CalculatorScreenTestV2.kt

    @Test
    fun shouldCalculateExpressionsCorrectly() {
        // arrange
        enterFormula("((515 + 87 x 311) - 302) ÷ 27")
        
        // act
        performCalculation()
        
        // assert
        assertResultIs("1010.0")
    }

    private fun enterFormula(formula: String) {
        formula.forEach { character ->
            if (!character.isWhitespace()) {
                val buttonLabel = when (character) {
                    '(', ')' -> "()"
                    else -> character.toString()
                }
                composeRule
                    .onNodeWithText(buttonLabel)
                    .performClick()
            }
        }
    }

    private fun performCalculation() {
        composeRule
            .onNodeWithText("=")
            .performClick()
    }

    private fun assertResultIs(result: String) {
        composeRule
            .onNodeWithText(result)
            .assertIsDisplayed()
    }