Support test setups that use base config file (#88)

* Refactor option addition

This is a preparatory commit that will make adding future command-line
switches a bit easier.

* Add base config option

Up until now, it was fairly inconvenient to run molecule test suites
that used based configuration file to reduce the duplication of
content in the scenario configs.

This commit adds a command line flag and related INI config option
that allows us to pass --base-config flag to molecule when running
tests.

Author: tadeboro

pytest_molecule/__init__.py

@@ -22,26 +22,33 @@
     from _pytest.nodes import Node
 
 
+def _addoption(group, parser, ini_dest, default, help_msg):
+    opt = "--" + ini_dest.replace("_", "-")
+    group.addoption(opt, action="store", dest=ini_dest, default=default, help=help_msg)
+    parser.addini(ini_dest, help_msg, default=default)
+
+
 def pytest_addoption(parser):
     """Inject new command line options to pytest."""
     group = parser.getgroup("molecule")
-    help_msg = (
+
+    _addoption(
+        group,
+        parser,
+        "molecule_unavailable_driver",
+        None,
         "What marker to add to molecule scenarios when driver is "
-        "unavailable. (ex: skip, xfail). Default: None"
+        "unavailable. (ex: skip, xfail). Default: None",
     )
-    default = None
-    dest = "molecule_unavailable_driver"
-
-    group.addoption(
-        "--molecule-unavailable-driver",
-        action="store",
-        dest=dest,
-        default=default,
-        help=help_msg,
+    _addoption(
+        group,
+        parser,
+        "molecule_base_config",
+        None,
+        "Path to the molecule base config file. The value of this option is "
+        "passed to molecule via the --base-config flag. Default: None",
     )
 
-    parser.addini(dest, help_msg, default=default)
-
 
 def pytest_configure(config):
     """Pytest hook for loading our specific configuration."""
@@ -169,8 +176,11 @@ def runtest(self):
         cwd = os.path.abspath(os.path.join(self.fspath.dirname, "../.."))
         scenario = folders[-1]
         # role = folders[-3]  # noqa
-        cmd = [sys.executable, "-m", "molecule", self.name, "-s", scenario]
 
+        cmd = [sys.executable, "-m", "molecule"]
+        if self.config.option.molecule_base_config:
+            cmd.extend(("--base-config", self.config.option.molecule_base_config))
+        cmd.extend((self.name, "-s", scenario))
         # We append the additional options to molecule call, allowing user to
         # control how molecule is called by pytest-molecule
         opts = os.environ.get("MOLECULE_OPTS")

tests/roles/base_config/base.yml

@@ -0,0 +1,4 @@
+---
+scenario:
+  test_sequence:
+    - converge

tests/roles/base_config/molecule/s1/converge.yml

@@ -0,0 +1,7 @@
+- name: Converge
+  hosts: all
+  gather_facts: false
+  tasks:
+    - name: Converge on s1
+      debug:
+        msg: Scenario 1

tests/roles/base_config/molecule/s1/molecule.yml

@@ -0,0 +1,6 @@
+---
+driver:
+  name: delegated
+
+platforms:
+  - name: localhost

tests/roles/base_config/molecule/s1/prepare.yml

@@ -0,0 +1,8 @@
+---
+- name: Prepare
+  hosts: all
+  gather_facts: false
+  tasks:
+    - name: This should not be executed if base config file is loaded
+      fail:
+        msg: Base config file loading is not working as expected

tox.ini

@@ -20,6 +20,11 @@ commands =
     pytest --collect-only
     # pytest already needs built wheel in dist/
     pytest --color=yes --html={envlogdir}/reports.html --self-contained-html {tty:-s} --molecule-unavailable-driver= -k foo
+    pytest \
+      --molecule-base-config base.yml \
+      --color=yes \
+      {tty:-s} \
+      -k base_config
 # all extras installed in order to detect potential conflicts
 extras =
     ansi