[GitHub] [spark] ueshin commented on a diff in pull request #42490: [SPARK-44749][PYTHON][FOLLOWUP][TESTS] Add more tests for named arguments in Python UDTF

["ueshin (via GitHub)" <gi...@apache.org>]

ueshin commented on code in PR #42490:
URL: https://github.com/apache/spark/pull/42490#discussion_r1293963530


##########
python/pyspark/sql/tests/test_udtf.py:
##########
@@ -1874,15 +1874,85 @@ def eval(self, **kwargs):
 
         for i, df in enumerate(
             [
-                self.spark.sql("SELECT * FROM test_udtf(a=>10, b=>'x')"),
-                self.spark.sql("SELECT * FROM test_udtf(b=>'x', a=>10)"),
+                self.spark.sql("SELECT * FROM test_udtf(a => 10, b => 'x')"),
+                self.spark.sql("SELECT * FROM test_udtf(b => 'x', a => 10)"),
                 TestUDTF(a=lit(10), b=lit("x")),
                 TestUDTF(b=lit("x"), a=lit(10)),
             ]
         ):
             with self.subTest(query_no=i):
                 assertDataFrameEqual(df, [Row(a=10, b="x")])
 
+    def test_udtf_with_named_arguments_lateral_join(self):
+        @udtf
+        class TestUDTF:
+            @staticmethod
+            def analyze(a, b):
+                return AnalyzeResult(StructType().add("a", a.data_type))
+
+            def eval(self, a, b):
+                yield a,
+
+        self.spark.udtf.register("test_udtf", TestUDTF)
+
+        # lateral join
+        for i, df in enumerate(
+            [
+                self.spark.sql(
+                    "SELECT f.* FROM "
+                    "VALUES (0, 'x'), (1, 'y') t(a, b), LATERAL test_udtf(a => a, b => b) f"
+                ),
+                self.spark.sql(
+                    "SELECT f.* FROM "
+                    "VALUES (0, 'x'), (1, 'y') t(a, b), LATERAL test_udtf(b => b, a => a) f"
+                ),
+            ]
+        ):
+            with self.subTest(query_no=i):
+                assertDataFrameEqual(df, [Row(a=0), Row(a=1)])
+
+    def test_udtf_with_named_arguments_and_defaults(self):
+        @udtf
+        class TestUDTF:
+            @staticmethod
+            def analyze(a, b=None):

Review Comment:
   Yes, if `b` here doesn't have a default value, it will raise an exception.
   
   Both `eval` and `analyze` will be called with the same argument list.
   So if `eval` takes `a`, `analyze` should also take `a`, if `eval` takes `a, b`, `analyze` should also take `a, b`, and so on.
   
   It can be `AnalyzeArgument` with the correct parameters, or take `**kwargs`.
   
   ```py
   def analyze(a, b=AnalyzeArgument(StringType(), None, False)):
   ```
   
   ```py
   def analyze(a, **kwargs):
   ```
   
   but taking `AnalyzeArgument` as default is not recommended if the `data_type` is a struct type, which could cause unexpected behavior similar to taking `[]` or `{}` as default.



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