add python test

Author: cloud-fan

python/pyspark/sql/tests.py

@@ -519,6 +519,13 @@ def test_access_nested_types(self):
         self.assertEqual("v", df.select(df.d["k"]).first()[0])
         self.assertEqual("v", df.select(df.d.getItem("k")).first()[0])
 
+    def test_field_accessor(self):
+        df = self.sc.parallelize([Row(l=[1], r=Row(a=1, b="b"), d={"k": "v"})]).toDF()
+        self.assertEqual(1, df.select(df.l[0]).first()[0])
+        self.assertEqual(1, df.select(df.r["a"]).first()[0])
+        self.assertEqual("b", df.select(df.r["b"]).first()[0])
+        self.assertEqual("v", df.select(df.d["k"]).first()[0])
+
     def test_infer_long_type(self):
         longrow = [Row(f1='a', f2=100000000000000)]
         df = self.sc.parallelize(longrow).toDF()