test: detect broken podman (#2483)

Improved podman detection so we fail fast if current installation does
not pass `podman info` minimal test. This should save time running
tests on systems what are not properly configured.

Skips will happen only on platforms that are known not to support
podman, but on those supporting it, tests will fail.

Enables lru_cache on podman/docker checks in order to improve
testing runtime performance.

molecule/test/functional/conftest.py

@@ -84,7 +84,7 @@ def skip_test(request, driver_name):
     msg_tmpl = "Skipped '{}' not supported"
     support_checks_map = {
         'docker': supports_docker,
-        'podman': lambda: min_ansible("2.8.6") and platform.system() != 'Darwin',
+        'podman': supports_podman,
         'delegated': lambda: True,
     }
     try:
@@ -253,11 +253,16 @@ def get_docker_executable():
     return distutils.spawn.find_executable('docker')
 
 
+def get_podman_executable():
+    return distutils.spawn.find_executable('podman')
+
+
 def get_virtualbox_executable():
     return distutils.spawn.find_executable('VBoxManage')
 
 
 @pytest.helpers.register
+@util.lru_cache()
 def supports_docker():
     docker = get_docker_executable()
     if docker:
@@ -277,6 +282,29 @@ def supports_docker():
     return True
 
 
+@pytest.helpers.register
+@util.lru_cache()
+def supports_podman():
+    # Returns true if podman is supported and working
+    # Returns false if podman in not supported
+    # Calls pytest.fail if podman appears to be broken
+    podman = get_podman_executable()
+    if not min_ansible("2.8.6") or platform.system() == 'Darwin' or not podman:
+        return False
+
+    result = util.run([podman, "info"], stdout=PIPE, universal_newlines=True)
+    if result.returncode != 0:
+        LOG.error(
+            "Error %s returned from `podman info`: %s",
+            result.returncode,
+            result.stdout,
+        )
+        pytest.fail("Cannot run podman tests with a broken podman installation.")
+        return False
+
+    return True
+
+
 def min_ansible(version):
     """Ensure current Ansible is newer than a given a minimal one."""
     try: