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# The ASF licenses this file to You under the Apache License, Version 2.0
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#    http://www.apache.org/licenses/LICENSE-2.0
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"""Unit tests for the PValue and PCollection classes."""

import unittest

from apache_beam.pvalue import AsSingleton
from apache_beam.pvalue import PValue
from apache_beam.testing.test_pipeline import TestPipeline


class PValueTest(unittest.TestCase):

  def test_pvalue_expected_arguments(self):
    pipeline = TestPipeline()
    value = PValue(pipeline)
    self.assertEqual(pipeline, value.pipeline)

  def test_assingleton_multi_element(self):
    with self.assertRaisesRegexp(
        ValueError,
        'PCollection of size 2 with more than one element accessed as a '
        'singleton view. First two elements encountered are \"1\", \"2\".'):
      AsSingleton._from_runtime_iterable([1, 2], {})


if __name__ == '__main__':
  unittest.main()
