remove torch as install requirement (#14)

* remove torch as install requirement

* make the warning more concise

pyproject.toml

@@ -28,7 +28,7 @@ order_by_type = true
 combine_star = true
 filter_files = true
 
-known_third_party = ["pytest"]
+known_third_party = ["pytest", "_pytest"]
 known_first_party = ["torch", "pytest_pytorch"]
 known_local_folder = ["tests"]
 

pytest_pytorch/plugin.py

@@ -1,11 +1,27 @@
 import re
 import unittest.mock
+import warnings
 from typing import Pattern
 
 from _pytest.unittest import TestCaseFunction, UnitTestCase
 
-from torch.testing._internal.common_device_type import get_device_type_test_bases
-from torch.testing._internal.common_utils import TestCase as PyTorchTestCaseTemplate
+try:
+    from torch.testing._internal.common_device_type import get_device_type_test_bases
+    from torch.testing._internal.common_utils import TestCase as PyTorchTestCaseTemplate
+
+    TORCH_AVAILABLE = True
+except ImportError:
+    TORCH_AVAILABLE = False
+
+    warnings.warn(
+        "Disabling the plugin 'pytest-pytorch', because 'torch' could not be imported."
+    )
+
+    def get_device_type_test_bases():
+        return []
+
+    class PyTorchTestCaseTemplate:
+        pass
 
 
 class PytestPyTorchInternalError(Exception):
@@ -93,6 +109,9 @@ def collect(self):
 
 
 def pytest_pycollect_makeitem(collector, name, obj):
+    if not TORCH_AVAILABLE:
+        return None
+
     try:
         if (
             not issubclass(obj, PyTorchTestCaseTemplate)

setup.cfg

@@ -31,7 +31,6 @@ include_package_data = True
 python_requires = >=3.6
 install_requires =
     pytest
-    torch
 
 [options.packages.find]
 exclude =

tox.ini

@@ -28,6 +28,7 @@ pytorch_channel = nightly
 deps =
   pytest >= 6
   pytest-mock >= 3.1
+  torch
   # The nightlies do not specify numpy as requirement
   numpy
 commands =