feat: add the value expected in getBy error messages

[sregg]

Implements #549

Summary

Add the value that was expected in error message for the following methods:

• getByText('bla') => No instances found with text 'bla'
• getByPlaceholderText('bla') => No instances found with placeholder text 'bla'
• getByDisplayValue('bla') => No instances found with display value 'bla'
• getByA11yLabel('bla') => No instances found with accessibilityLabel 'bla'
• getByA11yHint('bla') => No instances found with accessibilityHint 'bla'
• getByA11yRole('bla') => No instances found with accessibilityRole 'bla'
• getByA11yStates('bla') => No instances found with accessibilityStates 'bla'
• getByA11yState({ disabled: true}) => No instances found with accessibilityState '{"disabled":true}'
• getByA11yValue({ min: 50 }) => No instances found with accessibilityValue '{"min":50}'

Test plan

I updated some tests to expect the new error message

[mdjastrzebski]

Nice work @sregg! 👍

I've added some suggestions for improving code readability.

[mdjastrzebski]

Suggested change

	`${prepareErrorMessage(error)} with text '${
	typeof text === 'string' ? text : text.toString()
	}'`,
	`${prepareErrorMessage(error)} with text '${text}'`,

We should probably be able to the if condition, sa template string should do the checks & toString() call for us.

[sregg]

That was my first idea but I was getting this Flow error:

Cannot coerce `text` to string because  `RegExp` [1] should not be coerced.

[sregg]

${text.toString()}

seems to work

Would you be happy with that @mdjastrzebski?

[thymikee]

@sregg doing text.toString() or String(text) (generally safer) is the way to go here, yea 👍

[thymikee]

Btw, I think that prepareErrorMessage function is a perfect place for handling this extra text. Similar to what you have in a test here: https://github.com/callstack/react-native-testing-library/pull/550/files#diff-4246008ab708750218ff9e41118401a1R14

[mdjastrzebski]

Suggested change

	`${prepareErrorMessage(error)} with placeholder text '${
	typeof placeholder === 'string' ? placeholder : placeholder.toString()
	}'`,
	`${prepareErrorMessage(error)} with placeholder '${placeholder}'`,

We should probably be able to the if condition, sa template string should do the checks & toString() call for us.

[mdjastrzebski]

Suggested change

	`${prepareErrorMessage(error)} with display value '${
	typeof displayValue === 'string'
	? displayValue
	: displayValue.toString()
	}'`,
	`${prepareErrorMessage(error)} with display value '${displayValue}'`,

We should probably be able to the if condition, sa template string should do the checks & toString() call for us.

[mdjastrzebski]

What is the reason for using JSON.stringify instead of toString like in other places?

[sregg]

I'm getting this error if I use toString()

Cannot call `matcher.toString` because property `toString` is missing in  mixed

[thymikee]

we have pretty-format in our deps, so let's use that with {min: true} option set: https://github.com/facebook/jest/tree/master/packages/pretty-format#usage-with-options

[sregg]

@thymikee I addressed your comments in my latest commit

[thymikee]

👍

addressed

[thymikee]

Thank you!