Add backend.DatabaseError

This replaces the clunky "except tuple(exceptions.DatabaseErrors)" idiom

4 files changed, 8 insertions, 15 deletions

diff --git a/yoyo/backends.py b/yoyo/backends.py
index 2cb9e8f..f37f4df 100644
--- a/yoyo/backends.py
+++ b/yoyo/backends.py
@@ -119,6 +119,7 @@ class DatabaseBackend(object):
         self.migration_table = migration_table
         self.create_migrations_table()
         self.has_transactional_ddl = self._check_transactional_ddl()
+        self.DatabaseError = self.driver.DatabaseError
 
     def _load_driver_module(self):
         """
@@ -152,7 +153,7 @@ class DatabaseBackend(object):
         try:
             with self.transaction():
                 self.execute("DROP TABLE {}".format(table_name))
-        except tuple(exceptions.DatabaseErrors):
+        except self.DatabaseError:
             return True
         return False
 
@@ -225,7 +226,7 @@ class DatabaseBackend(object):
         try:
             with self.transaction():
                 self.execute(sql)
-        except tuple(exceptions.DatabaseErrors):
+        except self.DatabaseError:
             pass
 
     def _with_placeholders(self, sql):
diff --git a/yoyo/migrations.py b/yoyo/migrations.py
index 72fd1bf..fd12c4d 100755
--- a/yoyo/migrations.py
+++ b/yoyo/migrations.py
@@ -99,13 +99,13 @@ class Migration(object):
             try:
                 getattr(step, direction)(backend, force)
                 executed_steps.append(step)
-            except tuple(exceptions.DatabaseErrors):
+            except backend.DatabaseError:
                 backend.connection.rollback()
                 exc_info = sys.exc_info()
                 try:
                     for step in reversed(executed_steps):
                         getattr(step, reverse)(backend)
-                except tuple(exceptions.DatabaseErrors):
+                except backend.DatabaseError:
                     logger.exception(
                         'Database error when reversing %s of step', direction)
                 reraise(exc_info[0], exc_info[1], exc_info[2])
@@ -152,7 +152,7 @@ class TransactionWrapper(StepBase):
         with backend.transaction() as transaction:
             try:
                 getattr(self.step, direction)(backend, force)
-            except tuple(exceptions.DatabaseErrors):
+            except backend.DatabaseError:
                 if force or self.ignore_errors in (direction, 'all'):
                     logger.exception("Ignored error in %r", self.step)
                     transaction.rollback()
diff --git a/yoyo/tests/test_backends.py b/yoyo/tests/test_backends.py
index 0fc8050..2509ecc 100644
--- a/yoyo/tests/test_backends.py
+++ b/yoyo/tests/test_backends.py
@@ -1,7 +1,6 @@
 import pytest
 
 from yoyo import backends
-from yoyo import exceptions
 from yoyo.tests import get_test_backends
 
 
@@ -31,13 +30,11 @@ class TestTransactionHandling(object):
             assert rows == [('A',)]
 
     def test_it_rolls_back(self, backend):
-        try:
+        with pytest.raises(backend.DatabaseError):
             with backend.transaction():
                 backend.execute("INSERT INTO _yoyo_t values ('A')")
                 # Invalid SQL to produce an error
                 backend.execute("INSERT INTO nonexistant values ('A')")
-        except tuple(exceptions.DatabaseErrors):
-            pass
 
         with backend.transaction():
             rows = list(backend.execute("SELECT * FROM _yoyo_t").fetchall())
diff --git a/yoyo/tests/test_migrations.py b/yoyo/tests/test_migrations.py
index 6843b56..4a2c303 100644
--- a/yoyo/tests/test_migrations.py
+++ b/yoyo/tests/test_migrations.py
@@ -35,13 +35,8 @@ step("INSERT INTO _yoyo_test VALUES ('x', 'y')")
 def test_transaction_is_not_committed_on_error(tmpdir):
     backend = get_backend(dburi)
     migrations = read_migrations(tmpdir)
-    try:
+    with pytest.raises(backend.DatabaseError):
         backend.apply_migrations(migrations)
-    except tuple(exceptions.DatabaseErrors):
-        # Expected
-        pass
-    else:
-        raise AssertionError("Expected a DatabaseError")
     cursor = backend.cursor()
     cursor.execute("SELECT count(1) FROM _yoyo_test")
     assert cursor.fetchone() == (0,)