Getting Started

1. Add dependency

// app/build.gradle.kts
dependencies {
    androidTestImplementation("me.mmckenna.dejavu:dejavu:0.1.1")
}

2. Enable in your Application

class MyApp : Application() {
    override fun onCreate() {
        super.onCreate()
        Dejavu.enable(app = this)
    }
}

3. Write a test

@get:Rule
val composeTestRule = createRecompositionTrackingRule<MainActivity>()

@Test
fun incrementCounter_onlyValueRecomposes() {
    composeTestRule.onNodeWithTag("inc_button").performClick()
    composeTestRule.onNodeWithTag("counter_value").assertRecompositions(exactly = 1)
    composeTestRule.onNodeWithTag("counter_title").assertStable()
}

createRecompositionTrackingRule wraps createAndroidComposeRule and resets counts before each test. For createComposeRule() or other rule types, see Examples.

What a Failure Looks Like

dejavu.UnexpectedRecompositionsError: Recomposition assertion failed for testTag='product_header'
  Composable: demo.app.ui.ProductHeader (ProductList.kt:29)
  Expected: exactly 0 recomposition(s)
  Actual: 1 recomposition(s)

  All tracked composables:
    ProductListScreen = 1
    ProductHeader    = 1  <-- FAILED
    ProductItem      = 1

  Recomposition timeline:
    #1 at +0ms — param slots changed: [1] | parent: ProductListScreen

  Possible cause:
    1 state change(s) of type Int
    Parameter/parent change detected (dirty bits set)

See the Error Messages Guide for how to read and act on each section.