Support more Ansible versions

Support running the molecule tests against more versions of Ansible.
By typing

  LSR_ANSIBLE_DEP=<ansible> LSR_MSCENARIO=<scenario> tox -e molecule

one can run molecule inside tox with <ansible> version installed
under <scenario> scenario. For example

  LSR_ANSIBLE_DEP='ansible==2.7.*' LSR_MSCENARIO=foo tox -e molecule

will run molecule under scenario 'foo' and the recent Ansible 2.7
installed. `tox -e molecule` run molecule under default scenario
with the latest Ansible (from pypi) installed.

Travis runs molecule tests for Ansible 2.6, 2.7, and 2.8 installed
and under default scenario (can be overriden by user in config.sh).

Additional changes: Remove useless comment from custom.sh.

.travis.yml

@@ -2,6 +2,10 @@
 ---
 dist: xenial
 language: python
+env:
+  global:
+    - LSR_ANSIBLES='ansible==2.6.* ansible==2.7.* ansible==2.8.*'
+    - LSR_MSCENARIOS='default'
 matrix:
   include:
     - python: 2.6

.travis/config.sh

@@ -7,6 +7,11 @@
 #
 #       - LSR_EXTRA_PACKAGES
 #
+#   * .travis/runtox:
+#
+#       - LSR_ANSIBLES
+#       - LSR_MSCENARIOS
+#
 # Environment variables that not start with LSR_* but have influence on CI
 # process:
 #

.travis/custom.sh

@@ -13,7 +13,6 @@ ME=$(basename $0)
 SCRIPTDIR=$(readlink -f $(dirname $0))
 TOPDIR=$(readlink -f ${SCRIPTDIR}/..)
 
-# Include library and config:
 . ${SCRIPTDIR}/utils.sh
 . ${SCRIPTDIR}/config.sh
 

.travis/runtox

@@ -1,16 +1,45 @@
 #!/bin/bash
 # SPDX-License-Identifier: MIT
 
-set -ex
+# Run tox. Additionally, if LSR_MSCENARIOS is defined, run `tox -e molecule`
+# for every scenario from LSR_MSCENARIOS and for every Ansible version from
+# LSR_ANSIBLES.
+#
+# LSR_MSCENARIOS is a space separated list of molecule scenarios.
+# LSR_ANSIBLES is a space separated list of Ansible package names with versions
+# in pip format, i.e 'ansible ansible==2.6 ansible==2.7 ansible=2.8'.
+#
+# LSR_MSCENARIOS and LSR_ANSIBLES can be set in .travis/config.sh or as
+# environment variables.
 
-SCRIPTDIR=$(dirname $0)
-CONFIG=${SCRIPTDIR}/config.sh
+ME=$(basename $0)
+SCRIPTDIR=$(readlink -f $(dirname $0))
+BANNERSIZE=90
 
-if [[ -f ${CONFIG} ]]; then
-  . ${CONFIG}
+. ${SCRIPTDIR}/utils.sh
+. ${SCRIPTDIR}/config.sh
+
+lsr_banner "tox" ${BANNERSIZE}
+(set -x; tox); error_code=$?
+
+# Exit prematurely if the environment is not suitable for running
+# Molecule tests.
+if ! lsr_venv_python_matches_system_python; then
+  exit $error_code
 fi
 
-tox "$@"
-for X in ${LSR_MSCENARIOS}; do
-  LSR_MSCENARIO=${X} tox -e molecule
+for ansible_dependency in ${LSR_ANSIBLES}; do
+  for molecule_scenario in ${LSR_MSCENARIOS}; do
+    lsr_banner \
+      "[${ansible_dependency}] tox -e molecule -- -s ${molecule_scenario}" \
+      ${BANNERSIZE}
+    (
+      set -x
+      LSR_ANSIBLE_DEP="${ansible_dependency}" \
+      LSR_MSCENARIO=${molecule_scenario} \
+      tox -e molecule
+    ) || error_code=$?
+  done
 done
+
+exit $error_code

tox.ini

@@ -174,6 +174,7 @@ commands =
 
 [molecule_common]
 deps =
+    {env:LSR_ANSIBLE_DEP:ansible}
     docker
     molecule
     selinux
@@ -263,7 +264,7 @@ max-line-length = 88
 python =
   2.6: py26,custom
   2.7: py27,flake8,pylint,custom
-  3.5: coveralls,molecule,custom
+  3.5: coveralls,custom
   3.6: py36,black,custom
   3.7: py37,custom
   3.8: py38,custom