Respects ResultProxy.supports_sane_rowcount()

The check for matched rowcount when the alembic_version table is updated or
deleted from is now conditional based on whether or not the dialect
supports the concept of "rowcount" for UPDATE or DELETE rows matched.  Some
third party dialects do not support this concept.  Pull request courtesy Ke
Zhu.

Closes: #667
Pull-request: https://github.com/sqlalchemy/alembic/pull/667
Pull-request-sha: a0d45ed0f5de582314faae2210eeec881670488e

Change-Id: I09c9b540d8e21a94728085270eb20ba2273cbdb1

1 files changed, 37 insertions, 0 deletions

diff --git a/tests/test_version_table.py b/tests/test_version_table.py
index 34bdfab..1801346 100644
--- a/tests/test_version_table.py
+++ b/tests/test_version_table.py
@@ -262,6 +262,14 @@ class UpdateRevTest(TestBase):
             _up("x", "b"),
         )
 
+    def test_update_no_match_no_sane_rowcount(self):
+        self.updater.update_to_step(_up(None, "a", True))
+        self.updater.heads.add("x")
+        with mock.patch.object(
+            self.connection.dialect, "supports_sane_rowcount", False
+        ):
+            self.updater.update_to_step(_up("x", "b"))
+
     def test_update_multi_match(self):
         self.connection.execute(version_table.insert(), version_num="a")
         self.connection.execute(version_table.insert(), version_num="a")
@@ -275,6 +283,16 @@ class UpdateRevTest(TestBase):
             _up("a", "b"),
         )
 
+    def test_update_multi_match_no_sane_rowcount(self):
+        self.connection.execute(version_table.insert(), version_num="a")
+        self.connection.execute(version_table.insert(), version_num="a")
+
+        self.updater.heads.add("a")
+        with mock.patch.object(
+            self.connection.dialect, "supports_sane_rowcount", False
+        ):
+            self.updater.update_to_step(_up("a", "b"))
+
     def test_delete_no_match(self):
         self.updater.update_to_step(_up(None, "a", True))
 
@@ -287,6 +305,15 @@ class UpdateRevTest(TestBase):
             _down("x", None, True),
         )
 
+    def test_delete_no_matchno_sane_rowcount(self):
+        self.updater.update_to_step(_up(None, "a", True))
+
+        self.updater.heads.add("x")
+        with mock.patch.object(
+            self.connection.dialect, "supports_sane_rowcount", False
+        ):
+            self.updater.update_to_step(_down("x", None, True))
+
     def test_delete_multi_match(self):
         self.connection.execute(version_table.insert(), version_num="a")
         self.connection.execute(version_table.insert(), version_num="a")
@@ -299,3 +326,13 @@ class UpdateRevTest(TestBase):
             self.updater.update_to_step,
             _down("a", None, True),
         )
+
+    def test_delete_multi_match_no_sane_rowcount(self):
+        self.connection.execute(version_table.insert(), version_num="a")
+        self.connection.execute(version_table.insert(), version_num="a")
+
+        self.updater.heads.add("a")
+        with mock.patch.object(
+            self.connection.dialect, "supports_sane_rowcount", False
+        ):
+            self.updater.update_to_step(_down("a", None, True))