如何在 RxJava 2 中使用 TestObserver 对对象列表进行单元测试？

Question

这里有一个 Person class 用来存放人物对象。它具有 Comparable 实现以供比较。

public class Person implements Comparable<Person> {

    private String firstName = "";
    private String lastName = "";

    public Person(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }

    @Override
    public int compareTo(@NonNull Person person) {
        return this.firstName.compareTo(person.getFirstName());
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
}

这是一个 工厂 class，用于创建人员列表和人员列表 Observables。它总是创建相同的一组人。

import java.util.ArrayList;
import io.reactivex.Observable;

public class PeopleFactory {

    public static ArrayList<Person> createPeople() {
        ArrayList<Person> people = new ArrayList<>();

        for (int i=0; i<10; i++) {
            people.add(new Person("Thanks" + i, "Giving" + i));
        }

        return people;
    }

    public static Observable<ArrayList<Person>> createPersonObservable() {
        return Observable.just(createPeople());
    }
}

现在我想使用 RxJava 2 中的 TestObserver 来根据 people Observable.

发出的人员列表来测试人员列表

import org.junit.Test;
import java.util.ArrayList;
import io.reactivex.Observable;
import io.reactivex.observers.TestObserver;


public class PersonTest {
    @Test
    public void testPeople() {
        // Creating a people Observable
        Observable<ArrayList<Person>> peopleObservable = PeopleFactory.createPersonObservable();

        // Creating an test observer and subscribe to the above peopleObservable
        TestObserver<ArrayList<Person>> observer = new TestObserver<>();
        peopleObservable.subscribe(observer);

        // Creating the same people list and assert this people list with the people list from the peopleObservable
        ArrayList<Person> people = PeopleFactory.createPeople();
        observer.assertValue(people);
    }
}

我期待这个测试应该通过，因为 PeopleFactory 正在为普通人员列表和人员列表 Observable 创建同一组人员，并且 Person class 有一个 Comparable，表示对象将是只要 firstName 相等就相等。

但是 测试忽略了这个 Comparable，将它与对象地址进行比较，并给了我以下测试失败消息：

java.lang.AssertionError: Expected: [com.example.myapplication.Person@7006c658, com.example.myapplication.Person@34033bd0, com.example.myapplication.Person@47fd17e3, com.example.myapplication.Person@7cdbc5d3, com.example.myapplication.Person@3aa9e816, com.example.myapplication.Person@17d99928, com.example.myapplication.Person@3834d63f, com.example.myapplication.Person@1ae369b7, com.example.myapplication.Person@6fffcba5, com.example.myapplication.Person@34340fab] (class: ArrayList), Actual: [com.example.myapplication.Person@2aafb23c, com.example.myapplication.Person@2b80d80f, com.example.myapplication.Person@3ab39c39, com.example.myapplication.Person@2eee9593, com.example.myapplication.Person@7907ec20, com.example.myapplication.Person@546a03af, com.example.myapplication.Person@721e0f4f, com.example.myapplication.Person@28864e92, com.example.myapplication.Person@6ea6d14e, com.example.myapplication.Person@6ad5c04e] (class: ArrayList) (latch = 0, values = 1, errors = 0, completions = 1)

    at io.reactivex.observers.BaseTestConsumer.fail(BaseTestConsumer.java:163)
    at io.reactivex.observers.BaseTestConsumer.assertValue(BaseTestConsumer.java:332)
    at com.example.myapplication.PersonTest.testPeople(PersonTest.java:21)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access[=13=]0(ParentRunner.java:58)
    at org.junit.runners.ParentRunner.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:51)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMainV2.main(AppMainV2.java:131)

那么，什么是正确的方法或者我如何在 RxJava 2 中使用 TestObserver 对对象列表进行单元测试？

注：以上所有代码均在AndroidStudio中编写。

Answer 1

来自 Comparable 的 javadoc:

This interface imposes a total ordering on the objects of each class that implements it. ... It is strongly recommended, but not strictly required that (x.compareTo(y)==0) == (x.equals(y)).

Comparable::compareTo方法仅在排序或比较元素顺序时使用。平等是完全独立的，正如您所指出的，正在断言对象身份。

你可以通过查看源码快速确认框架在做什么https://github.com/ReactiveX/RxJava/blob/v2.1.6/src/main/java/io/reactivex/observers/BaseTestConsumer.java#L331

if (!ObjectHelper.equals(value, v)) {
  throw fail("Expected: " + valueAndClass(value) + ", Actual: " + valueAndClass(v));
}

ObjectHelper::equals

public static boolean equals(Object o1, Object o2) { // NOPMD
  return o1 == o2 || (o1 != null && o1.equals(o2));
}

所以它正在调用 Object::equals，您没有为 Person class 超载，所以测试使用对象标识并按预期失败。

Answer 2

感谢@Murka 的回答，在我用 @Override public boolean equals(Object obj)

替换 Comparable 实现后，它按预期工作

public class Person {

    private String firstName = "";
    private String lastName = "";

    public Person(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }


    @Override
    public boolean equals(Object obj) {
        return this.firstName.equalsIgnoreCase(((Person) obj).getFirstName());
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
}

如何在 RxJava 2 中使用 TestObserver 对对象列表进行单元测试？

How to unit test a list of objects using TestObserver in RxJava 2?

java

unit-testing

junit4

observable

rx-java2