
+        )
 
 
 def test_catch_timeout():
     """Test proper handling of gevent timeout with db.session.rollback"""
     psycogreen.gevent.patch_psycopg()
-    Configuration.GEVENT_WORKER = True
-    Configuration.GEVENT_REQUEST_TIMEOUT = 1
-    application = create_simple_app()
+    with patch.object(
+        Configuration,
+        "GEVENT_WORKER",
+        True,
+    ), patch.object(
+        Configuration,
+        "GEVENT_REQUEST_TIMEOUT",
+        1,
+    ):
+        application = create_simple_app()
 
-    def unhandled():
-        try:
-            db.session.execute("SELECT pg_sleep(1.1);")
-        finally:
-            db.session.execute("SELECT 1;")
-        return ""
+        def unhandled():
+            try:
+                db.session.execute("SELECT pg_sleep(1.1);")
+            finally:
+                db.session.execute("SELECT 1;")
+            return ""
 
-    def timeout():
-        try:
-            db.session.execute("SELECT pg_sleep(1.1);")
-        except gevent.timeout.Timeout:
-            db.session.rollback()
-            raise
-        finally:
-            db.session.execute("SELECT 1;")
-        return ""
+        def timeout():
+            try:
+                db.session.execute("SELECT pg_sleep(1.1);")
+            except gevent.timeout.Timeout:
+                db.session.rollback()
+                raise
+            finally:
+                db.session.execute("SELECT 1;")
+            return ""
 
-    application.add_url_rule("/unhandled", "unhandled", unhandled)
-    application.add_url_rule("/timeout", "timeout", timeout)
-    app_context = application.app_context()
-    app_context.push()
+        application.add_url_rule("/unhandled", "unhandled", unhandled)
+        application.add_url_rule("/timeout", "timeout", timeout)
+        app_context = application.app_context()
+        app_context.push()
 
-    assert application.test_client().get("/timeout").status_code == 504
+        assert application.test_client().get("/timeout").status_code == 504
 
-    # in case of missing rollback sqlalchemy would raise error
-    with pytest.raises(sqlalchemy.exc.PendingRollbackError):
-        application.test_client().get("/unhandled")
+        # in case of missing rollback sqlalchemy would raise error
+        with pytest.raises(sqlalchemy.exc.PendingRollbackError):
+            application.test_client().get("/unhandled")
 
-    db.session.rollback()
+        db.session.rollback()