diff --git a/activitypub/database/base.py b/activitypub/database/base.py
index 9b6e89e..073387d 100644
--- a/activitypub/database/base.py
+++ b/activitypub/database/base.py
@@ -18,3 +18,10 @@ class Database():
         if attr not in self._tables:
             self._tables[attr] = self.Table(self, attr)
         return self._tables[attr]
+
+    def table_exists(self, table):
+        return table in self._tables
+
+    def build_table(self, name):
+        self._tables[name] = self.Table(self, name)
+
diff --git a/activitypub/database/listdb.py b/activitypub/database/listdb.py
index 3ee6db2..f685a13 100644
--- a/activitypub/database/listdb.py
+++ b/activitypub/database/listdb.py
@@ -170,7 +170,7 @@ class ListTable(Table):
         if i is not None:
             self.data[i] = dictionary
 
-    def drop(self):
+    def clear(self):
         self.data.clear()
 
     def sort(self, sort_key, sort_order):
@@ -381,7 +381,8 @@ class ListTable(Table):
         else:
             return len(self.data)
 
-    count_documents = count
+    def count_documents(self, query):
+        return self.count(query)
 
 class ListDatabase(Database):
     Table = ListTable
diff --git a/activitypub/database/mongodb.py b/activitypub/database/mongodb.py
index 2cc2221..a399335 100644
--- a/activitypub/database/mongodb.py
+++ b/activitypub/database/mongodb.py
@@ -45,6 +45,9 @@ class MongoTable(Table):
         else:
             self.__dict__[attr] = value
 
+    def clear(self):
+        self.collection.drop()
+
 class MongoDatabase(Database):
     Table = MongoTable
     def __init__(self, uri, db_name):
@@ -53,3 +56,6 @@ class MongoDatabase(Database):
         self.client = MongoClient(self.uri)
         self.db_name = db_name
         self.DB = self.client[self.db_name]
+
+    def table_exists(self, table):
+        return table in self.client.database_names()
diff --git a/tests/test_all.py b/tests/test_all.py
new file mode 100644
index 0000000..22b97af
--- /dev/null
+++ b/tests/test_all.py
@@ -0,0 +1,51 @@
+
+from activitypub.database import *
+from activitypub.manager import Manager
+
+def test_all():
+    for db in [
+            ListDatabase(),
+            SQLDatabase("sqlite://"),
+            SQLDatabase("sqlite:///sqlite.db"),
+            MongoDatabase("mongodb://localhost:27017", "dsblank_localhost:5005"),
+            RedisDatabase("redis://localhost:6379/0"),
+    ]:
+        print("Testing", db.__class__.__name__, "...")
+        manager = Manager(database=db)
+        if manager.database.table_exists("activities"):
+            manager.database.activities.clear()
+        else:
+            manager.database.build_table("activities")
+        manager.database.activities.clear()
+        manager.database.actors.clear()
+
+        assert manager.database.actors.count_documents(
+            {"$or": [{'id': 'https://example.com/alyssa'},
+                     {'id': 'https://example.com/alyssa'}]}) == 0
+        assert manager.database.actors.count_documents(
+            {"$or": [{'id': 'https://example.com/alyssa'},
+                     {'id': 'https://example.com/alyssa'}]}) == 0
+
+        p1 = manager.Person(id="alyssa")
+        p2 = manager.Person(id="brenda")
+        
+        manager.database.actors.insert_one(p1.to_dict())
+        manager.database.actors.insert_one(p2.to_dict())
+
+        assert manager.database.actors.count_documents(
+            {"$or": [{'id': 'https://example.com/alyssa'},
+                     {'id': 'https://example.com/brenda'}]}) == 2
+        assert len(list(manager.database.actors.find(
+            {"$or": [{'id': 'https://example.com/alyssa'},
+                     {'id': 'https://example.com/brenda'}]}))) == 2
+
+        assert manager.database.actors.count_documents(
+            {'id': 'https://example.com/alyssa'}) == 1
+        assert manager.database.actors.count_documents({}) == 2
+
+        ## Clean up
+        manager.database.activities.clear()
+        manager.database.actors.clear()
+
+if __name__ == "__main__":
+    test_all()