fix(ngMockE2E): allow $httpBackend.passThrough() to work when ngMock is loaded

[schmod]

Allow $httpBackend.passThrough() to work normally when ngMock is loaded concurrently with ngMockE2E. This also allows one to use angular.mock.module() to write tests that depend on ngMockE2E, as module() always adds a dependency on ngMock.

Fixes #1434

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[schmod]

@googlebot I signed it!

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CLAs look good, thanks!

[schmod]

What does one need to do to get a PR merged around here?

[Narretz]

Hi @schmod I see that this PR is a response to #1434

Can you give me a quick scenario where you need both ngMock and ngMockE2E in the same app?

[schmod]

Hi @Narretz,

For me, the passthrough is useful when I have a test fixture that cannot be easily inlined into JavaScript (such as an image).

I have an Angular directive and service that convert (user-provided) images into clickable thumbnails when they exceed a certain size.

The most straightforward (and realistic) way to test this functionality is to provide a real image as my test fixture, and actually let the browser make a real HTTP request to grab the image.

I suspect that there are also many other integration testing scenarios that could benefit from the semantics of a unit test, with occasional "real" HTTP requests thrown in. This workflow is difficult to achieve in practice, because the window.inject() function provided by angular-mocks loads ngMock, regardless of whether I ask for it (which seriously hampers the usefulness of using ngMockE2E for anything other than a strict End-To-End test).

Hope this helps! I realize that my proposed solution isn't the most ideal, but it doesn't seem like it would make things worse for anybody.

[petebacondarwin]

LGTM - merging

[mike-bresnahan]

This change had a bad side effect on protractor. Protractor no longer waits for pass through requests.

angular/protractor#3948

[mike-bresnahan]

I'm not an expert on Angular internals, but this change smells bad because it causes 2 instances of $httpBackend and dependent services (e.g. $browser) to exist and that violates the implied "all services are singletons" policy of Angular. This is bound to cause people issues (e.g. protractor).

[petebacondarwin]

@mike-bresnahan - can you create a new issue for this. I see that the problem is that calling angular.injector(...) creates a completely new injector and that not only creates a new backend but also an inaccessible copy of the $browser service.

[mike-bresnahan]

Petebacondarwin, yes that is my understanding of the root cause as well and I have created a new issue for it.

#15593