ensure images are build prior to running tests

Signed-off-by: bcambl <blayne@blaynecampbell.com>

.travis.yml

@@ -7,4 +7,8 @@ python:
 install:
   - pip install -r requirements.txt
 
-script: py.test -vv -n auto
+script:
+  # run tasks marked as 'build_stage' first (ensure docker images are built)
+  - py.test -vv -n auto -m "build_stage"
+  # run the remaining tasks in the test suite
+  - py.test -vv -n auto -m "not build_stage"

test/test_000_build_containers.py

@@ -12,6 +12,9 @@ run_local = testinfra.get_backend(
     ('test/centos.Dockerfile', 'pytest_pihole:centos'),
     ('test/fedora.Dockerfile', 'pytest_pihole:fedora'),
 ])
+# mark as 'build_stage' so we can ensure images are build first when tests
+# are executed in parallel. (not required when tests are executed serially)
+@pytest.mark.build_stage
 def test_build_pihole_image(image, tag):
     build_cmd = run_local('docker build -f {} -t {} .'.format(image, tag))
     if build_cmd.rc != 0: