sdks/python/apache_beam/coders/observable_test.py

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"""Tests for the Observable mixin class."""
# pytype: skip-file

import logging
import unittest
from typing import Optional

from apache_beam.coders import observable


class ObservableMixinTest(unittest.TestCase):
  observed_count = 0
  observed_sum = 0
  observed_keys: list[Optional[str]] = []

  def observer(self, value, key=None):
    self.observed_count += 1
    self.observed_sum += value
    self.observed_keys.append(key)

  def test_observable(self):
    class Watched(observable.ObservableMixin):
      def __iter__(self):
        for i in (1, 4, 3):
          self.notify_observers(i, key='a%d' % i)
          yield i

    watched = Watched()
    watched.register_observer(lambda v, key: self.observer(v, key=key))
    for _ in watched:
      pass

    self.assertEqual(3, self.observed_count)
    self.assertEqual(8, self.observed_sum)
    self.assertEqual(['a1', 'a3', 'a4'], sorted(self.observed_keys))


if __name__ == '__main__':
  logging.getLogger().setLevel(logging.INFO)
  unittest.main()