CalculatorScreenRobotV2.kt

class CalculatorScreenRobot(
    private val composeRule: AndroidComposeTestRule<ActivityScenarioRule<MainActivity>, MainActivity>
) {

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

    inner class Act {
        fun performCalculation() {
            composeRule
                .onNodeWithText("=")
                .performClick()
        }
    }

    inner class Assert {
        fun assertResultIs(result: String) {
            composeRule
                .onNodeWithText(result)
                .assertIsDisplayed()
        }
    }
}