Add tox configuration to ease Python 3 port.

.gitignore

@@ -8,6 +8,7 @@
 .installed.cfg
 .mr.developer.cfg
 .pytest_cache/
+.tox/
 bin/
 cache/*.py
 develop-eggs/

src/icemac/__init__.py

@@ -1 +1 @@
-__import__('pkg_resources').declare_namespace(__name__)
+__import__('pkg_resources').declare_namespace(__name__)  # pragma: no cover

src/icemac/ab/__init__.py

@@ -1 +1 @@
-__import__('pkg_resources').declare_namespace(__name__)
+__import__('pkg_resources').declare_namespace(__name__)  # pragma: no cover

tox.ini

@@ -0,0 +1,31 @@
+[tox]
+envlist =
+    py27
+    py38
+
+# Caution: This is no replacement for running the tests using bin/py.test
+#          as it does _not_ run the jshint tests!
+[testenv]
+usedevelop = true
+install_command = pip install --pre --upgrade {opts} {packages}
+# extras = test  # ignores -cconstraints.txt :´(
+deps =
+    -chttps://raw.githubusercontent.com/icemac/icemac.addressbook/master/constraints.txt
+    .[test]
+    git+https://github.com/icemac/icemac.addressbook.git#egg=icemac.addressbook[test]
+    pudb
+    pytest
+    pytest-cov
+    pytest-flake8
+    pytest-instafail
+    pytest-pudb
+    pytest-remove-stale-bytecode
+setenv =
+    zope_i18n_compile_mo_files = True
+    zope_i18n_allowed_languages = de,en
+    CHAMELEON_CACHE = {envtmpdir}
+passenv =
+    HOME
+    PYTHONBREAKPOINT
+commands =
+    pytest []