[ResourceGroupsTaggingAPI] Fix incorrect ARNs for EC2 (getmoto#9491)

Author: gaganpreet

moto/resourcegroupstaggingapi/models.py

@@ -684,8 +684,10 @@ def format_tag_keys(
                     tags = format_tags(self.ec2_backend.tags.get(resource.id, {}))
                     if not tags or not tag_filter(tags):
                         continue
+                    resource_type_part = resource_type.split(":", 1)[1]
+                    resource_arn = f"arn:{self.partition}:ec2:{self.region_name}:{self.account_id}:{resource_type_part}/{resource.id}"
                     yield {
-                        "ResourceARN": f"arn:{self.partition}:ec2:{self.region_name}:{self.account_id}:{resource_type}/{resource.id}",
+                        "ResourceARN": resource_arn,
                         "Tags": tags,
                     }
 

tests/test_resourcegroupstaggingapi/test_resourcegroupstaggingapi.py

@@ -379,19 +379,22 @@ def test_get_resources_ec2():
     # 1 Entry for AMI
     resp = rtapi.get_resources(ResourceTypeFilters=["ec2:image"])
     assert len(resp["ResourceTagMappingList"]) == 1
-    assert "image/" in resp["ResourceTagMappingList"][0]["ResourceARN"]
+    expected_arn = f"arn:aws:ec2:eu-central-1:{ACCOUNT_ID}:image/{image_id}"
+    assert resp["ResourceTagMappingList"][0]["ResourceARN"] == expected_arn
 
     # As were iterating the same data, this rules out that the test above was a fluke
     resp = rtapi.get_resources(ResourceTypeFilters=["ec2:instance"])
     assert len(resp["ResourceTagMappingList"]) == 1
-    assert "instance/" in resp["ResourceTagMappingList"][0]["ResourceARN"]
+    expected_arn = f"arn:aws:ec2:eu-central-1:{ACCOUNT_ID}:instance/{instance_id}"
+    assert resp["ResourceTagMappingList"][0]["ResourceARN"] == expected_arn
 
     # Basic test of tag filters
     resp = rtapi.get_resources(
         TagFilters=[{"Key": "MY_TAG1", "Values": ["MY_VALUE1", "some_other_value"]}]
     )
     assert len(resp["ResourceTagMappingList"]) == 1
-    assert "instance/" in resp["ResourceTagMappingList"][0]["ResourceARN"]
+    expected_arn = f"arn:aws:ec2:eu-central-1:{ACCOUNT_ID}:instance/{instance_id}"
+    assert resp["ResourceTagMappingList"][0]["ResourceARN"] == expected_arn
 
 
 @mock_aws