added a test for setting a Varchar column's length via a MigrationManager

Author: dantownsend

tests/apps/migrations/auto/test_migration_manager.py

@@ -516,11 +516,44 @@ def test_alter_column_set_type(self):
 
         asyncio.run(manager.run())
 
-        column_type_str = self.get_postgres_column_type_str(
+        column_type_str = self.get_postgres_column_type(
             tablename="manager", column_name="name"
         )
         self.assertEqual(column_type_str, "TEXT")
 
+    @postgres_only
+    def test_alter_column_set_length(self):
+        """
+        Test altering a Varchar column's length with MigrationManager.
+        """
+        manager = MigrationManager()
+
+        manager.alter_column(
+            table_class_name="Manager",
+            tablename="manager",
+            column_name="name",
+            params={"length": 500},
+            old_params={"length": 200},
+            column_class=Text,
+            old_column_class=Varchar,
+        )
+
+        asyncio.run(manager.run())
+        self.assertEqual(
+            self.get_postgres_varchar_length(
+                tablename="manager", column_name="name"
+            ),
+            500,
+        )
+
+        asyncio.run(manager.run_backwards())
+        self.assertEqual(
+            self.get_postgres_varchar_length(
+                tablename="manager", column_name="name"
+            ),
+            200,
+        )
+
     @postgres_only
     @patch.object(BaseMigrationManager, "get_migration_managers")
     def test_drop_table(self, get_migration_managers: MagicMock):

tests/base.py

@@ -73,7 +73,7 @@ def get_postgres_column_definition(
         response = self.run_sync(query)
         return response[0]
 
-    def get_postgres_column_type_str(
+    def get_postgres_column_type(
         self, tablename: str, column_name: str
     ) -> str:
         """
@@ -94,6 +94,14 @@ def get_postgres_is_nullable(self, tablename, column_name: str) -> bool:
             == "YES"
         )
 
+    def get_postgres_varchar_length(self, tablename, column_name: str) -> int:
+        """
+        Fetches whether the column is defined as nullable, from the database.
+        """
+        return self.get_postgres_column_definition(
+            tablename=tablename, column_name=column_name
+        )["character_maximum_length"]
+
     ###########################################################################
 
     def create_tables(self):

tests/table/test_alter.py

@@ -152,7 +152,7 @@ def test_integer_to_bigint(self):
         alter_query.run_sync()
 
         self.assertEqual(
-            self.get_postgres_column_type_str(
+            self.get_postgres_column_type(
                 tablename="band", column_name="popularity"
             ),
             "BIGINT",
@@ -175,7 +175,7 @@ def test_integer_to_varchar(self):
         alter_query.run_sync()
 
         self.assertEqual(
-            self.get_postgres_column_type_str(
+            self.get_postgres_column_type(
                 tablename="band", column_name="popularity"
             ),
             "CHARACTER VARYING",