modify error message when redirected but expecting to render a template

[AEgan]

This change modifies the error message when using expect(response).to have_rendered(:template) when the response is a redirect.

The current error message is

expecting <"template_name"> but rendering with <[]>

This change would modify it to be

expecting <'template_name'> but was a redirect to <(redirect location)>

This will make the problem a bit more clear.

Because the matcher calls assert_template for this, the actual exception is being passed from assert_template to have_rendered, so when the assert_template fails it was just passing the error message along. This change checks to see if the response is a redirect after the assertion fails, and if so replaces the second half of the error message with a message that gives the actual reason for the failure.

[cupakromer]

Thanks for improving this! 💙 This will definitely help debugging controller specs.

Because the matcher calls assert_template for this, the actual exception is being passed from assert_template to have_rendered, so when the assert_template fails it was just passing the error message along.

😲 Yeah, at some point we really should update our matchers to no rely on those assert_xyz methods.

[cupakromer]

This needs a YARD doc comment.

[AEgan]

I added a YARD doc and comments, and changed the param name in the spec. Let me know if you want anything modified or if you want me to squash the commits!

[cupakromer]

Looks good. I think we just need a change log entry. And then merge when this is green.

Also I've opened #1441 so we can make this process easier in the future.

[cupakromer]

Thanks