Fix issue of getByDisplayValue not checking TextInputs defaultValue

[MattAgn]

Summary

This PR aims to solve this issue. Basically the issue to fix is that the byDisplayValue helpers don't check the defaultValue prop of TextInputs.

Requirements

• If a TextInput only has a defaultValue and no value, getByDisplayValue should find it
• If a TextInput has a defaultValue AND a value, getByDisplayValue should only find it by its value and not its defaultValue (since if a value is provided, the default value won't be displayed)

Test plan

• Check that getByDisplayValue and queryByDisplayValue get the TextInput by defaultValue if no value is provided
• Check that getByDisplayValue and queryByDisplayValue don't get the TextInput by defaultValue if a value is provided

[thymikee]

I think we want to be explicit here and check if node.props.value === undefined. Would be great to also have a test for value being 0 and empty string to test that

[MattAgn]

indeed that would be better! which value do we use if value is empty string?
for 0, is is possible that it is the number 0 in an input field ? or will it be "0" ?

[thymikee]

I think it's always gonna be a string for Text, but the only way to be sure would be to test it. I recall numbers also work here, so the Text component may perform some implicit conversion to string.

Nevertheless, if the value is "" the defaultValue is no longer used as the value is set to not-undefined

[MattAgn]

Oh alright I did not know that, I'll make the changes

[MattAgn]

Flow does not let me put 0 in the value prop of the TextInput, it wants a string. Should I ignore it or do we consider it's fine? (especially since we'll now be checking for undefined and not false values)

[thymikee]

No need to test the number then :)

[thymikee]

Thank you!