Jonathan Lebrun Jonathan Lebrun - 1 year ago 101
Java Question

The Junit message (expected was ...) is not displayed in the console with logback

I use Logback with SLF4J (migrate from log4j) and when I run a junit test that fails, the reason why the test fails is not displayed (AssertionFailedError : expected is <> but was <>)

All other logs are running.

My logback configuration :


<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<pattern>%d{yyyy-MM-dd HH:mm:ss} [%thread] %-5level %msg%n</pattern>
<filter class="com.jle.athleges.logback.TrashFilter">

<appender name="TRASH_FILE_APPENDER"

<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
<!-- daily rollover -->
<pattern>%relative [%thread] %-5level %logger{35} - %msg%n</pattern>

<logger name="org.springframework">
<appender-ref ref="TRASH_FILE_APPENDER" />

<root level="debug">
<appender-ref ref="STDOUT" />
<appender-ref ref="TRASH_FILE_APPENDER" />

My Unit Test :

public void getAllMembers() {
log.debug("Start getAllMember");

long sizeBefore = repository.count();
Member a = new Member();

Member b = new Member();

Assert.assertTrue(memberService.getAll().size() == 0);
log.debug("End getAllMember");

As you see my service return more than 0 elements and my test fails. So, I receive this message :

at org.junit.Assert.assertTrue(
at org.junit.Assert.assertTrue(
at com.jle.athleges.test.integration.MemberServiceImpTest.getAllMembers(
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at ...

With Log4J the statement was java.lang.AssertionError Expected <0> was <2>

Even if I use DEBUG instead of ERROR, the result is the same.

I don't understand why the part Expected <0> was <2> is not displayed


Answer Source

You are asserting a boolean:

Assert.assertTrue(memberService.getAll().size() == 0);

The framework just knows you want to see a true value, but not what the source of the value is. By the time the assertion is called, memberService.getAll().size() == 0 has already been evaluated. Usually it's a better idea to use more specific assertions.

You could start with

assertEquals(0, memberService.getAll().size())

That would give you the Expected <0> was <2> output.

But I personally prefer the Hamcrest style of assertions:

assertThat(memberService.getAll(), is(empty()))

where both is and empty are static imports:

import static;
import static org.hamcrest.collection.IsEmptyCollection.empty;

This makes sure both the test code and its output are most readable.

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