Test data frames with pyspark (#135)

* Add tags to test_dual_write

* Add the Python 3.5 example.

* Fix up style and imports

* Remove excess newline

* Fix new test

python/examples/test_dual_write.py

@@ -1,6 +1,7 @@
 import os
 import tempfile
 
+# tag::test[]
 from sparktestingbase.sqltestcase import SQLTestCase
 from pyspark.sql.functions import current_timestamp
 from pyspark.sql.types import Row
@@ -21,3 +22,6 @@ def test_actual_dual_write(self):
         df1 = self.sqlCtx.read.format("parquet").load(p1)
         df2 = self.sqlCtx.read.format("parquet").load(p2)
         self.assertDataFrameEqual(df2.select("times"), df1, 0.1)
+
+
+# end::test[]

python/examples/test_dual_write_new.py

@@ -0,0 +1,39 @@
+import os
+import tempfile
+
+# tag::test[]
+import unittest
+from pyspark.sql import SparkSession
+from pyspark.sql.functions import current_timestamp
+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.spark.createDataFrame([Row("timbit"), Row("farted")], ["names"])
+        combined = df.withColumn("times", current_timestamp())
+        DualWriteExample().do_write(combined, p1, p2)
+        df1 = self.spark.read.format("parquet").load(p1)
+        df2 = self.spark.read.format("parquet").load(p2)
+        assertDataFrameEqual(df2.select("times"), df1, 0.1)
+
+
+# end::test[]

python/tox.ini

@@ -57,7 +57,7 @@ deps =
 [testenv:flake8]
 extras = tests
 skipsdist = True
-commands = flake8 --ignore=F403,E402,F401,F405,W503 examples
+commands = flake8 --ignore=F403,E402,F401,F405,W503,E265 examples
 allowlist_externals = flake8
 
 [testenv:mypy]