fix spark tests

Author: evertlammerts

duckdb/experimental/spark/sql/type_utils.py

@@ -19,6 +19,7 @@
     IntegerType,
     LongType,
     MapType,
+    NullType,
     ShortType,
     StringType,
     StructField,
@@ -42,6 +43,7 @@
 )
 
 _sqltype_to_spark_class = {
+    "null": NullType,
     "boolean": BooleanType,
     "utinyint": UnsignedByteType,
     "tinyint": ByteType,

tests/fast/test_case_alias.py

@@ -15,20 +15,22 @@ def test_case_alias(self, duckdb_cursor):
         assert r1["CoL2"][0] == 1.05
         assert r1["CoL2"][1] == 17
 
+        # An explicit column reference takes its output name from the casing as written in the query (COL2),
+        # unlike `select *` above which preserves the source column's casing (CoL2).
         r2 = con.from_df(df).query("df", "select COL1, COL2 from df").df()
         assert r2["COL1"][0] == "val1"
         assert r2["COL1"][1] == "val3"
-        assert r2["CoL2"][0] == 1.05
-        assert r2["CoL2"][1] == 17
+        assert r2["COL2"][0] == 1.05
+        assert r2["COL2"][1] == 17
 
         r3 = con.from_df(df).query("df", "select COL1, COL2 from df ORDER BY COL1").df()
         assert r3["COL1"][0] == "val1"
         assert r3["COL1"][1] == "val3"
-        assert r3["CoL2"][0] == 1.05
-        assert r3["CoL2"][1] == 17
+        assert r3["COL2"][0] == 1.05
+        assert r3["COL2"][1] == 17
 
         r4 = con.from_df(df).query("df", "select COL1, COL2 from df GROUP BY COL1, COL2 ORDER BY COL1").df()
         assert r4["COL1"][0] == "val1"
         assert r4["COL1"][1] == "val3"
-        assert r4["CoL2"][0] == 1.05
-        assert r4["CoL2"][1] == 17
+        assert r4["COL2"][0] == 1.05
+        assert r4["COL2"][1] == 17