Add option to select test cases by markers

Change-Id: I773b710eb4f4a8abb1cebc13088d3cc16ff08334

infrared_plugin/plugin.spec

@@ -191,6 +191,12 @@ subparsers:
             type: Value
             help: Extra options to be passed to PyTest
             ansible_variable: pytest_addopts
+          pytest-markers:
+            type: Value
+            help: >
+                only run tests matching given mark expression.
+                For example: --pytest-markers 'mark1 and not mark2'.
+            ansible_variable: pytest_markers
           pytest-maxfail:
             type: Value
             help: Max number of test case failures before aborting

roles/tobiko-tox/defaults/main.yaml

@@ -21,7 +21,7 @@ tox_constraints: ''
 
 tox_constrain_env:
   PYTEST_ADDOPTS: >
-     {% if not test_flaky%}-m 'not flaky'{% endif %}
+     {% if pytest_markers %}-m '{{ pytest_markers }}'{% endif %}
      {% if pytest_maxfail %}--maxfail '{{ pytest_maxfail }}'{% endif %}
      {{ pytest_addopts }}
   TOX_REPORT_DIR: '{{ tox_report_dir }}'
@@ -37,5 +37,6 @@ tox_expected_rcs:
 ignore_test_failures: no
 
 pytest_addopts: ''
+pytest_markers: "{% if not test_flaky%}not flaky{% endif %}"
 pytest_maxfail: ''
 test_flaky: false