diff --git a/python/pyspark/sql/tests/test_dataframe.py b/python/pyspark/sql/tests/test_dataframe.py
index b5af00a4e7b78..a520c1a832fc4 100644
--- a/python/pyspark/sql/tests/test_dataframe.py
+++ b/python/pyspark/sql/tests/test_dataframe.py
@@ -506,14 +506,16 @@ def test_toDF_with_schema_string(self):
 
         # number of fields must match.
         self.assertRaisesRegex(
-            Exception, "FIELD_STRUCT_LENGTH_MISMATCH", lambda: rdd.toDF("key: int").collect()
+            Exception,
+            "FIELD_STRUCT_LENGTH_MISMATCH",
+            lambda: rdd.coalesce(1).toDF("key: int").collect(),
         )
 
         # field types mismatch will cause exception at runtime.
         self.assertRaisesRegex(
             Exception,
             "FIELD_DATA_TYPE_UNACCEPTABLE",
-            lambda: rdd.toDF("key: float, value: string").collect(),
+            lambda: rdd.coalesce(1).toDF("key: float, value: string").collect(),
         )
 
         # flat schema values will be wrapped into row.