Add the Python 3.5 example.

python/examples/test_dual_write_new.py

@@ -0,0 +1,34 @@
+import os
+import tempfile
+
+#tag::test[]
+import unittest
+from pyspark.sql.types import Row
+from pyspark.testing.utils import assertDataFrameEqual
+from .dual_write import DualWriteExample
+
+
+class DualWriteTest(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.spark = SparkSession.builder.appName("Testing PySpark Example").getOrCreate()
+
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.spark.stop()
+
+    def test_always_passes(self):
+        self.assertTrue(True)
+
+    def test_actual_dual_write(self):
+        tempdir = tempfile.mkdtemp()
+        p1 = os.path.join(tempdir, "data1")
+        p2 = os.path.join(tempdir, "data2")
+        df = self.sqlCtx.createDataFrame([Row("timbit"), Row("farted")], ["names"])
+        combined = df.withColumn("times", current_timestamp())
+        DualWriteExample().do_write(combined, p1, p2)
+        df1 = self.sqlCtx.read.format("parquet").load(p1)
+        df2 = self.sqlCtx.read.format("parquet").load(p2)
+        assertDataFrameEqual(df2.select("times"), df1, 0.1)
+#end::test[]