Managed package callout invoked from managed package extension causing test class failure

Question

We have a managed package that has executes a HTTP callout from a trigger that calls a future method on the insertion of new records on a particular object. We have a managed package extension that inserts records on the managed package object which invokes a callout through the managed package.

The problem is in test classes in the managed package extension. The test classes are failing because it is inserting these records which cause a callout through the managed package. Normally you would just implement Test.setMock(HttpCalloutMock.class,..) inside the Test.startTest() logic however it is not working.

From what I have read you must implement the Test.setMock method from within the managed package that is actually doing the callout. Has anyone dealt with this before?

Is the solution as simple as building in logic in the managed package trigger to recognize that it is being executed from a managed package extension and to then invoke Test.setMock from the trigger prior to the attempted callout?

For example:

Option 1:

1. Managed Package Extension inserts new records
2. Managed Package Extension sets a global variable value inside of the Managed Package
3. Managed Package trigger fires and looks at the global variable and implements Test.setMock since it was invoked from the managed package extension.

Option 2: Add logic in the trigger to always invoke Test.setMock when it is running in a test context (Test.isRunningTest()).

Thoughts?

Answer 1

I have something similar in a package I have built - a series of apex classes that make callouts to a third party web service. The expectation is that a customer will then build their own VF controllers to utilize my classes, and the data they return. To get round the issue you raise, I built a globally available method in a class in my managed package that sets the mock interface. So if a customer writes a test class in their own instance that references my code, so long as they call that method in my package, the mock callout is being invoked from within my package, and the callout uses the mock interface/response. I would think it would work the same with an extension package.