Adds a unit test for quantization offset heuristic with noisy distributions.

PiperOrigin-RevId: 449798025
Change-Id: I18bc0b4f22a413bf7ceba8175425e5679cc0a1a2

Author: Johannes Ballé

tensorflow_compression/python/distributions/uniform_noise_test.py

@@ -75,6 +75,10 @@ def test_stats_throw_error(self):
     with self.assertRaises(NotImplementedError):
       dist.survival_function(.5)
 
+  def test_quantizes_to_mode_decimal_part(self):
+    dist = self.dist_cls(loc=-3.75, scale=1.)
+    self.assertEqual(helpers.quantization_offset(dist), .25)
+
 
 class NoisyNormalTest(LocationScaleTest, tf.test.TestCase):