How can I programmatically click a Button in Jetpack Compose?

In compose you're creating a button with action. You can pass action function and call same function programmatically.

// you need to remember your callback to prevent extra recompositions.
// pass all variables that may change between recompositions
// as keys instead of `Unit`
val onClickAction = remember(Unit) { 
    {
        
        // do some action
    }
}

LaunchedEffect(Unit) {
    // perform action in 1 sec after view appear
    delay(1000)
    onClickAction()
}
Button(
    onClick = onClickAction
) {
    Text(text = "Button")
}

I'd write an instrumentation test with ComposeTestRule for this. performClick() generally works as expected for me on a SemanticNodeInteraction object.

I did run into a problem where it only worked when the element was currently visible though, so I needed to call performScrollTo() first:

composeTestRule.onNode(...).run {
    performScrollTo()
    performClick()
}

Here you go

    Button(
            onClick = {
            // here you can perform you action on button click

            },
            modifier = Modifier
                .fillMaxWidth()
                .height(55.dp)
                .background(
                    color = WoodSmoke,
                    shape = RoundedCornerShape(30)
                ),
            colors = ButtonDefaults.buttonColors(backgroundColor = 
            Color.Transparent),

            ) {
            Text(text = "Sign in", color = Color.White)
        }