1 files changed, 61 insertions, 1 deletions
diff --git a/src/mailman/testing/layers.py b/src/mailman/testing/layers.py
index 4a9841fc2..c1346b29f 100644
--- a/src/mailman/testing/layers.py
+++ b/src/mailman/testing/layers.py
@@ -47,13 +47,16 @@ import tempfile
 
 from lazr.config import as_boolean
 from pkg_resources import resource_string
+from sqlalchemy import MetaData
 from textwrap import dedent
+from zope import event
 from zope.component import getUtility
 
 from mailman.config import config
 from mailman.core import initialize
 from mailman.core.initialize import INHIBIT_CONFIG_FILE
 from mailman.core.logging import get_handler
+from mailman.database.model import Model
 from mailman.database.transaction import transaction
 from mailman.interfaces.domain import IDomainManager
 from mailman.testing.helpers import (
@@ -98,7 +101,9 @@ class ConfigLayer(MockAndMonkeyLayer):
         # Set up the basic configuration stuff.  Turn off path creation until
         # we've pushed the testing config.
         config.create_paths = False
-        initialize.initialize_1(INHIBIT_CONFIG_FILE)
+        if not event.subscribers:
+            # only if not yet initialized by another layer
+            initialize.initialize_1(INHIBIT_CONFIG_FILE)
         assert cls.var_dir is None, 'Layer already set up'
         # Calculate a temporary VAR_DIR directory so that run-time artifacts
         # of the tests won't tread on the installation's data.  This also
@@ -310,6 +315,61 @@ class RESTLayer(SMTPLayer):
 
 
 
+class DatabaseLayer:
+    """Layer for database tests"""
+
+    var_dir = None
+
+    @classmethod
+    def _drop_all_tables(cls):
+        Model.metadata.drop_all(config.db.engine)
+        md = MetaData()
+        md.reflect(bind=config.db.engine)
+        if "alembic_version" in md.tables:
+            md.tables["alembic_version"].drop(config.db.engine)
+
+    @classmethod
+    def setUp(cls):
+        # Set up the basic configuration stuff. Turn off path creation.
+        config.create_paths = False
+        if not event.subscribers:
+            # only if not yet initialized by another layer
+            initialize.initialize_1(INHIBIT_CONFIG_FILE)
+        # Don't initialize the database.
+        cls.var_dir = tempfile.mkdtemp()
+        test_config = dedent("""
+        [mailman]
+        layout: testing
+        [paths.testing]
+        var_dir: {0}
+        [devmode]
+        testing: yes
+        """.format(cls.var_dir))
+        # Read the testing config and push it.
+        test_config += resource_string('mailman.testing', 'testing.cfg')
+        config.create_paths = True
+        config.push('test config', test_config)
+        # Write the configuration file for subprocesses and set up the config
+        # object to pass that properly on the -C option.
+        config_file = os.path.join(cls.var_dir, 'test.cfg')
+        with open(config_file, 'w') as fp:
+            fp.write(test_config)
+            print(file=fp)
+        config.filename = config_file
+
+    @classmethod
+    def tearDown(cls):
+        assert cls.var_dir is not None, 'Layer not set up'
+        shutil.rmtree(cls.var_dir)
+        config.pop('test config')
+        cls.var_dir = None
+
+    @classmethod
+    def testTearDown(cls):
+        cls._drop_all_tables()
+
+
+
 def is_testing():
     """Return a 'testing' flag for use with the predictable factories.