parameters: handle blank values when argument is a list (#77119)

Fixes: #77108

Signed-off-by: Abhijeet Kasurde <akasurde@redhat.com>

changelogs/fragments/77108_params_blank.yml

@@ -0,0 +1,3 @@
+---
+bugfixes:
+- parameters - handle blank values when argument is a list (https://github.com/ansible/ansible/issues/77108).

lib/ansible/module_utils/common/parameters.py

@@ -651,10 +651,11 @@ def _validate_argument_values(argument_spec, parameters, options_context=None, e
             if param in parameters:
                 # Allow one or more when type='list' param with choices
                 if isinstance(parameters[param], list):
-                    diff_list = ", ".join([item for item in parameters[param] if item not in choices])
+                    diff_list = [item for item in parameters[param] if item not in choices]
                     if diff_list:
                         choices_str = ", ".join([to_native(c) for c in choices])
-                        msg = "value of %s must be one or more of: %s. Got no match for: %s" % (param, choices_str, diff_list)
+                        diff_str = ", ".join(diff_list)
+                        msg = "value of %s must be one or more of: %s. Got no match for: %s" % (param, choices_str, diff_str)
                         if options_context:
                             msg = "{0} found in {1}".format(msg, " -> ".join(options_context))
                         errors.append(ArgumentValueError(msg))

test/units/module_utils/common/arg_spec/test_validate_invalid.py

@@ -100,6 +100,14 @@ INVALID_SPECS = [
         {'req': None},
         set(),
         "missing required arguments: req"
+    ),
+    (
+        'blank_values',
+        {'ch_param': {'elements': 'str', 'type': 'list', 'choices': ['a', 'b']}},
+        {'ch_param': ['']},
+        {'ch_param': ['']},
+        set(),
+        "value of ch_param must be one or more of"
     )
 ]