There is the Recaptcha library

https://github.com/samueljseay/recaptcha

which helps me in verifying recaptcha responses. All nice. Time for testing (yeah, after getting code to work somehow – apologies to all TDD fans). Obviously I don’t want to hit uncle google with my tests, so:

Mox.defmock(MyApplication.Accounts.MockRecaptcha, for: MyApplication.Accounts.RecaptchaBehaviour)

inside test_helper.ex. Needed to define that behaviour separately:

defmodule MyApplication.Accounts.RecaptchaBehaviour do
	@callback verify(String.t(), Keyword.t()) :: {:ok, Response.t()} | {:error, [atom]}
	@callback verify(String.t()) :: {:ok, Response.t()} | {:error, [atom]}
end

do some tests using:

MyApplication.Accounts.MockRecaptcha
|> expect(:verify, fn _response -> {:ok, _response} end)

So far so good, except… all other tests are now failing with:

** (Mox.UnexpectedCallError) no expectation defined for MyApplication.Accounts.MockRecaptcha.verify/1 in process #PID<0.854.0> with args [nil]

Reading the fine docs I find: “[…] you might want the implementation to fall back to a stub (or actual) implementation when no expectations are defined. stub_with/2 is just what you need!”

So another line in test_helper.ex:

Mox.stub_with(MyApplication.Accounts.MockRecaptcha, Recaptcha)

That doesn’t work because ** (ArgumentError) Recaptcha does not implement any behaviour, Well.. let’s add my own “proxy” then, which does:

defmodule MyApplication.Accounts.Recaptcha do
	@behaviour MyApplication.Accounts.RecaptchaBehaviour

	def verify(response, options \\ []) do
		Recaptcha.verify(response, options)
	end
end

And change the test_helper.ex line to

Mox.stub_with(MyApplication.Accounts.MockRecaptcha, MyApplication.Accounts.Recaptcha)

Now the ArgumentError is gone but all tests with no Mox expectations fail the same as before. No change with and without the stub_with/2.

And I feel like I spent already far too much time with it… Any help to put me on track?