tests/

Author: Chris Jarrett

tests/integration/test_join.py

@@ -107,6 +107,27 @@ def test_join_left_anti(c):
     assert_eq(return_df, expected_df, check_index=False)
 
 
+def test_join_left_semi(c):
+    return_df = c.sql(
+        """
+    SELECT lhs.user_id, lhs.c
+    FROM user_table_2 AS lhs
+    LEFT SEMI JOIN user_table_1 AS rhs
+    ON lhs.user_id = rhs.user_id
+    """
+    )
+    expected_df = pd.DataFrame(
+        {
+            # That is strange. Unfortunately, it seems dask fills in the
+            # missing rows with NaN, not with NA...
+            "user_id": [1, 1, 2],
+            "c": [1, 2, 3],
+        }
+    )
+
+    assert_eq(return_df, expected_df, check_index=False)
+
+
 def test_join_right(c):
     return_df = c.sql(
         """