Check arity of functions being mocked #433 broke Mocking of Amazonica APIs

carnellj commented 5 years ago

Hi @philomates ,

I am seeking some advice. The Amazonica libraries allow you to pass in a map containing the credentials for the call. For example:

(ec2/describe-images {:endpoint properties/ec2-endpoint} :image-ids [ami-id]))

This first parameter on every call is option and they are basically using a macro call and coercion to map everything to the underlying Amazon call. As a result, almost all of the Amazonica APIs have only only 1 parameter and their code coerces the extra leading parameter.

My mocks always include the parameters {:endpoint} map and then extra value. However, with fix #433 you are now forcing the mocked parameters to match the expected parameter list. I am not disagreeing that this is necessarily a bad thing, but I am seeking your thoughts on how I can work through the issue I described above. I am being forced to upgrade for (JDK 11 dependencies) and this is now breaking my builds.

Any help or thoughts you can give would be appreciated.

Thanks,
  John

philomates commented 5 years ago

Hey @carnellj,

I imagine you are referring to the following, using [amazonica "0.3.139"] and [midje "1.9.5"]

(ns reproduce-amazonica-issue
  (:require [midje.sweet :refer :all]
            [amazonica.aws.ec2 :as ec2]))

(defn call-amazonica []
  (ec2/describe-images :owners ["self"] :image-ids ["ami-f00f9699" "ami-e0d30c89"]))

(fact
  (call-amazonica) => irrelevant
  (provided
    (ec2/describe-images :owners ["self"] :image-ids ["ami-f00f9699" "ami-e0d30c89"]) => nil))

which results in

FAIL at (core_test.clj:13)
You faked #'describe-images with an argument count that doesn't match the function's defined arg
uements:
Provided 4 argument(s), where valid options are: 0, 1 arguments

FAIL at (core_test.clj:13)
These calls were not made the right number of times:
    (ec2/describe-images :owners ["self"] :image-ids ["ami-f00f9699" "ami-e0d30c89"]) [expected
at least once, actually never called]

I believe this is due to an issue with how the amazonica library defines the :arglists metadata for its wrapped amazon functions (here). It builds the arglist to match the java api, which doesn't match how the actual clojure wrapper should be called.

For example:

(-> #'ec2/describe-images meta :arglists)
;; => ([] [describe-images-request])

I think this leaves us with 3 options:

ask the amazonica folks to change the arglist metadata to match the actual way that the clojure functions should be called
introduce config parameter to midje that lets you turn off the change made in https://github.com/marick/Midje/pull/433
in your code you can manually remove the :arglists metadata from all amazonica usages. For example, put the following at the top of test namespaces: (alter-meta! #'ec2/describe-images #(dissoc % :arglists))

I think the 1st is the most sensical, but maybe not the easiest, with the last being a last resort hack. I can add the config parameter if you'd like, but I'd prefer to see if amazonica can be adapted first.

cheers!

carnellj commented 5 years ago

Hi Phillip,

Thanks for the quick turnaround on my question. I know appreciate you taking the time. What you have pointed out is exactly the problem. I will reach out to the Amazonica team and see if they are willing or able to address it.

Thanks again for the help.

- John

marick / Midje

Check arity of functions being mocked #433 broke Mocking of Amazonica APIs #452