Use constrainted environments for testing

In the OpenStack CI, constrainted environment is used for testing
to avoid unexpected gate breakage. This commit introduces it to
networking-nec testing.

Change-Id: If1776088a6e21fc4783a267d60881ec755e3391f

tools/tox_install.sh

@@ -20,6 +20,14 @@ BRANCH_NAME=stable/mitaka
 
 set -e
 
+CONSTRAINTS_FILE=$1
+shift
+
+install_cmd="pip install"
+if [ $CONSTRAINTS_FILE != "unconstrained" ]; then
+    install_cmd="$install_cmd -c$CONSTRAINTS_FILE"
+fi
+
 if [ $neutron_installed -eq 0 ]; then
     echo "ALREADY INSTALLED" > /tmp/tox_install.txt
     echo "Neutron already installed; using existing package"
@@ -33,12 +41,12 @@ elif [ -x "$ZUUL_CLONER" ]; then
        git://git.openstack.org \
        openstack/neutron
    cd openstack/neutron
-   pip install -e .
+   $install_cmd -e .
    cd "$cwd"
 else
     echo "PIP HARDCODE" > /tmp/tox_install.txt
-    pip install -U -egit+https://git.openstack.org/openstack/neutron.git@$BRANCH_NAME#egg=neutron
+    $install_cmd -U -egit+https://git.openstack.org/openstack/neutron.git@$BRANCH_NAME#egg=neutron
 fi
 
-pip install -U $*
+$install_cmd -U $*
 exit $?

tox.ini

@@ -5,11 +5,14 @@ skipsdist = True
 
 [testenv]
 usedevelop = True
-install_command = {toxinidir}/tools/tox_install.sh {opts} {packages}
+install_command =
+  # networking-nec is still targetted to Mitaka development,
+  # so we need to use upper-constraints.txt from stable/mitaka branch.
+  {toxinidir}/tools/tox_install.sh {env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt?h=stable/mitaka} {opts} {packages}
 # Note the hash seed is set to 0 until neutron can be tested with a
 # random hash seed successfully.
 setenv =
-   VIRTUAL_ENV={envdir}
+  VIRTUAL_ENV={envdir}
 deps = -r{toxinidir}/test-requirements.txt
 whitelist_externals = sh
 commands =