Move test dependencies to package metadata.

setup.cfg

@@ -57,3 +57,16 @@ ssl =
     wincertstore==0.2; sys_platform=='win32'
 certs =
     certifi==2016.9.26
+tests =
+    mock
+    pytest-flake8
+    flake8-2020; python_version>="3.6"
+    virtualenv>=13.0.0
+    pytest-virtualenv>=1.2.7
+    pytest>=3.7
+    wheel
+    coverage>=4.5.1
+    pytest-cov>=2.5.1
+    paver; python_version>="3.6"
+    futures; python_version=="2.7"
+    pip>=19.1 # For proper file:// URLs support.

tests/requirements.txt

-mock
-pytest-flake8
-flake8-2020; python_version>="3.6"
-virtualenv>=13.0.0
-pytest-virtualenv>=1.2.7
-pytest>=3.7
-wheel
-coverage>=4.5.1
-pytest-cov>=2.5.1
-paver; python_version>="3.6"
-futures; python_version=="2.7"
-pip>=19.1 # For proper file:// URLs support.

tools/tox_pip.py

 import os
 import subprocess
 import sys
+import re
 
 
 def remove_setuptools():
@@ -20,12 +21,29 @@ def bootstrap():
     subprocess.check_call(cmd)
 
 
+def is_install_self(args):
+    """
+    Do the args represent an install of .?
+    """
+    def strip_extras(arg):
+        match = re.match(r'(.*)?\[.*\]$', arg)
+        return match.group(1) if match else arg
+
+    return (
+        'install' in args
+        and any(
+            arg in ['.', os.getcwd()]
+            for arg in map(strip_extras, args)
+        )
+    )
+
+
 def pip(args):
     # Honor requires-python when installing test suite dependencies
     if any('-r' in arg for arg in args):
         os.environ['PIP_IGNORE_REQUIRES_PYTHON'] = '0'
 
-    if '.' in args:
+    if is_install_self(args):
         remove_setuptools()
         bootstrap()
 

tox.ini

@@ -13,7 +13,6 @@ requires =
 pip = python {toxinidir}/tools/tox_pip.py
 
 [testenv]
-deps=-r{toxinidir}/tests/requirements.txt
 pip_version = pip
 install_command = {[helpers]pip} install {opts} {packages}
 list_dependencies_command = {[helpers]pip} freeze --all
@@ -25,6 +24,8 @@ setenv =
 passenv=APPDATA HOMEDRIVE HOMEPATH windir APPVEYOR APPVEYOR_* CI CODECOV_* TRAVIS TRAVIS_* NETWORK_REQUIRED
 commands=pytest --cov-config={toxinidir}/tox.ini --cov-report= {posargs}
 usedevelop=True
+extras =
+	tests
 
 
 [testenv:coverage]