main.com.squareup.workflow1.testing.RenderIdempotencyChecker.kt Maven / Gradle / Ivy
package com.squareup.workflow1.testing
import com.squareup.workflow1.BaseRenderContext
import com.squareup.workflow1.Workflow
import com.squareup.workflow1.WorkflowAction
import com.squareup.workflow1.WorkflowInterceptor
import com.squareup.workflow1.WorkflowInterceptor.RenderContextInterceptor
import com.squareup.workflow1.WorkflowInterceptor.WorkflowSession
import java.util.LinkedList
/**
* Intercepts the render pass of the root workflow and runs it twice to ensure that well-written
* unit tests catch side effects being incorrectly performed directly in the render method.
*
* The first render pass is the real one, the second one is a no-op and child workflow renderings
* will be played back, in order, to their renderChild calls.
*/
public object RenderIdempotencyChecker : WorkflowInterceptor {
override fun onRender(
renderProps: P,
renderState: S,
context: BaseRenderContext,
proceed: (P, S, RenderContextInterceptor?) -> R,
session: WorkflowSession
): R {
val recordingContext = RecordingContextInterceptor()
proceed(renderProps, renderState, recordingContext)
// The second render pass should not actually invoke any real behavior.
recordingContext.startReplaying()
return proceed(renderProps, renderState, recordingContext)
.also {
// After the verification render pass, any calls to the context _should_ be passed
// through, to allow the real context to run its usual post-render behavior.
recordingContext.stopReplaying()
}
}
}
/**
* A [RenderContextInterceptor] that can record the result of rendering children over a render pass,
* and then play them back over a second render pass that doesn't actually perform any actions.
*/
private class RecordingContextInterceptor :
RenderContextInterceptor {
private var replaying = false
fun startReplaying() {
check(!replaying) { "Expected not to be replaying." }
replaying = true
}
fun stopReplaying() {
check(replaying) { "Expected to be replaying." }
replaying = false
}
override fun onActionSent(
action: WorkflowAction,
proceed: (WorkflowAction) -> Unit
) {
if (!replaying) {
proceed(action)
} // Else noop
}
private val childRenderings = LinkedList()
override fun onRenderChild(
child: Workflow,
childProps: CP,
key: String,
handler: (CO) -> WorkflowAction,
proceed: (
child: Workflow,
props: CP,
key: String,
handler: (CO) -> WorkflowAction
) -> CR
): CR = if (!replaying) {
proceed(child, childProps, key, handler)
.also { childRenderings.addFirst(it) }
} else {
@Suppress("UNCHECKED_CAST")
childRenderings.removeLast() as CR
}
override fun onRunningSideEffect(
key: String,
sideEffect: suspend () -> Unit,
proceed: (key: String, sideEffect: suspend () -> Unit) -> Unit
) {
if (!replaying) {
proceed(key, sideEffect)
}
// Else noop.
}
}