Adopts use of module calling method for tools

Avoid annoying warnigns raised by tox about externals when sitepackages
is enabled, mainly because these tools where already found installed
as system packages.

Also simplifies the whitelist_externals usage as there is no real
need to have more than one place to define them.

Signed-off-by: Sorin Sbarnea <ssbarnea@redhat.com>

tox.ini

@@ -46,12 +46,14 @@ extras =
 commands_pre =
     find {toxinidir} -type f -not -path '{toxinidir}/.tox/*' -path '*/__pycache__/*' -name '*.py[c|o]' -delete
 commands =
-    unit: pytest test/unit/ --cov={toxinidir}/molecule/ --no-cov-on-fail {posargs}
-    functional: pytest test/functional/ {posargs}
-    lint: flake8
-    lint: yamllint -s test/ molecule/
+    unit: python -m pytest test/unit/ --cov={toxinidir}/molecule/ --no-cov-on-fail {posargs}
+    functional: python -m pytest test/functional/ {posargs}
+    lint: python -m flake8
+    lint: python -m yamllint -s test/ molecule/
 whitelist_externals =
     find
+    rm
+    sh
 # Enabling sitepackages is needed in order to avoid encountering exceptions
 # caused by missing selinux python bindinds in ansible modules like template.
 # Selinux python bindings are binary and they cannot be installed using pip
@@ -68,15 +70,15 @@ usedevelop = false
 
 [testenv:format]
 commands =
-    yapf -i -r molecule/ test/
+    python -m yapf -i -r molecule/ test/
 deps = yapf>=0.25.0,<0.27
 extras =
 skip_install = true
 usedevelop = false
 
 [testenv:format-check]
 commands =
-    yapf -d -r molecule/ test/
+    python -m yapf -d -r molecule/ test/
 deps = {[testenv:format]deps}
 extras = {[testenv:format]extras}
 skip_install = true
@@ -100,7 +102,7 @@ usedevelop = False
 # Ref: https://twitter.com/di_codes/status/1044358639081975813
 commands =
     python -m setup checkdocs check --metadata --restructuredtext --strict --verbose
-    twine check .tox/dist/*
+    python -m twine check .tox/dist/*
 
 [testenv:build-docker]
 # skip under Windows
@@ -123,9 +125,6 @@ commands =
         --pull --rm \
         {posargs:-t ansible/molecule:$TAG} .\
     '
-whitelist_externals =
-    sh
-
 
 [testenv:build-dists-local]
 description =
@@ -156,6 +155,3 @@ setenv =
 commands =
     rm -rfv {toxinidir}/dist/
     {[testenv:build-dists-local]commands}
-whitelist_externals =
-    rm
-    {[testenv]whitelist_externals}