Support for pressing Delete key on Android

[michaelgmcd]

Unlike iOS, there doesn't appear a way to press the "Delete" key on Android. For iOS, I'm am able to use the typeText method and the "\b" string. From what I can tell through looking at the code is that either the UIDevice's pressDelete method or the Android Espresso pressKey method are the ways to solve this, however neither of these seem to be exposed to the JavaScript API.

[michaelgmcd]

@LeoNatan, I can probably take care of the PR for this, we'll just need some discussion on the implementation. The way I see it, we can either:

• Manually handle the \b key in the typeText element method on Android:

element.typeText('aa\bcc')
// on Android becomes 
element.typeText('aa')
element._pressKey(67) // internal
element.typeText('cc')

• Expose the pressKey command on Android
  • It doesn't seem like EarlGrey has a pressKey command, so this would be Android only
  • Issue with this is that users will have to manually implement what's in the first option for a cross-platform test
• Expose the pressDelete command on Android
  • Will also require users to manually implement the first option for cross-platform support
  • Doesn't support keys other than Delete

[LeoNatan]

Sadly, \n and \b are not obvious at all on iOS. I think it's probably a good idea to have functions such as pressReturnKey() and pressBackspaceKey() on element (next to typeText), and then inside split the impl to typing \n on iOS and doing the necessary key press for Android. What do you think?

[LeoNatan]

The pressKey() should remain internal, I think.

[LeoNatan]

If you could submit a PR, that would be lovely. Thank you!

[michaelgmcd]

I think the abstraction sounds nice. I'll take another look at this tonight. Should be able to open a PR.