Best way to unit test I18nContext as Cannot read properties of undefined (reading 'lang')

[BenSegniBA]

A quick question, as I've looked about the web and haven't found anything so far.

I have a message service which makes use of the I18nService as a dependency and also I18nContext.current().lang in order to set the desired language.

Inside my message service I have created a simple message method that returns a translated string based on status code:

const currentLanguage = I18nContext.current().lang; <-- issue is here

switch (statusCode) {
	case HttpStatus.AMBIGUOUS:
		return this._i18n.translate('exceptions.AMBIGUOUS', {
			lang: currentLanguage,
		});

This all works fine and translations return when I manually test the currentLanguage constant.

The issue I have is unit testing the service.

I have created a basic mocki18nservice, but when the method is triggered in the test, I consistently get:

TypeError: Cannot read properties of undefined (reading 'lang')

Has anyone found a way of mocking this yet? I have looked over multiple projects using the package, but there isn't any test files on show to see how this has been done in the past.