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Kotlin-Multiplatform state management library

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/*
 * Copyright (C) 2021 Abhi Muktheeswarar
 *
 * 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.
 */

package com.msabhi.flywheel

import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.ExecutorCoroutineDispatcher
import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.asCoroutineDispatcher
import kotlinx.coroutines.test.resetMain
import kotlinx.coroutines.test.setMain
import org.junit.rules.TestWatcher
import org.junit.runner.Description
import java.util.concurrent.Executors

/**
 * Use this rule to update the Main dispatcher ahead of tests. By delegating the main dispatcher to a new thread.
 * we can block the current thread and still dispatch main coroutines
 */

@OptIn(ExperimentalCoroutinesApi::class)
class CoroutineTestRule(
    private val testDispatcher: ExecutorCoroutineDispatcher = Executors.newSingleThreadExecutor()
        .asCoroutineDispatcher(),
) : TestWatcher() {
    override fun starting(description: Description) {
        super.starting(description)
        Dispatchers.setMain(testDispatcher)
    }

    override fun finished(description: Description) {
        super.finished(description)
        Dispatchers.resetMain()
    }
}