Test undo/redo behaviour of text input widgets on macOS.

[bruno-rino]

Widgets tested are:

• TextInput
• MultilineTextInput
• PasswordInput
• NumberInput

The cocoa MultilineTextInput widget has been updated to enable undo.

Replaces PR #2037

PR Checklist:

• All new features have been tested
• All new features have been documented
• I have read the CONTRIBUTING.md file
• I will abide by the code of conduct

[bruno-rino]

This second try was easier. Previously, the NSEvent.keyEventWithType function was ignoring modifierFlags if the characters parameter was a single character... My solution was to set that parameter to None. You seem to have found a better solution.

[freakboy3742]

This looks really good. I've dropped a couple of minor comments inline; once those are cleaned up, this should be good to land! Thanks!

[bruno-rino]

A question of style: I am adding skip to another method that needs it. Do you prefer the call to be pytest.skip() or just skip()? I can see mostly pytest.skip() in the source, but xfail() is always not namespaced.

[freakboy3742]

A question of style: I am adding skip to another method that needs it. Do you prefer the call to be pytest.skip() or just skip()? I can see mostly pytest.skip() in the source, but xfail() is always not namespaced.

My personal preference is pytest.skip(); but that's in the category of "strong opinion, weakly held". It has essentially come down to who is writing a module as to which form is used. If there's an existing usage in the file, stick to that form; if there's not, it's dealer's choice :-)

[freakboy3742]

Awesome - thanks!