Add unit tests for table comments

Signed-off-by: Jesse Whitehouse <[email protected]>

Author: Jesse Whitehouse

src/databricks/sqlalchemy/test_local/test_ddl.py

@@ -1,6 +1,13 @@
 import pytest
 from sqlalchemy import Column, MetaData, String, Table, create_engine
-from sqlalchemy.schema import CreateTable, DropColumnComment, SetColumnComment
+from sqlalchemy.schema import (
+    CreateTable,
+    DropColumnComment,
+    DropTableComment,
+    SetColumnComment,
+    SetTableComment,
+)
+
 
 class DDLTestBase:
     engine = create_engine(
@@ -12,7 +19,6 @@ def compile(self, stmt):
 
 
 class TestColumnCommentDDL(DDLTestBase):
-
     @pytest.fixture
     def metadata(self) -> MetaData:
         """Assemble a metadata object with one table containing one column."""
@@ -48,5 +54,42 @@ def test_alter_table_drop_column_comment(self, column):
         output = self.compile(stmt)
         assert output == "ALTER TABLE foobar ALTER COLUMN foo COMMENT ''"
 
+
 class TestTableCommentDDL(DDLTestBase):
-    pass
+    @pytest.fixture
+    def metadata(self) -> MetaData:
+        """Assemble a metadata object with one table containing one column."""
+        metadata = MetaData()
+
+        col1 = Column("foo", String)
+        col2 = Column("foo", String)
+        tbl_w_comment = Table("martin", metadata, col1, comment="foobar")
+        tbl_wo_comment = Table("prs", metadata, col2)
+
+        return metadata
+
+    @pytest.fixture
+    def table_with_comment(self, metadata) -> Table:
+        return metadata.tables.get("martin")
+
+    @pytest.fixture
+    def table_without_comment(self, metadata) -> Table:
+        return metadata.tables.get("prs")
+
+    def test_create_table_with_comment(self, table_with_comment):
+        stmt = CreateTable(table_with_comment)
+        output = self.compile(stmt)
+        assert "USING DELTA COMMENT 'foobar'" in output
+
+    def test_alter_table_add_comment(self, table_without_comment: Table):
+        table_without_comment.comment = "wireless mechanical keyboard"
+        stmt = SetTableComment(table_without_comment)
+        output = self.compile(stmt)
+
+        assert output == "COMMENT ON TABLE prs IS 'wireless mechanical keyboard'"
+
+    def test_alter_table_drop_comment(self, table_with_comment):
+        """The syntax for COMMENT ON is here: https://docs.databricks.com/en/sql/language-manual/sql-ref-syntax-ddl-comment.html"""
+        stmt = DropTableComment(table_with_comment)
+        output = self.compile(stmt)
+        assert output == "COMMENT ON TABLE martin IS NULL"