Pytest for test_videoapi.py and test_video_reader.py (#4233)

* test_video_reader pytest refactoring

* pytest refactoring of test_videoapi.py

* test_video_reader pytest refactoring

* pytest refactoring of test_videoapi.py

* using pytest.approx for test_video_reader.py

* using pytest.approx for test_videoapi.py

* Fixing minor comments

* linting fixes

* minor comments
Co-authored-by: Vincent Moens <vmoens@fb.com>

test/common_utils.py

@@ -3,6 +3,7 @@ import shutil
 import tempfile
 import contextlib
 import unittest
+import pytest
 import argparse
 import sys
 import torch
@@ -20,7 +21,7 @@ from PIL import Image
 
 IS_PY39 = sys.version_info.major == 3 and sys.version_info.minor == 9
 PY39_SEGFAULT_SKIP_MSG = "Segmentation fault with Python 3.9, see https://github.com/pytorch/vision/issues/3367"
-PY39_SKIP = unittest.skipIf(IS_PY39, PY39_SEGFAULT_SKIP_MSG)
+PY39_SKIP = pytest.mark.skipif(IS_PY39, reason=PY39_SEGFAULT_SKIP_MSG)
 IN_CIRCLE_CI = os.getenv("CIRCLECI", False) == 'true'
 IN_RE_WORKER = os.environ.get("INSIDE_RE_WORKER") is not None
 IN_FBCODE = os.environ.get("IN_FBCODE_TORCHVISION") == "1"
@@ -83,129 +84,6 @@ def is_iterable(obj):
         return False
 
 
-# adapted from TestCase in torch/test/common_utils to accept non-string
-# inputs and set maximum binary size
-class TestCase(unittest.TestCase):
-    precision = 1e-5
-
-    def assertEqual(self, x, y, prec=None, message='', allow_inf=False):
-        """
-        This is copied from pytorch/test/common_utils.py's TestCase.assertEqual
-        """
-        if isinstance(prec, str) and message == '':
-            message = prec
-            prec = None
-        if prec is None:
-            prec = self.precision
-
-        if isinstance(x, torch.Tensor) and isinstance(y, Number):
-            self.assertEqual(x.item(), y, prec=prec, message=message,
-                             allow_inf=allow_inf)
-        elif isinstance(y, torch.Tensor) and isinstance(x, Number):
-            self.assertEqual(x, y.item(), prec=prec, message=message,
-                             allow_inf=allow_inf)
-        elif isinstance(x, torch.Tensor) and isinstance(y, torch.Tensor):
-            def assertTensorsEqual(a, b):
-                super(TestCase, self).assertEqual(a.size(), b.size(), message)
-                if a.numel() > 0:
-                    if (a.device.type == 'cpu' and (a.dtype == torch.float16 or a.dtype == torch.bfloat16)):
-                        # CPU half and bfloat16 tensors don't have the methods we need below
-                        a = a.to(torch.float32)
-                    b = b.to(a)
-
-                    if (a.dtype == torch.bool) != (b.dtype == torch.bool):
-                        raise TypeError("Was expecting both tensors to be bool type.")
-                    else:
-                        if a.dtype == torch.bool and b.dtype == torch.bool:
-                            # we want to respect precision but as bool doesn't support substraction,
-                            # boolean tensor has to be converted to int
-                            a = a.to(torch.int)
-                            b = b.to(torch.int)
-
-                        diff = a - b
-                        if a.is_floating_point():
-                            # check that NaNs are in the same locations
-                            nan_mask = torch.isnan(a)
-                            self.assertTrue(torch.equal(nan_mask, torch.isnan(b)), message)
-                            diff[nan_mask] = 0
-                            # inf check if allow_inf=True
-                            if allow_inf:
-                                inf_mask = torch.isinf(a)
-                                inf_sign = inf_mask.sign()
-                                self.assertTrue(torch.equal(inf_sign, torch.isinf(b).sign()), message)
-                                diff[inf_mask] = 0
-                        # TODO: implement abs on CharTensor (int8)
-                        if diff.is_signed() and diff.dtype != torch.int8:
-                            diff = diff.abs()
-                        max_err = diff.max()
-                        tolerance = prec + prec * abs(a.max())
-                        self.assertLessEqual(max_err, tolerance, message)
-            super(TestCase, self).assertEqual(x.is_sparse, y.is_sparse, message)
-            super(TestCase, self).assertEqual(x.is_quantized, y.is_quantized, message)
-            if x.is_sparse:
-                x = self.safeCoalesce(x)
-                y = self.safeCoalesce(y)
-                assertTensorsEqual(x._indices(), y._indices())
-                assertTensorsEqual(x._values(), y._values())
-            elif x.is_quantized and y.is_quantized:
-                self.assertEqual(x.qscheme(), y.qscheme(), prec=prec,
-                                 message=message, allow_inf=allow_inf)
-                if x.qscheme() == torch.per_tensor_affine:
-                    self.assertEqual(x.q_scale(), y.q_scale(), prec=prec,
-                                     message=message, allow_inf=allow_inf)
-                    self.assertEqual(x.q_zero_point(), y.q_zero_point(),
-                                     prec=prec, message=message,
-                                     allow_inf=allow_inf)
-                elif x.qscheme() == torch.per_channel_affine:
-                    self.assertEqual(x.q_per_channel_scales(), y.q_per_channel_scales(), prec=prec,
-                                     message=message, allow_inf=allow_inf)
-                    self.assertEqual(x.q_per_channel_zero_points(), y.q_per_channel_zero_points(),
-                                     prec=prec, message=message,
-                                     allow_inf=allow_inf)
-                    self.assertEqual(x.q_per_channel_axis(), y.q_per_channel_axis(),
-                                     prec=prec, message=message)
-                self.assertEqual(x.dtype, y.dtype)
-                self.assertEqual(x.int_repr().to(torch.int32),
-                                 y.int_repr().to(torch.int32), prec=prec,
-                                 message=message, allow_inf=allow_inf)
-            else:
-                assertTensorsEqual(x, y)
-        elif isinstance(x, string_classes) and isinstance(y, string_classes):
-            super(TestCase, self).assertEqual(x, y, message)
-        elif type(x) == set and type(y) == set:
-            super(TestCase, self).assertEqual(x, y, message)
-        elif isinstance(x, dict) and isinstance(y, dict):
-            if isinstance(x, OrderedDict) and isinstance(y, OrderedDict):
-                self.assertEqual(x.items(), y.items(), prec=prec,
-                                 message=message, allow_inf=allow_inf)
-            else:
-                self.assertEqual(set(x.keys()), set(y.keys()), prec=prec,
-                                 message=message, allow_inf=allow_inf)
-                key_list = list(x.keys())
-                self.assertEqual([x[k] for k in key_list],
-                                 [y[k] for k in key_list],
-                                 prec=prec, message=message,
-                                 allow_inf=allow_inf)
-        elif is_iterable(x) and is_iterable(y):
-            super(TestCase, self).assertEqual(len(x), len(y), message)
-            for x_, y_ in zip(x, y):
-                self.assertEqual(x_, y_, prec=prec, message=message,
-                                 allow_inf=allow_inf)
-        elif isinstance(x, bool) and isinstance(y, bool):
-            super(TestCase, self).assertEqual(x, y, message)
-        elif isinstance(x, Number) and isinstance(y, Number):
-            inf = float("inf")
-            if abs(x) == inf or abs(y) == inf:
-                if allow_inf:
-                    super(TestCase, self).assertEqual(x, y, message)
-                else:
-                    self.fail("Expected finite numeric values - x={}, y={}".format(x, y))
-                return
-            super(TestCase, self).assertLessEqual(abs(x - y), prec, message)
-        else:
-            super(TestCase, self).assertEqual(x, y, message)
-
-
 @contextlib.contextmanager
 def freeze_rng_state():
     rng_state = torch.get_rng_state()

test/test_video_reader.py

@@ -2,7 +2,8 @@ import collections
 import itertools
 import math
 import os
-import unittest
+import pytest
+from pytest import approx
 from fractions import Fraction
 
 import numpy as np
@@ -268,9 +269,9 @@ def _get_video_tensor(video_dir, video_file):
     return full_path, video_tensor
 
 
-@unittest.skipIf(av is None, "PyAV unavailable")
-@unittest.skipIf(_HAS_VIDEO_OPT is False, "Didn't compile with ffmpeg")
-class TestVideoReader(unittest.TestCase):
+@pytest.mark.skipif(av is None, reason="PyAV unavailable")
+@pytest.mark.skipif(_HAS_VIDEO_OPT is False, reason="Didn't compile with ffmpeg")
+class TestVideoReader:
     def check_separate_decoding_result(self, tv_result, config):
         """check the decoding results from TorchVision decoder
         """
@@ -282,45 +283,46 @@ class TestVideoReader(unittest.TestCase):
         video_duration = vduration.item() * Fraction(
             vtimebase[0].item(), vtimebase[1].item()
         )
-        self.assertAlmostEqual(video_duration, config.duration, delta=0.5)
+        assert video_duration == approx(config.duration, abs=0.5)
+
+        assert vfps.item() == approx(config.video_fps, abs=0.5)
 
-        self.assertAlmostEqual(vfps.item(), config.video_fps, delta=0.5)
         if asample_rate.numel() > 0:
-            self.assertEqual(asample_rate.item(), config.audio_sample_rate)
+            assert asample_rate.item() == config.audio_sample_rate
             audio_duration = aduration.item() * Fraction(
                 atimebase[0].item(), atimebase[1].item()
             )
-            self.assertAlmostEqual(audio_duration, config.duration, delta=0.5)
+            assert audio_duration == approx(config.duration, abs=0.5)
 
         # check if pts of video frames are sorted in ascending order
         for i in range(len(vframe_pts) - 1):
-            self.assertEqual(vframe_pts[i] < vframe_pts[i + 1], True)
+            assert vframe_pts[i] < vframe_pts[i + 1]
 
         if len(aframe_pts) > 1:
             # check if pts of audio frames are sorted in ascending order
             for i in range(len(aframe_pts) - 1):
-                self.assertEqual(aframe_pts[i] < aframe_pts[i + 1], True)
+                assert aframe_pts[i] < aframe_pts[i + 1]
 
     def check_probe_result(self, result, config):
         vtimebase, vfps, vduration, atimebase, asample_rate, aduration = result
         video_duration = vduration.item() * Fraction(
             vtimebase[0].item(), vtimebase[1].item()
         )
-        self.assertAlmostEqual(video_duration, config.duration, delta=0.5)
-        self.assertAlmostEqual(vfps.item(), config.video_fps, delta=0.5)
+        assert video_duration == approx(config.duration, abs=0.5)
+        assert vfps.item() == approx(config.video_fps, abs=0.5)
         if asample_rate.numel() > 0:
-            self.assertEqual(asample_rate.item(), config.audio_sample_rate)
+            assert asample_rate.item() == config.audio_sample_rate
             audio_duration = aduration.item() * Fraction(
                 atimebase[0].item(), atimebase[1].item()
             )
-            self.assertAlmostEqual(audio_duration, config.duration, delta=0.5)
+            assert audio_duration == approx(config.duration, abs=0.5)
 
     def check_meta_result(self, result, config):
-        self.assertAlmostEqual(result.video_duration, config.duration, delta=0.5)
-        self.assertAlmostEqual(result.video_fps, config.video_fps, delta=0.5)
+        assert result.video_duration == approx(config.duration, abs=0.5)
+        assert result.video_fps == approx(config.video_fps, abs=0.5)
         if result.has_audio > 0:
-            self.assertEqual(result.audio_sample_rate, config.audio_sample_rate)
-            self.assertAlmostEqual(result.audio_duration, config.duration, delta=0.5)
+            assert result.audio_sample_rate == config.audio_sample_rate
+            assert result.audio_duration == approx(config.duration, abs=0.5)
 
     def compare_decoding_result(self, tv_result, ref_result, config=all_check_config):
         """
@@ -350,12 +352,12 @@ class TestVideoReader(unittest.TestCase):
             mean_delta = torch.mean(
                 torch.abs(vframes.float() - ref_result.vframes.float())
             )
-            self.assertAlmostEqual(mean_delta, 0, delta=8.0)
+            assert mean_delta == approx(0.0, abs=8.0)
 
         mean_delta = torch.mean(
             torch.abs(vframe_pts.float() - ref_result.vframe_pts.float())
         )
-        self.assertAlmostEqual(mean_delta, 0, delta=1.0)
+        assert mean_delta == approx(0.0, abs=1.0)
 
         assert_equal(vtimebase, ref_result.vtimebase)
 
@@ -378,12 +380,12 @@ class TestVideoReader(unittest.TestCase):
 
             assert_equal(atimebase, ref_result.atimebase)
 
-    @unittest.skip(
-        "This stress test will iteratively decode the same set of videos."
-        "It helps to detect memory leak but it takes lots of time to run."
-        "By default, it is disabled"
-    )
     def test_stress_test_read_video_from_file(self):
+        pytest.skip(
+            "This stress test will iteratively decode the same set of videos."
+            "It helps to detect memory leak but it takes lots of time to run."
+            "By default, it is disabled"
+        )
         num_iter = 10000
         # video related
         width, height, min_dimension, max_dimension = 0, 0, 0, 0
@@ -513,18 +515,18 @@ class TestVideoReader(unittest.TestCase):
                         tv_result
                     )
 
-                self.assertEqual(vframes.numel() > 0, readVideoStream)
-                self.assertEqual(vframe_pts.numel() > 0, readVideoStream)
-                self.assertEqual(vtimebase.numel() > 0, readVideoStream)
-                self.assertEqual(vfps.numel() > 0, readVideoStream)
+                assert (vframes.numel() > 0) is bool(readVideoStream)
+                assert (vframe_pts.numel() > 0) is bool(readVideoStream)
+                assert (vtimebase.numel() > 0) is bool(readVideoStream)
+                assert (vfps.numel() > 0) is bool(readVideoStream)
 
                 expect_audio_data = (
                     readAudioStream == 1 and config.audio_sample_rate is not None
                 )
-                self.assertEqual(aframes.numel() > 0, expect_audio_data)
-                self.assertEqual(aframe_pts.numel() > 0, expect_audio_data)
-                self.assertEqual(atimebase.numel() > 0, expect_audio_data)
-                self.assertEqual(asample_rate.numel() > 0, expect_audio_data)
+                assert (aframes.numel() > 0) is bool(expect_audio_data)
+                assert (aframe_pts.numel() > 0) is bool(expect_audio_data)
+                assert (atimebase.numel() > 0) is bool(expect_audio_data)
+                assert (asample_rate.numel() > 0) is bool(expect_audio_data)
 
     def test_read_video_from_file_rescale_min_dimension(self):
         """
@@ -564,9 +566,7 @@ class TestVideoReader(unittest.TestCase):
                 audio_timebase_num,
                 audio_timebase_den,
             )
-            self.assertEqual(
-                min_dimension, min(tv_result[0].size(1), tv_result[0].size(2))
-            )
+            assert min_dimension == min(tv_result[0].size(1), tv_result[0].size(2))
 
     def test_read_video_from_file_rescale_max_dimension(self):
         """
@@ -606,9 +606,7 @@ class TestVideoReader(unittest.TestCase):
                 audio_timebase_num,
                 audio_timebase_den,
             )
-            self.assertEqual(
-                max_dimension, max(tv_result[0].size(1), tv_result[0].size(2))
-            )
+            assert max_dimension == max(tv_result[0].size(1), tv_result[0].size(2))
 
     def test_read_video_from_file_rescale_both_min_max_dimension(self):
         """
@@ -648,12 +646,8 @@ class TestVideoReader(unittest.TestCase):
                 audio_timebase_num,
                 audio_timebase_den,
             )
-            self.assertEqual(
-                min_dimension, min(tv_result[0].size(1), tv_result[0].size(2))
-            )
-            self.assertEqual(
-                max_dimension, max(tv_result[0].size(1), tv_result[0].size(2))
-            )
+            assert min_dimension == min(tv_result[0].size(1), tv_result[0].size(2))
+            assert max_dimension == max(tv_result[0].size(1), tv_result[0].size(2))
 
     def test_read_video_from_file_rescale_width(self):
         """
@@ -693,7 +687,7 @@ class TestVideoReader(unittest.TestCase):
                 audio_timebase_num,
                 audio_timebase_den,
             )
-            self.assertEqual(tv_result[0].size(2), width)
+            assert tv_result[0].size(2) == width
 
     def test_read_video_from_file_rescale_height(self):
         """
@@ -733,7 +727,7 @@ class TestVideoReader(unittest.TestCase):
                 audio_timebase_num,
                 audio_timebase_den,
             )
-            self.assertEqual(tv_result[0].size(1), height)
+            assert tv_result[0].size(1) == height
 
     def test_read_video_from_file_rescale_width_and_height(self):
         """
@@ -773,8 +767,8 @@ class TestVideoReader(unittest.TestCase):
                 audio_timebase_num,
                 audio_timebase_den,
             )
-            self.assertEqual(tv_result[0].size(1), height)
-            self.assertEqual(tv_result[0].size(2), width)
+            assert tv_result[0].size(1) == height
+            assert tv_result[0].size(2) == width
 
     @PY39_SKIP
     def test_read_video_from_file_audio_resampling(self):
@@ -822,19 +816,15 @@ class TestVideoReader(unittest.TestCase):
                         tv_result
                     )
                 if aframes.numel() > 0:
-                    self.assertEqual(samples, asample_rate.item())
-                    self.assertEqual(1, aframes.size(1))
+                    assert samples == asample_rate.item()
+                    assert 1 == aframes.size(1)
                     # when audio stream is found
                     duration = (
                         float(aframe_pts[-1])
                         * float(atimebase[0])
                         / float(atimebase[1])
                     )
-                    self.assertAlmostEqual(
-                        aframes.size(0),
-                        int(duration * asample_rate.item()),
-                        delta=0.1 * asample_rate.item(),
-                    )
+                    assert aframes.size(0) == approx(int(duration * asample_rate.item()), abs=0.1 * asample_rate.item())
 
     @PY39_SKIP
     def test_compare_read_video_from_memory_and_file(self):
@@ -989,7 +979,7 @@ class TestVideoReader(unittest.TestCase):
                 audio_timebase_num,
                 audio_timebase_den,
             )
-            self.assertAlmostEqual(config.video_fps, tv_result[3].item(), delta=0.01)
+            assert abs(config.video_fps - tv_result[3].item()) < 0.01
 
             # pass 2: decode all frames to get PTS only using cpp decoder
             tv_result_pts_only = torch.ops.video_reader.read_video_from_memory(
@@ -1014,8 +1004,8 @@ class TestVideoReader(unittest.TestCase):
                 audio_timebase_den,
             )
 
-            self.assertEqual(tv_result_pts_only[0].numel(), 0)
-            self.assertEqual(tv_result_pts_only[5].numel(), 0)
+            assert not tv_result_pts_only[0].numel()
+            assert not tv_result_pts_only[5].numel()
             self.compare_decoding_result(tv_result, tv_result_pts_only)
 
     @PY39_SKIP
@@ -1061,7 +1051,7 @@ class TestVideoReader(unittest.TestCase):
                 aframes, aframe_pts, atimebase, asample_rate, aduration = (
                     tv_result
                 )
-            self.assertAlmostEqual(config.video_fps, vfps.item(), delta=0.01)
+            assert abs(config.video_fps - vfps.item()) < 0.01
 
             for num_frames in [4, 8, 16, 32, 64, 128]:
                 start_pts_ind_max = vframe_pts.size(0) - num_frames
@@ -1160,7 +1150,7 @@ class TestVideoReader(unittest.TestCase):
                     audio_end_pts,
                 )
 
-                self.assertEqual(tv_result[0].size(0), num_frames)
+                assert tv_result[0].size(0) == num_frames
                 if pyav_result.vframes.size(0) == num_frames:
                     # if PyAv decodes a different number of video frames, skip
                     # comparing the decoding results between Torchvision video reader
@@ -1187,7 +1177,7 @@ class TestVideoReader(unittest.TestCase):
 
     def test_probe_video_from_memory_script(self):
         scripted_fun = torch.jit.script(io._probe_video_from_memory)
-        self.assertIsNotNone(scripted_fun)
+        assert scripted_fun is not None
 
         for test_video, config in test_videos.items():
             full_path, video_tensor = _get_video_tensor(VIDEO_DIR, test_video)
@@ -1209,7 +1199,7 @@ class TestVideoReader(unittest.TestCase):
         audio_timebase_num, audio_timebase_den = 0, 1
 
         scripted_fun = torch.jit.script(io._read_video_from_memory)
-        self.assertIsNotNone(scripted_fun)
+        assert scripted_fun is not None
 
         for test_video, _config in test_videos.items():
             full_path, video_tensor = _get_video_tensor(VIDEO_DIR, test_video)
@@ -1237,11 +1227,11 @@ class TestVideoReader(unittest.TestCase):
 
     def test_invalid_file(self):
         set_video_backend('video_reader')
-        with self.assertRaises(RuntimeError):
+        with pytest.raises(RuntimeError):
             io.read_video('foo.mp4')
 
         set_video_backend('pyav')
-        with self.assertRaises(RuntimeError):
+        with pytest.raises(RuntimeError):
             io.read_video('foo.mp4')
 
     def test_audio_present_pts(self):
@@ -1258,8 +1248,7 @@ class TestVideoReader(unittest.TestCase):
                     set_video_backend(backend)
                     _, audio, _ = io.read_video(
                         full_path, start_offset, end_offset, pts_unit='pts')
-                    self.assertGreaterEqual(audio.shape[0], 1)
-                    self.assertGreaterEqual(audio.shape[1], 1)
+                    assert all([dimension > 0 for dimension in audio.shape[:2]])
 
     def test_audio_present_sec(self):
         """Test if audio frames are returned with sec unit."""
@@ -1275,9 +1264,8 @@ class TestVideoReader(unittest.TestCase):
                     set_video_backend(backend)
                     _, audio, _ = io.read_video(
                         full_path, start_offset, end_offset, pts_unit='sec')
-                    self.assertGreaterEqual(audio.shape[0], 1)
-                    self.assertGreaterEqual(audio.shape[1], 1)
+                    assert all([dimension > 0 for dimension in audio.shape[:2]])
 
 
-if __name__ == "__main__":
-    unittest.main()
+if __name__ == '__main__':
+    pytest.main([__file__])

test/test_videoapi.py

 import collections
 import os
-import unittest
+import pytest
+from pytest import approx
 
 import torch
 import torchvision
@@ -62,10 +63,10 @@ test_videos = {
 }
 
 
-@unittest.skipIf(_HAS_VIDEO_OPT is False, "Didn't compile with ffmpeg")
+@pytest.mark.skipif(_HAS_VIDEO_OPT is False, reason="Didn't compile with ffmpeg")
 @PY39_SKIP
-class TestVideoApi(unittest.TestCase):
-    @unittest.skipIf(av is None, "PyAV unavailable")
+class TestVideoApi:
+    @pytest.mark.skipif(av is None, reason="PyAV unavailable")
     def test_frame_reading(self):
         for test_video, config in test_videos.items():
             full_path = os.path.join(VIDEO_DIR, test_video)
@@ -77,11 +78,7 @@ class TestVideoApi(unittest.TestCase):
                 for av_frame in av_reader.decode(av_reader.streams.video[0]):
                     vr_frame = next(video_reader)
 
-                    self.assertAlmostEqual(
-                        float(av_frame.pts * av_frame.time_base),
-                        vr_frame["pts"],
-                        delta=0.1,
-                    )
+                    assert float(av_frame.pts * av_frame.time_base) == approx(vr_frame["pts"], abs=0.1)
 
                     av_array = torch.tensor(av_frame.to_rgb().to_ndarray()).permute(
                         2, 0, 1
@@ -94,18 +91,14 @@ class TestVideoApi(unittest.TestCase):
                     # by decoding (around 1%)
                     # TODO: asses empirically how to set this? atm it's 1%
                     # averaged over all frames
-                    self.assertTrue(mean_delta.item() < 2.5)
+                    assert mean_delta.item() < 2.5
 
             av_reader = av.open(full_path)
             if av_reader.streams.audio:
                 video_reader = VideoReader(full_path, "audio")
                 for av_frame in av_reader.decode(av_reader.streams.audio[0]):
                     vr_frame = next(video_reader)
-                    self.assertAlmostEqual(
-                        float(av_frame.pts * av_frame.time_base),
-                        vr_frame["pts"],
-                        delta=0.1,
-                    )
+                    assert float(av_frame.pts * av_frame.time_base) == approx(vr_frame["pts"], abs=0.1)
 
                     av_array = torch.tensor(av_frame.to_ndarray()).permute(1, 0)
                     vr_array = vr_frame["data"]
@@ -114,7 +107,7 @@ class TestVideoApi(unittest.TestCase):
                         torch.abs(av_array.float() - vr_array.float())
                     )
                     # we assure that there is never more than 1% difference in signal
-                    self.assertTrue(max_delta.item() < 0.001)
+                    assert max_delta.item() < 0.001
 
     def test_metadata(self):
         """
@@ -125,12 +118,8 @@ class TestVideoApi(unittest.TestCase):
             full_path = os.path.join(VIDEO_DIR, test_video)
             reader = VideoReader(full_path, "video")
             reader_md = reader.get_metadata()
-            self.assertAlmostEqual(
-                config.video_fps, reader_md["video"]["fps"][0], delta=0.0001
-            )
-            self.assertAlmostEqual(
-                config.duration, reader_md["video"]["duration"][0], delta=0.5
-            )
+            assert config.video_fps == approx(reader_md["video"]["fps"][0], abs=0.0001)
+            assert config.duration == approx(reader_md["video"]["duration"][0], abs=0.5)
 
     def test_seek_start(self):
         for test_video, config in test_videos.items():
@@ -149,7 +138,7 @@ class TestVideoApi(unittest.TestCase):
             for frame in video_reader:
                 start_num_frames += 1
 
-            self.assertEqual(start_num_frames, num_frames)
+            assert start_num_frames == num_frames
 
             # now seek the container to < 0 to check for unexpected behaviour
             video_reader.seek(-1)
@@ -157,7 +146,7 @@ class TestVideoApi(unittest.TestCase):
             for frame in video_reader:
                 start_num_frames += 1
 
-            self.assertEqual(start_num_frames, num_frames)
+            assert start_num_frames == num_frames
 
     def test_accurateseek_middle(self):
         for test_video, config in test_videos.items():
@@ -178,23 +167,23 @@ class TestVideoApi(unittest.TestCase):
                 for frame in video_reader:
                     middle_num_frames += 1
 
-                self.assertTrue(middle_num_frames < num_frames)
-                self.assertAlmostEqual(middle_num_frames, num_frames // 2, delta=1)
+                assert middle_num_frames < num_frames
+                assert middle_num_frames == approx(num_frames // 2, abs=1)
 
                 video_reader.seek(duration / 2)
                 frame = next(video_reader)
                 lb = duration / 2 - 1 / md[stream]["fps"][0]
                 ub = duration / 2 + 1 / md[stream]["fps"][0]
-                self.assertTrue((lb <= frame["pts"]) & (ub >= frame["pts"]))
+                assert (lb <= frame["pts"]) and (ub >= frame["pts"])
 
     def test_fate_suite(self):
         video_path = fate("sub/MovText_capability_tester.mp4", VIDEO_DIR)
         vr = VideoReader(video_path)
         metadata = vr.get_metadata()
 
-        self.assertTrue(metadata["subtitles"]["duration"] is not None)
+        assert metadata["subtitles"]["duration"] is not None
         os.remove(video_path)
 
 
-if __name__ == "__main__":
-    unittest.main()
+if __name__ == '__main__':
+    pytest.main([__file__])