tests: update app settings test

The original test no longer makes sense since connections don't
timeout. To somehow test that new connections have the settings,
convert it to flush the pool instead.

test/io/test_io.py

@@ -588,9 +588,9 @@ def test_iat_claim(defaultenv):
             time.sleep(0.1)
 
 
-def test_app_settings(defaultenv):
+def test_app_settings_flush_pool(defaultenv):
     """
-    App settings should not reset when the db pool times out.
+    App settings should not reset when the db pool is flushed.
 
     See: https://github.com/PostgREST/postgrest/issues/1141
 
@@ -599,12 +599,16 @@ def test_app_settings(defaultenv):
     env = {**defaultenv, "PGRST_APP_SETTINGS_EXTERNAL_API_SECRET": "0123456789abcdef"}
 
     with run(env=env) as postgrest:
-        # Wait for the db pool to time out, set to 1s in config
-        time.sleep(2)
-
         uri = "/rpc/get_guc_value?name=app.settings.external_api_secret"
         response = postgrest.session.get(uri)
+        assert response.text == '"0123456789abcdef"'
 
+        # SIGUSR1 causes the postgres connection pool to be flushed
+        postgrest.process.send_signal(signal.SIGUSR1)
+        time.sleep(0.1)
+
+        uri = "/rpc/get_guc_value?name=app.settings.external_api_secret"
+        response = postgrest.session.get(uri)
         assert response.text == '"0123456789abcdef"'