Use pytest and friends in tox

.coveragerc

@@ -9,5 +9,6 @@ exclude_lines =
 partial_branches =
     pragma: no branch
     for .*
-omit =
-    .tox/*
+include =
+    asyncssh/*
+    tests/*

tox.ini

@@ -1,23 +1,48 @@
 [tox]
-envlist = {py36,py37,py38,py39,py310}-{linux,macos,windows}
+minversion = 3.7
+envlist = clean,{py36,py37,py38,py39,py310}-{linux,darwin,windows},report
+skip_missing_interpreters = True
 
 [testenv]
 deps =
+    aiofiles>=0.6.0
     bcrypt>=3.1.3
-    coverage
-    linux,macos: gssapi>=1.2.0
+    fido2>=0.9.2
     libnacl>=1.4.2
     pyOpenSSL>=17.0.0
-    python-pkcs11>=0.7.0
+    pytest>=7.0.1
+    pytest-cov>=3.0.0
     setuptools>=18.5
+    linux,darwin: gssapi>=1.2.0
+    linux,darwin: python-pkcs11>=0.7.0
+    linux,darwin: uvloop>=0.9.1
     windows: pywin32>=227
-    {py36,py37,py38,py39,py310}-{linux,macos}: uvloop>=0.9.1
 platform =
     linux: linux
-    macos: darwin
+    darwin: darwin
     windows: win32
-sitepackages = True
-skip_missing_interpreters = True
 usedevelop = True
+setenv =
+    {py36,py37,py38,py39,py310}-{linux,darwin,windows}: COVERAGE_FILE = .coverage.{envname}
+commands =
+    {envpython} -m pytest --cov --cov-report=term-missing:skip-covered {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
+parallel_show_output = true
 commands =
-    {envpython} -m coverage run -p -m unittest
+    coverage combine
+    coverage report --show-missing
+    coverage html
+
+[pytest]
+testpaths = tests