单元测试中的RxJava 2覆盖IO调度程序 [英] RxJava 2 overriding IO scheduler in unit test

问题描述

我正在尝试测试以下RxKotlin/RxJava 2代码:

I'm trying to test the following RxKotlin/RxJava 2 code:

validate(data)
    .subscribeOn(Schedulers.io())
    .observeOn(AndroidSchedulers.mainThread())
    .flatMap { ... }

我试图按如下方式覆盖调度程序:

I'm attempting to override the schedulers as follows:

// Runs before each test suite
RxJavaPlugins.setInitIoSchedulerHandler { Schedulers.trampoline() }
RxAndroidPlugins.setInitMainThreadSchedulerHandler { Schedulers.trampoline() }

但是，运行测试时出现以下错误:

However, I get the following error when running the test:

java.lang.ExceptionInInitializerError
...
Caused by: java.lang.NullPointerException: Scheduler Callable result can't be null
    at io.reactivex.internal.functions.ObjectHelper.requireNonNull(ObjectHelper.java:39)
    at io.reactivex.plugins.RxJavaPlugins.applyRequireNonNull(RxJavaPlugins.java:1317)
    at io.reactivex.plugins.RxJavaPlugins.initIoScheduler(RxJavaPlugins.java:306)
    at io.reactivex.schedulers.Schedulers.<clinit>(Schedulers.java:84)

有人遇到过这个问题吗?

Has anyone experienced this problem?

在使用RxKotlin/RxJava 1并覆盖以下调度程序时，该测试工作正常:

The test worked fine when using RxKotlin/RxJava 1 and the following scheduler overrides:

RxAndroidPlugins.getInstance().registerSchedulersHook(object : RxAndroidSchedulersHook() {
    override fun getMainThreadScheduler() = Schedulers.immediate()
})

RxJavaPlugins.getInstance().registerSchedulersHook(object : RxJavaSchedulersHook() {
    override fun getIOScheduler() = Schedulers.immediate()
})

推荐答案

我建议您采用其他方法，并为调度程序添加抽象层.这个家伙有一个很好的文章关于它.

I suggest you take a different approach and add a layer of abstraction to your schedulers. This guy has a nice article about it.

在Kotlin中看起来像这样

It would look something like this in Kotlin

interface SchedulerProvider {
    fun ui(): Scheduler
    fun computation(): Scheduler
    fun trampoline(): Scheduler
    fun newThread(): Scheduler
    fun io(): Scheduler 
}

然后使用自己的SchedulerProvider实现覆盖它:

And then you override that with your own implementation of SchedulerProvider:

class AppSchedulerProvider : SchedulerProvider {
    override fun ui(): Scheduler {
        return AndroidSchedulers.mainThread()
    }

    override fun computation(): Scheduler {
        return Schedulers.computation()
    }

    override fun trampoline(): Scheduler {
        return Schedulers.trampoline()
    }

    override fun newThread(): Scheduler {
        return Schedulers.newThread()
    }

    override fun io(): Scheduler {
        return Schedulers.io()
    }
}

还有一个用于测试班级的人:

And one for testing classes:

class TestSchedulerProvider : SchedulerProvider {
    override fun ui(): Scheduler {
        return Schedulers.trampoline()
    }

    override fun computation(): Scheduler {
        return Schedulers.trampoline()
    }

    override fun trampoline(): Scheduler {
        return Schedulers.trampoline()
    }

    override fun newThread(): Scheduler {
        return Schedulers.trampoline()
    }

    override fun io(): Scheduler {
        return Schedulers.trampoline()
    }
}

您的代码在调用RxJava时将如下所示:

Your code would look like this where you call RxJava:

mCompositeDisposable.add(mDataManager.getQuote()
        .subscribeOn(mSchedulerProvider.io())
        .observeOn(mSchedulerProvider.ui())
        .subscribe(Consumer<Quote> {
...

您将根据测试位置覆盖SchedulerProvider的实现.这是一个示例项目供参考，我正在链接使用SchedulerProvider的可测试版本的测试文件:

And you'll just override your implementation of SchedulerProvider based on where you test it. Here's a sample project for reference, I am linking the test file that would use the testable-version of SchedulerProvider: https://github.com/Obaied/DingerQuotes/blob/master/app/src/test/java/com/obaied/dingerquotes/QuotePresenterTest.kt#L31

这篇关于单元测试中的RxJava 2覆盖IO调度程序的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！