/*
 * Copyright (C) 2022 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

@file:OptIn(ExperimentalCoroutinesApi::class)

package com.android.wallpaper.testing

import kotlin.coroutines.CoroutineContext
import kotlin.coroutines.EmptyCoroutineContext
import kotlinx.coroutines.CoroutineStart
import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.Job
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.launch
import kotlinx.coroutines.test.TestScope
import kotlinx.coroutines.test.runCurrent

/** Collect [flow] in a new [Job] and return a getter for the last collected value. */
fun <T> TestScope.collectLastValue(
    flow: Flow<T>,
    context: CoroutineContext = EmptyCoroutineContext,
    start: CoroutineStart = CoroutineStart.DEFAULT,
): () -> T? {
    var lastValue: T? = null
    backgroundScope.launch(context, start) { flow.collect { lastValue = it } }
    return {
        runCurrent()
        lastValue
    }
}