fix(api): ensure memtable schema and columns match

ibis/expr/api.py

@@ -408,6 +408,12 @@ def memtable(
             "passing `columns` and schema` is ambiguous; "
             "pass one or the other but not both"
         )
+
+    if schema is not None:
+        import ibis
+
+        schema = ibis.schema(schema)
+
     return _memtable(data, name=name, schema=schema, columns=columns)
 
 

ibis/expr/tests/test_api.py

@@ -143,6 +143,15 @@
         ibis.memtable(df)
 
 
+def test_memtable_column_names_match_schema():
+    pd = pytest.importorskip("pandas")
+
+    df = pd.DataFrame([[1, 2], [3, 4]])
+    schema = {"a": "int64", "b": "int64"}
+    t = ibis.memtable(df, schema=schema)
+    assert t.op().data.to_frame().columns.tolist() == ["a", "b"]
+
+
 @pytest.mark.parametrize(
     "op",
     [