rds_instance_info/tests: add unit-tests

Extend the unit-test coverage of the `rds_instance_info` module.

- break up `instance_info()`
- use exception to handle the API failures

plugins/modules/rds_instance_info.py

@@ -377,11 +377,24 @@ def _describe_db_instances(conn, **params):
     return results
 
 
-def instance_info(module, conn):
-    instance_name = module.params.get('db_instance_identifier')
-    filters = module.params.get('filters')
+class RdsInstanceInfoFailure(Exception):
+    def __init__(self, original_e, user_message):
+        self.original_e = original_e
+        self.user_message = user_message
+        super().__init__(self)
+
+
+def get_instance_tags(conn, arn):
+    try:
+        return boto3_tag_list_to_ansible_dict(
+            conn.list_tags_for_resource(ResourceName=arn,
+                                        aws_retry=True)['TagList'])
+    except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
+        raise RdsInstanceInfoFailure(e, "Couldn't get tags for instance %s" % arn)
 
-    params = dict()
+
+def instance_info(conn, instance_name, filters):
+    params = {}
     if instance_name:
         params['DBInstanceIdentifier'] = instance_name
     if filters:
@@ -390,16 +403,15 @@ def instance_info(module, conn):
     try:
         results = _describe_db_instances(conn, **params)
     except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
-        module.fail_json_aws(e, "Couldn't get instance information")
+        raise RdsInstanceInfoFailure(e, "Couldn't get instance information")
 
     for instance in results:
-        try:
-            instance['Tags'] = boto3_tag_list_to_ansible_dict(conn.list_tags_for_resource(ResourceName=instance['DBInstanceArn'],
-                                                                                          aws_retry=True)['TagList'])
-        except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
-            module.fail_json_aws(e, "Couldn't get tags for instance %s" % instance['DBInstanceIdentifier'])
+        instance['Tags'] = get_instance_tags(conn, arn=instance['DBInstanceArn'])
 
-    return dict(changed=False, instances=[camel_dict_to_snake_dict(instance, ignore_list=['Tags']) for instance in results])
+    return {
+        "changed": False,
+        "instances": [camel_dict_to_snake_dict(instance, ignore_list=['Tags']) for instance in results]
+    }
 
 
 def main():
@@ -415,7 +427,13 @@ def main():
 
     conn = module.client('rds', retry_decorator=AWSRetry.jittered_backoff(retries=10))
 
-    module.exit_json(**instance_info(module, conn))
+    instance_name = module.params.get('db_instance_identifier')
+    filters = module.params.get('filters')
+
+    try:
+        module.exit_json(**instance_info(conn, instance_name, filters))
+    except RdsInstanceInfoFailure as e:
+        module.fail_json_aws(e.original_e, e.user_message)
 
 
 if __name__ == '__main__':

tests/unit/plugins/modules/test_rds_instance_info.py

@@ -0,0 +1,121 @@
+# (c) 2022 Red Hat Inc.
+#
+# This file is part of Ansible
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+from ansible_collections.amazon.aws.plugins.modules import rds_instance_info
+from unittest.mock import MagicMock, Mock, patch, ANY
+import ansible.module_utils.basic
+import botocore.exceptions
+import pytest
+
+
+mod_name = "ansible_collections.amazon.aws.plugins.modules.rds_instance_info"
+
+
+def a_boto_exception():
+    return botocore.exceptions.UnknownServiceError(
+        service_name="Whoops", known_service_names="Oula"
+    )
+
+
+@patch(mod_name + "._describe_db_instances")
+@patch(mod_name + ".get_instance_tags")
+def test_instance_info_one_instance(m_get_instance_tags, m_describe_db_instances):
+    conn = MagicMock()
+    instance_name = "my-instance"
+    m_get_instance_tags.return_value = []
+    m_describe_db_instances.return_value = [
+        {
+            "DBInstanceIdentifier": instance_name,
+            "DBInstanceArn": "arn:aws:rds:us-east-2:123456789012:og:" + instance_name,
+        }
+    ]
+    rds_instance_info.instance_info(conn, instance_name, filters={})
+
+    m_describe_db_instances.assert_called_with(conn, DBInstanceIdentifier=instance_name)
+    m_get_instance_tags.assert_called_with(
+        conn, arn="arn:aws:rds:us-east-2:123456789012:og:" + instance_name
+    )
+
+
+@patch(mod_name + "._describe_db_instances")
+@patch(mod_name + ".get_instance_tags")
+def test_instance_info_all_instances(m_get_instance_tags, m_describe_db_instances):
+    conn = MagicMock()
+    m_get_instance_tags.return_value = []
+    m_describe_db_instances.return_value = [
+        {
+            "DBInstanceIdentifier": "first-instance",
+            "DBInstanceArn": "arn:aws:rds:us-east-2:123456789012:og:first-instance",
+        },
+        {
+            "DBInstanceIdentifier": "second-instance",
+            "DBInstanceArn": "arn:aws:rds:us-east-2:123456789012:og:second-instance",
+        },
+    ]
+    rds_instance_info.instance_info(conn, instance_name=None, filters={"engine": "postgres"})
+
+    m_describe_db_instances.assert_called_with(conn, Filters=[{'Name': 'engine', 'Values': ['postgres']}])
+    assert m_get_instance_tags.call_count == 2
+    m_get_instance_tags.assert_called_with(
+        conn, arn="arn:aws:rds:us-east-2:123456789012:og:second-instance"
+    )
+
+
+def test_get_instance_tags():
+    conn = MagicMock()
+    conn.list_tags_for_resource.return_value = {
+        "TagList": [
+            {"Key": "My-tag", "Value": "the-value$"},
+        ],
+        "NextToken": "some-token",
+    }
+
+    tags = rds_instance_info.get_instance_tags(
+        conn, "arn:aws:rds:us-east-2:123456789012:og:second-instance"
+    )
+    conn.list_tags_for_resource.assert_called_with(
+        ResourceName="arn:aws:rds:us-east-2:123456789012:og:second-instance",
+        aws_retry=True,
+    )
+    assert tags == {"My-tag": "the-value$"}
+
+
+def test_api_failure_get_tag():
+    conn = MagicMock()
+    conn.list_tags_for_resource.side_effect = a_boto_exception()
+
+    with pytest.raises(rds_instance_info.RdsInstanceInfoFailure):
+        rds_instance_info.get_instance_tags(conn, "arn:blabla")
+
+
+def test_api_failure_describe():
+    conn = MagicMock()
+    conn.get_paginator.side_effect = a_boto_exception()
+
+    with pytest.raises(rds_instance_info.RdsInstanceInfoFailure):
+        rds_instance_info.instance_info(conn, None, {})
+
+
+@patch(mod_name + ".AnsibleAWSModule")
+def test_main_success(m_AnsibleAWSModule):
+    m_module = MagicMock()
+    m_AnsibleAWSModule.return_value = m_module
+
+    rds_instance_info.main()
+
+    m_module.client.assert_called_with("rds", retry_decorator=ANY)
+    m_module.exit_json.assert_called_with(changed=False, instances=[])
+
+
+@patch(mod_name + "._describe_db_instances")
+@patch(mod_name + ".AnsibleAWSModule")
+def test_main_failure(m_AnsibleAWSModule, m_describe_db_instances):
+    m_module = MagicMock()
+    m_AnsibleAWSModule.return_value = m_module
+    m_describe_db_instances.side_effect = a_boto_exception()
+
+    rds_instance_info.main()
+
+    m_module.client.assert_called_with("rds", retry_decorator=ANY)
+    m_module.fail_json_aws.assert_called_with(ANY, "Couldn't get instance information")