add some debug checks in test case and remove an extra line (#37237)

Author: derrickaw

sdks/python/apache_beam/dataframe/io.py

@@ -793,7 +793,6 @@ def __init__(
     if format == 'csv':
       kwargs['filename_column'] = filename_column
     self._reader = globals()['read_%s' % format](*args, **kwargs)
-    self._reader = globals()['read_%s' % format](*args, **kwargs)
     self._include_indexes = include_indexes
     self._objects_as_strings = objects_as_strings
     self._filename_column = filename_column

sdks/python/apache_beam/yaml/yaml_transform_test.py

@@ -34,6 +34,8 @@
 except ImportError:
   jsonschema = None
 
+_LOGGER = logging.getLogger(__name__)
+
 
 class CreateTimestamped(beam.PTransform):
   _yaml_requires_inputs = False
@@ -244,6 +246,10 @@ def test_csv_to_json(self):
       input = os.path.join(tmpdir, 'input.csv')
       output = os.path.join(tmpdir, 'output.json')
       data.to_csv(input, index=False)
+      with open(input, 'r') as f:
+        lines = f.readlines()
+      _LOGGER.debug("input.csv has these {lines} lines.")
+      self.assertEqual(len(lines), len(data) + 1)  # +1 for header
 
       with beam.Pipeline() as p:
         result = p | YamlTransform(
@@ -256,9 +262,11 @@ def test_csv_to_json(self):
               - type: WriteToJson
                 config:
                     path: %s
-                num_shards: 1
+                    num_shards: 1
+              - type: LogForTesting
             ''' % (repr(input), repr(output)))
-
+      all_output = list(glob.glob(output + "*"))
+      self.assertEqual(len(all_output), 1)
       output_shard = list(glob.glob(output + "*"))[0]
       result = pd.read_json(
           output_shard, orient='records',