Enabled parallel testing by default in runtests.py.

django/db/backends/base/features.py

@@ -212,6 +212,10 @@ class BaseDatabaseFeatures(object):
     # every expression is null?
     greatest_least_ignores_nulls = False
 
+    # Can the backend clone databases for parallel test execution?
+    # Defaults to False to allow third-party backends to opt-in.
+    can_clone_databases = False
+
     def __init__(self, connection):
         self.connection = connection
 

django/db/backends/mysql/features.py

@@ -31,6 +31,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     can_release_savepoints = True
     atomic_transactions = False
     supports_column_check_constraints = False
+    can_clone_databases = True
 
     @cached_property
     def _mysql_storage_engine(self):

django/db/backends/postgresql/features.py

@@ -28,3 +28,4 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     has_case_insensitive_like = False
     requires_sqlparse_for_splitting = False
     greatest_least_ignores_nulls = True
+    can_clone_databases = True

django/db/backends/sqlite3/features.py

@@ -37,6 +37,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     can_rollback_ddl = True
     supports_paramstyle_pyformat = False
     supports_sequence_reset = False
+    can_clone_databases = True
 
     @cached_property
     def uses_savepoints(self):