[SOLVED] how to assert that text not contains specific characters in android jetpack compose testing?

how to assert that text not contains specific characters in android jetpack compose testing?

I'm trying to write some test cases for my compose functions. I have an outlined Text field with a maximum value of 16 characters. So I want to test this feature. Here is the test:

    @Test
    fun checkMaxTaxCodeLength_16Character() {
        val taxCode = composeRule.onNodeWithTag(testTag = AUTHENTICATION_SCREEN_TAX_CODE_EDIT_TEXT)
        for (i in 'A'..'Z')
            taxCode.performTextInput(i.toString())
        taxCode.assertTextEquals("ABCDEFGHIJKLMNOP")
    }

But although I can see the input is correct, the test fails, and it seems assertTextEquals doesn't work correctly. So:

first of all, what am I doing wrong?
Second, is there any way to, instead of checking the equality, check the text does not contain specific characters?

here is the code of text field:

                OutlinedTextField(
                    value = state.taxCode,
                    maxLines = 1,
                    onValueChange = { string ->
                        viewModel.onEvent(
                            AuthenticationEvent.TaxCodeChanged(string)
                        )
                    },
                    label = {
                        Text(text = stringResource(id = R.string.tax_code))
                    },
                    modifier = Modifier
                        .fillMaxWidth()
                        .testTag(TestingConstant.AUTHENTICATION_SCREEN_TAX_CODE_EDIT_TEXT)
                )

The maximum length is handled in the view model. If the user adds more characters than 16, the view model won't update the state and keep the old value.

Solution

Ok, still, the problem is open, but I achieved what I wanted another way. I used semantic nodes to get what is in edit text and compared it with what it should be:

    @Test
    fun checkMaxTaxCodeLength_16Character() {
        val taxCode = composeRule.onNodeWithTag(testTag = AUTHENTICATION_SCREEN_TAX_CODE_EDIT_TEXT)
        for (i in 'A'..'Z')
            taxCode.performTextInput(i.toString())
        for ((key,value) in taxCode.fetchSemanticsNode().config)
            if (key.name =="EditableText")
                assertEquals("ABCDEFGHIJKLMNOP",value.toString())
    }