How to compare two lists with JUnit

Question

I am trying to compare two array of strings with Java 8 syntax.

List<String> days= dayPartsList.get(0).getWeekdays()
                .stream()
                .sorted(Comparator.comparing(WeekdayModel::getName))
                .map(x -> x.getName().toUpperCase())
                .collect(Collectors.toList());
List<DayOfWeek> daysofWeeks =Arrays
                .stream(DayOfWeek.values())
                .sorted(Comparator.comparing(x -> x.getDisplayName(TextStyle.FULL, Locale.CANADA)))
                .collect(Collectors.toList());

assertEquals(days,daysofWeeks);

When I run the code, I get the following error in the console.

java.lang.AssertionError: expected: java.util.ArrayList<[FRIDAY, MONDAY, SATURDAY, SUNDAY, THURSDAY, TUESDAY, WEDNESDAY]> but was: java.util.ArrayList<[FRIDAY, MONDAY, SATURDAY, SUNDAY, THURSDAY, TUESDAY, WEDNESDAY]>
Expected :java.util.ArrayList<[FRIDAY, MONDAY, SATURDAY, SUNDAY, THURSDAY, TUESDAY, WEDNESDAY]> 
Actual   :java.util.ArrayList<[FRIDAY, MONDAY, SATURDAY, SUNDAY, THURSDAY, TUESDAY, WEDNESDAY]>
 <Click to see difference>


    at org.junit.Assert.fail(Assert.java:88)
    at org.junit.Assert.failNotEquals(Assert.java:743)
    at org.junit.Assert.assertEquals(Assert.java:118)
    at org.junit.Assert.assertEquals(Assert.java:144)
    at com.monkey.service.intergrationTest.MenuCallTest.readGetDayPartsTest(MenuCallTest.java:93)
    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$1.runReflectiveCall(FrameworkMethod.java:47)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:74)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:83)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:72)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:233)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:87)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:176)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:160)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70

Both the actual and expected results look the same, but the test still does not work. Does anyone know what is going on here? Thanks

Answer 1

Firstly, your problem is really not specific to java 8 Streamas here you want to compare List, compiled by yourself Stream, not Stream.

Both actual and expected results look the same, but the test still fails.

"", , , , String , , a List<String> List<DayOfWeek>.
, , .

Assert.assertEquals(Object, Object) equals() , , :

public class Assert {
    ...    
    private static boolean isEquals(Object expected, Object actual) {
        return expected.equals(actual);
    }
    ...    
}

DayOfWeek toString(), , equals() String, String.

, List , assertEqual() .