Snackbar

Why do we need a custom component for snackbar testing?

We can't predict when snackbar will appear or disappear because we have no API to watch that behaviour.
So it's hard to realize our test failed because: there are no snackbars, snackbar has already disappeared or it hasn't appeared yet.

How our library works?

We keep all Snackbar showings intentions through the test and give you the ability to check that snackbar showing history.

All snackbar assertions only checks an intention to show a snackbar, e.g. a function call, not a real view render.
Keep that in mind, because snackbar could be broken on layout phase even if test is green.

We use this approach in Avito, because value test stability over assertions depth, and couldn't achieve stable tests with real snackbar layout checks.

How to test snackbars with our library?

1. Add dependencies to Gradle

Kotlin

Add to your build.gradle.kts

dependencies {
    implementation("com.avito.android:snackbar-proxy:$version")
    implementation("com.google.android.material:material:$androidXVersion")
    androidTestImplementation("com.avito.android:snackbar-rule:$version")  
}

Groovy

Add to your build.gradle

dependencies {
    implementation("com.avito.android:snackbar-proxy:$version")
    implementation("com.google.android.material:material:$androidXVersion")
    androidTestImplementation("com.avito.android:snackbar-rule:$version")  
}

1. Replace com.google.android.material.snackbar.Snackbar.show() by our wrapper function

import com.avito.android.snackbar.proxy.showSnackbar
import com.google.android.material.snackbar.Snackbar

val snackbar: Snackbar = TODO("Make a snackbar")
snackbar.showSnackbar()

1. Use our com.avito.android.test.app.second.SnackbarRule in tests

import com.avito.android.test.app.second.SnackbarRule
import org.junit.Test
import org.junit.Rule

class SomeTest {
    
    @get:Rule
    private val rule = SnackbarRule() 

    @Test  
    fun test() {
        // test logic
  
        rule.assertIsShownWith("text")
        rule.assertIsShownWith(Matchers.Is("text"))
        rule.assertIsShownLastWith("text")
        rule.assertIsShownLastWith(Matchers.Is("text"))
    } 
}