Improved error messages for toHaveAttr, will address issue # 184

[jesperronn]

...use of failure.

Different error messages if

• element not found
• attribute not found
• incorrect attribute value

See issue #184

[jesperronn]

Please let me know if this is the way we want to present error messages, and I can modify some more matchers.

In my opinion, it makes it much easier -- and faster -- to find errors.

One caveat: I don't know how I can actually write tests that verify text displayed when failures. Can somebody help out?

(I added tests in the bottom in and xdescribe() block so that the build wouldn't fail

[jesperronn]

@RLovelett, I think your suggestion is great :) +1

[travisjeffery]

this looks fine to me, but i think all the relevant matchers should be consistent. do you mind updating them all to be the same? also i wouldn't worry about testing what message is shown since it won't really help much imo.

[jesperronn]

@travisjeffery Totally agree that mactchers should behave consistently, and therefore all matchers should be fixed. Also, I may want more eyes on the nature of my suggested fix in this pull-request. For my taste, it's a lot of code and if statements.

Perhaps somebody has suggestions to make it leaner and prettier?