Jest unit tests

[tobika]

Hello,
first this PR is not necessarily there to be merged (certainly not in the master branch). It is there to try out if it is possible to use jest as a testrunner for unit tests in ionic.

I started integration unit tests with karma and jasmine which is already a great improvement if we want to test our applications. After having seen the usage of jest in a workshop it seems that there are some really great features that could make testing ionic/angular even more pleasant.

• Only run tests on modified files
• Only run tests for modified files since last commit

It would be great to have some feedback from the ionic team about the usage of jest. Feel free to try out the modifications in this PR and give feedback. I am just beginning with unit tests and don't understand much yet but hope ionic becomes a pleasant environment for testing :)

There is one error with jest that I couldn't resolve yet, as soon as we add the NavController to page 1 jest shows this error:
No provider for NavController! at Error (native)

@danielsogl this might interest you aswell

[imrvshah]

@tobika

It is a very nice compile example. I tried with the same link using Jest-angular-present. I was facing the problem about ionic storage and lodash.js library. I was getting
Same error If I use lodash.js.

I know that we can fix this with ignoring ng_modules like

But unfortunately, it didn't work for me.

[datencia]

Hi all, I've got a little repo with an example of testing Ionic2 with Jest. I hope you find it useful.