Updating @slow marker for pytest.

The old method (using the `pytest.config` global) is deprecated.

For reference:

https://docs.pytest.org/en/latest/example/simple.html#control-skipping-of-tests-according-to-command-line-option
https://docs.pytest.org/en/latest/deprecations.html#pytest-config-global
https://docs.pytest.org/en/latest/mark.html

tests/conftest.py

@@ -22,8 +22,14 @@
 import sys
 import unittest
 
+import pytest
 import six
 
+try:
+    from bezier import _HAS_SPEEDUP as HAS_SPEEDUP
+except ImportError:  # pragma: NO COVER
+    HAS_SPEEDUP = False
+
 if six.PY2:
     import mock  # pylint: disable=import-error
 
@@ -38,3 +44,20 @@ def pytest_addoption(parser):
         action="store_true",
         help="Ignore slow tests.",
     )
+
+
+def pytest_configure(config):
+    config.addinivalue_line("markers", "slow: mark test as slow to run")
+
+
+def pytest_collection_modifyitems(config, items):
+    if not config.getoption("--ignore-slow"):
+        return
+
+    if HAS_SPEEDUP:
+        return
+
+    skip_slow = pytest.mark.skip(reason="--ignore-slow ignores the slow tests")
+    for item in items:
+        if "slow" in item.keywords:
+            item.add_marker(skip_slow)

tests/unit/test__surface_helpers.py

@@ -15,21 +15,11 @@
 import numpy as np
 import pytest
 
-try:
-    from bezier import _HAS_SPEEDUP as HAS_SPEEDUP
-except ImportError:  # pragma: NO COVER
-    HAS_SPEEDUP = False
 from tests.unit import utils
 
 UNIT_TRIANGLE = np.asfortranarray([[0.0, 1.0, 0.0], [0.0, 0.0, 1.0]])
 FLOAT64 = np.float64  # pylint: disable=no-member
 SPACING = np.spacing  # pylint: disable=no-member
-# pylint: disable=invalid-name,no-member
-slow = pytest.mark.skipif(
-    pytest.config.getoption("--ignore-slow") and not HAS_SPEEDUP,
-    reason="--ignore-slow ignores the slow tests",
-)
-# pylint: enable=invalid-name,no-member
 
 
 class Test_polynomial_sign(unittest.TestCase):
@@ -503,7 +493,7 @@ def test_linear(self):
             UNIT_TRIANGLE, 1, expected_a, expected_b, expected_c, expected_d
         )
 
-    @slow
+    @pytest.mark.slow
     def test_line_check_evaluate(self):
         # Use a fixed seed so the test is deterministic and round
         # the nodes to 8 bits of precision to avoid round-off.
@@ -540,7 +530,7 @@ def test_quadratic(self):
         )
         self._helper(nodes, 2, expected_a, expected_b, expected_c, expected_d)
 
-    @slow
+    @pytest.mark.slow
     def test_quadratic_check_evaluate(self):
         # Use a fixed seed so the test is deterministic and round
         # the nodes to 8 bits of precision to avoid round-off.
@@ -668,21 +658,21 @@ def test_cubic(self):
         )
         self._helper(nodes, 3, expected_a, expected_b, expected_c, expected_d)
 
-    @slow
+    @pytest.mark.slow
     def test_cubic_check_evaluate(self):
         # Use a fixed seed so the test is deterministic and round
         # the nodes to 8 bits of precision to avoid round-off.
         nodes = utils.get_random_nodes(shape=(2, 10), seed=346323, num_bits=8)
         self._points_check(nodes, 3)
 
-    @slow
+    @pytest.mark.slow
     def test_quartic_check_evaluate(self):
         # Use a fixed seed so the test is deterministic and round
         # the nodes to 8 bits of precision to avoid round-off.
         nodes = utils.get_random_nodes(shape=(2, 15), seed=741002, num_bits=8)
         self._points_check(nodes, 4)
 
-    @slow
+    @pytest.mark.slow
     def test_on_the_fly(self):
         # Test for a degree where the subdivision is done on the fly
         # rather than via a stored matrix.