Add an example/tutorial of using unit tests

[igordmn]

Also we need to add uiTestJUnit4 to gradle plugin:

    object Dependencies {
        val desktop = DesktopDependencies
        val animation get() = composeDependency("org.jetbrains.compose.animation:animation")
        val foundation get() = composeDependency("org.jetbrains.compose.foundation:foundation")
        val material get() = composeDependency("org.jetbrains.compose.material:material")
        val runtime get() = composeDependency("org.jetbrains.compose.runtime:runtime")
        val ui get() = composeDependency("org.jetbrains.compose.ui:ui")
        val materialIconsExtended get() = composeDependency("org.jetbrains.compose.material:material-icons-extended")
        val uiTestJUnit4 get() = composeDependency("org.jetbrains.compose.ui:ui-test-junit4")
    }

[igordmn]

For now we can use this in build.gradle.kts:

dependencies {
    testImplementation(compose("org.jetbrains.compose.ui:ui-test-junit4"))
}

Example of unit test

[igordmn]

Also we need to add docs how to do screenshot-based testing:

val window = TestComposeWindow(width = 1024, height = 768)
window.setContent {

}
File(path).writeBytes(window.surface.makeImageSnapshot().encodeToData()!!.bytes)

[igordmn]

We should also add an important note about JUnit version: createComposeRule only works with JUnit 4.

[tylergannon]

Hi all! Would appreciate any notes at all, on how to get started setting up multiplatform tests using the above mentioned library.

[m-sasha]

Added an example to both the compose multiplatform desktop template, and the imageviewer example project. Do we need anything else here, @igordmn?

[igordmn]

Added an example to both the compose multiplatform desktop template, and the imageviewer example project. Do we need anything else here, @igordmn?

We can close the issue after we add a doc and merge everything to master.

[okushnikov]

Please check the following ticket on YouTrack for follow-ups to this issue. GitHub issues will be closed in the coming weeks.