[1856] Use a dummy database_file for lettuce multi_instance test

tests/lettuce/configurations/multi_instance/multi_auth.config.orig

@@ -1 +1,24 @@
-{"version": 2, "Logging": {"loggers": [{"severity": "DEBUG", "name": "*", "debuglevel": 99}]}, "Auth": {"listen_on": [{"port": 47806, "address": "0.0.0.0"}]}, "Boss": {"components": {"b10-auth-2": {"kind": "dispensable", "special": "auth"}, "b10-auth": {"kind": "dispensable", "special": "auth"}, "b10-cmdctl": {"kind": "needed", "special": "cmdctl"}}}}
+{
+    "version": 2,
+    "Logging": {
+        "loggers": [ {
+            "debuglevel": 99,
+            "severity": "DEBUG",
+            "name": "*"
+        } ]
+    },
+    "Auth": {
+        "database_file": "data/test_nonexistent_db.sqlite3",
+        "listen_on": [ {
+            "port": 47806,
+            "address": "127.0.0.1"
+        } ]
+    },
+    "Boss": {
+        "components": {
+            "b10-auth-2": {"kind": "dispensable", "special": "auth"},
+            "b10-auth": {"kind": "dispensable", "special": "auth"},
+            "b10-cmdctl": {"kind": "needed", "special": "cmdctl"}
+        }
+    }
+}

tests/lettuce/features/multi_instance.feature

@@ -3,6 +3,10 @@ Feature: Multiple instances
     removing them does not affect the running of other instances
 
     Scenario: Multiple instances of Auth
+        # Standard check to test (non-)existence of a file
+        # This file is actually automatically
+        The file data/test_nonexistent_db.sqlite3 should not exist
+
         # This config should have two running instances
         Given I have bind10 running with configuration multi_instance/multi_auth.config
         And wait for bind10 stderr message BIND10_STARTED_CC
@@ -21,6 +25,9 @@ Feature: Multiple instances
         And bind10 module Stats should not be running
         And bind10 module StatsHttpd should not be running
 
+        # Now we use the first step again to see if the file has been created
+        The file data/test_nonexistent_db.sqlite3 should exist
+
         A query for example.com should have rcode REFUSED
 
         # this also checks whether the process is running