Add tox plugin to handle --testmon (#107)

- sets TESTMON_DATAFILE to use a data file per tox venv
- installs pytest-testmon into a tox venv when --testmon gets used

setup.py

@@ -14,7 +14,10 @@
  entry_points={
  'pytest11': [
  'testmon = testmon.pytest_testmon',
- ]
+ ],
+ 'tox': [
+ 'testmon = testmon.tox_testmon',
+ ],
  },
  install_requires=['pytest>=2.8.0,<4', 'coverage>=4'],
  classifiers=[

testmon/tox_testmon.py

@@ -0,0 +1,57 @@
+"""
+A tox plugin to automatically install and use pytest-testmon with tox.
+
+It installs pytest-testmon once `--testmon` is used in one of the commands
+(starting with "pytest" or "py.test").
+
+It also sets the TESTMON_DATAFILE environment variable (always) to use a
+datafile in the venv's directory.
+
+It uses the tox_runenvreport hook instead of tox_testenv_install_deps (where
+it could just add the dep unconditionally) to only install pytest-testmon on
+demand. Changing envconfig.deps on demand would re-create the venv.
+"""
+import os
+
+import pluggy
+from tox.config import DepConfig
+
+hookimpl = pluggy.HookimplMarker("tox")
+
+
+def _uses_testmon(envconfig):
+ """Test if an envconfig uses testmon by looking at the command(s).
+
+ The command will include resolved {posargs} already, i.e. arguments passed
+ on the command line.
+ """
+ for command in envconfig.commands:
+ if command[0] == 'pytest' or command[0] == 'py.test':
+ if '--testmon' in command:
+ return True
+ return False
+
+
+def touch_stampfile(venv):
+ open(venv.path.join('.testmon_installed'), 'a').close()
+
+
+def installed_testmon(venv):
+ return os.path.exists(venv.path.join('.testmon_installed'))
+
+
+@hookimpl
+def tox_runenvreport(venv, action):
+ datafile = str(venv.path.join('.testmondata'))
+ action.setactivity('testmon', 'setting TESTMON_DATAFILE=%s' % datafile)
+ venv.envconfig.setenv['TESTMON_DATAFILE'] = datafile
+
+ if (_uses_testmon(venv.envconfig)
+ and 'pytest-testmon' not in (x.name for x in venv.envconfig.deps)):
+ if not installed_testmon(venv):
+ action.setactivity('testmon', 'installing pytest-testmon')
+ # Uses _install for handling configured indexservers.
+ # venv.run_install_command(['pytest-testmon'], action=action)
+ venv._install([DepConfig('pytest-testmon')], action=action)
+
+ touch_stampfile(venv)