Add method to tox to use local neutron-lib with unit tests

Change-Id: Ic96bb04cc3f9ed1438596b2150030ab22887b091

TESTING.rst

@@ -509,6 +509,41 @@ To run only the unit tests::
 
     tox -e py27
 
+Many changes span across both the neutron and neutron-lib repos, and tox
+will always build the test environment using the published module versions
+specified in requirements.txt and lower-constraints.txt. To run tox tests
+against a different version of neutron-lib, use the TOX_ENV_SRC_MODULES
+environment variable to point at a local package repo.
+
+For example, to run against the 'master' branch of neutron-lib:
+
+    cd $SRC
+    git clone git://git.openstack.org/openstack/neutron-lib
+    cd $NEUTRON_DIR
+    env TOX_ENV_SRC_MODULES=$SRC/neutron-lib tox -r -e pep8,py27
+
+To run against a change of your own, repeat the same steps, but use the
+directory with your changes, not a fresh clone.
+
+To run against a particular gerrit change of the lib (substituting the
+desired gerrit refs for this example):
+
+    cd $SRC
+    git clone git://git.openstack.org/openstack/neutron-lib
+    cd neutron-lib
+    git fetch git://git.openstack.org/openstack/neutron-lib refs/changes/13/635313/6 && git checkout FETCH_HEAD
+    cd $NEUTRON_DIR
+    env TOX_ENV_SRC_MODULES=$SRC/neutron-lib tox -r -e pep8,py27
+
+Note that the '-r' is needed to re-create the tox virtual envs, and will also
+be needed to restore them to standard when not using this method.
+
+Any pip installable package can be overriden with this environment variable,
+not just neutron-lib. To specify multiple packages to override, specify them
+as a space separated list to TOX_ENV_SRC_MODULES. Example:
+
+    env TOX_ENV_SRC_MODULES="$SRC/neutron-lib $SRC/oslo.db" tox -r -e pep8,py27
+
 Functional Tests
 ~~~~~~~~~~~~~~~~
 

tools/pip_install_src_modules.sh

@@ -0,0 +1,25 @@
+#!/bin/bash
+
+# For neutron unit tests, you can define git repos containing modules
+# that you want to use to override the requirements-based packages.
+#
+# Why, you ask? Because you made changes to neutron-lib, and you want
+# run the unit tests together.  E.g.:
+#
+#   env TOX_ENV_SRC_MODULES="$HOME/src/neutron-lib" tox -e py27
+
+toxinidir="$1"
+
+if [ -z "$TOX_ENV_SRC_MODULES" ]; then
+    exit 0
+fi
+
+for repo in $TOX_ENV_SRC_MODULES; do
+    d="${toxinidir}/${repo}"
+    if [ ! -d "$d" ]; then
+        echo "tox_env_src: error: no directory found at $d"
+        continue
+    fi
+    echo "tox_env_src: pip installing from $d"
+    pip install -e "$d"
+done

tox.ini

@@ -9,7 +9,7 @@ setenv = VIRTUAL_ENV={envdir}
          OS_STDOUT_CAPTURE={env:OS_STDOUT_CAPTURE:true}
          OS_STDERR_CAPTURE={env:OS_STDERR_CAPTURE:true}
          PYTHONWARNINGS=default::DeprecationWarning,ignore::DeprecationWarning:distutils,ignore::DeprecationWarning:site
-passenv = TRACE_FAILONLY GENERATE_HASHES http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
+passenv = TRACE_FAILONLY GENERATE_HASHES http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY TOX_ENV_SRC_MODULES
 usedevelop = True
 install_command =
   pip install {opts} {packages}
@@ -18,7 +18,10 @@ deps =
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/test-requirements.txt
 whitelist_externals = sh
-commands = stestr run {posargs}
+commands =
+  {toxinidir}/tools/pip_install_src_modules.sh "{toxinidir}"
+  stestr run {posargs}
+
 # there is also secret magic in ostestr which lets you run in a fail only
 # mode. To do this define the TRACE_FAILONLY environmental variable.