add test

Author: szalai1

python/pyspark/sql/tests.py

@@ -188,6 +188,10 @@ def test_empty_row(self):
         row = Row()
         self.assertEqual(len(row), 0)
 
+    def test_struct_field_type_name(self):
+        struct_field = StructField()
+        self.assertRaises(typeError('StructField does not have typename. You can use self.dataType.simpleString() instead.'), struct_field.typeName)
+
 
 class SQLTests(ReusedPySparkTestCase):
 

python/pyspark/sql/types.py

@@ -439,7 +439,7 @@ def fromInternal(self, obj):
         return self.dataType.fromInternal(obj)
 
     def typeName(self):
-        raise TypeError('StructField does not have typename')
+        raise TypeError('StructField does not have typename. You can use self.dataType.simpleString() instead.')
 
 
 class StructType(DataType):