Introduction
JUnit is a testing framework for Java. It is primarily aimed for IDEs, but with some perseverance it can be used on the command line.
ConsoleLauncher
You will need ConsoleLauncher, a java executable, to run JUnit from the command line. At time of writing the latest version is junit-platform-console-standalone-1.6.0.jar and can be downloaded from the Maven Repository. Download this file to your working directory.
Create a sample java file
Using your text editor of choice create a file called SampleUnit.java and copy and paste the following code in it:
public class SampleUnit {
public int addInts(int a, int b){
return a + b;
}
public boolean validAboveZero(int a) {
if (a>0) {
return true;
}
return false;
}
}
Create a sample test file
Creating a file called SampleUnitTest.java copy the following:
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.assertEquals;
import org.junit.Test;
public class SampleUnitTest {
@Test
public void testAddInts() {
SampleUnit sampleUnit = new SampleUnit();
int result = sampleUnit.addInts(2, 2);
// The below should fail.
assertEquals("Not adding correctly!", 5, result);
}
@Test
public void testValidAboveZero() {
SampleUnit sampleUnit = new SampleUnit();
boolean result = sampleUnit.validAboveZero(2);
assertTrue(result);
}
@Test
public void testValidFail() {
boolean result = false;
assertFalse(result);
}
}
Compile
Run the following from the command line:
javac SampleUnit.java
javac -cp junit-platform-console-standalone-1.6.0.jar:. SampleUnitTest.java
This assumes the JUnit jar, SampleUnit.java and SampleUnitTest.java are all in the same directory. The compiler will create two new files: SampleUnit.class and SampleUnitTest.class.
Run the tests
Finally at the command line run:
java -jar junit-platform-console-standalone-1.6.0.jar --class-path . -c SampleUnitTest
This should output something like this:
Thanks for using JUnit! Support its development at https://junit.org/sponsoring
╷
├─ JUnit Jupiter ✔
└─ JUnit Vintage ✔
└─ SampleUnitTest ✔
├─ testAddInts ✘ Not adding correctly! expected:<5> but was:<4>
├─ testValidFail ✔
└─ testValidAboveZero ✔
Failures (1):
JUnit Vintage:SampleUnitTest:testAddInts
MethodSource [className = 'SampleUnitTest', methodName = 'testAddInts', methodParameterTypes = '']
=> java.lang.AssertionError: Not adding correctly! expected:<5> but was:<4>
org.junit.Assert.fail(Assert.java:89)
org.junit.Assert.failNotEquals(Assert.java:835)
org.junit.Assert.assertEquals(Assert.java:647)
SampleUnitTest.testAddInts(SampleUnitTest.java:13)
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.base/java.lang.reflect.Method.invoke(Method.java:566)
org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
[...]
Test run finished after 43 ms
[3 containers found]
[0 containers skipped]
[3 containers started]
[0 containers aborted]
[3 containers successful]
[0 containers failed]
[3 tests found]
[0 tests skipped]
[3 tests started]
[0 tests aborted]
[2 tests successful]
[1 tests failed]
ConsoleLauncher Options Frustration
The ConsoleLauncher has an extensive list of command line options for providing arguments. Above I’ve gone for --class-path . -c SampleUnitTest defined respectively as:
-cp, --classpath, --class-path=PATH[;|:PATH...] Provide additional classpath entries -- for example, for adding engines and their dependencies. This option can be repeated.
-c, --select-class=CLASS Select a class for test discovery. This option can be repeated.
Why these two specifically? A simple reason - after a couple of hours reading stack overflow and trying various random combinations, it appears to be the only option I could get to work. This may be due to my incompetence, my setup (openjdk 11.0.6) or a bug.
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