[Feature] add expect(locator).toContainClass()

Hi there)

I have a strange behavior with toHaveClass assertion.

I have an html

<label class="MuiInputLabel-root MuiInputLabel-formControl MuiInputLabel-animated MuiInputLabel-outlined MuiFormLabel-root MuiFormLabel-colorPrimary Mui-error css-1958la6-MuiFormLabel-root-MuiInputLabel-root" data-shrink="false" for="mui-1" id="mui-1-label"></label>

And I have assertion:

await expect(label).toHaveClass('Mui-error')

which fails, but this one is good:

await expect(label).toHaveClass('MuiInputLabel-root MuiInputLabel-formControl MuiInputLabel-animated MuiInputLabel-outlined MuiFormLabel-root MuiFormLabel-colorPrimary Mui-error css-1958la6-MuiFormLabel-root-MuiInputLabel-root')

Is that intended?

I expected toHaveClass be like: “Hey, label, do you have class Mui-error in your bag?”, but instead I have “Hey, label, do you have exactly one class and is it Mui-error?”.

[bboyle]

noting that .toHaveClass(/(^|\s)active(\s|$)/) is a more reliable workaround, but would really love the simpler API proposed here! Working with an angular app and the material library and elements have a lot of classes, I really only want to test for a specific one (e.g. is the “active” class present or not), preferably without the hard to read regex 😃

[mxschmitt]

@Diokuz we can add toContainClass for that.

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