Use pytest and friends in tox

tox.ini

@@ -1,23 +1,45 @@
 [tox]
-envlist = {py36,py37,py38,py39,py310}-{linux,macos,windows}
+minversion = 2.0
+envlist = clean,{py36,py37,py38,py39,py310}-{linux,darwin,windows},report
+skip_missing_interpreters = True
 
 [testenv]
 deps =
+    aiofiles
     bcrypt>=3.1.3
-    coverage
-    linux,macos: gssapi>=1.2.0
+    fido2>=0.9.2
+    gssapi>=1.2.0 ; sys.platform != 'win32'
     libnacl>=1.4.2
     pyOpenSSL>=17.0.0
-    python-pkcs11>=0.7.0
+    pytest
+    pytest-cov
+    pytest-xdist
+    python-pkcs11>=0.7.0 ; sys.platform != 'win32'
+    pywin32>=227 ; sys.platform == 'win32'
     setuptools>=18.5
-    windows: pywin32>=227
-    {py36,py37,py38,py39,py310}-{linux,macos}: uvloop>=0.9.1
+    uvloop>=0.9.1 ; sys.platform != 'win32'
 platform =
     linux: linux
-    macos: darwin
+    darwin: darwin
     windows: win32
-sitepackages = True
-skip_missing_interpreters = True
 usedevelop = True
 commands =
-    {envpython} -m coverage run -p -m unittest
+    {envpython} -m pytest --cov --cov-append -n auto {posargs}
+depends =
+    {py36,py37,py38,py39,py310}-{linux,darwin,windows}: clean
+    report: {py36,py37,py38,py39,py310}-{linux,darwin,windows}
+
+[testenv:clean]
+deps = coverage
+skip_install = true
+commands = coverage erase
+
+[testenv:report]
+deps = coverage
+skip_install = true
+commands =
+    coverage report --show-missing
+    coverage html
+
+[pytest]
+testpaths = tests