Junit: @RuleChain: Ordering junit rules

By using RuleChain, we can execute the test rules in specific order.

Example

In the above esample, CustomLogger rule is executed first followed by TestCaseExecutionTimer rule.

Find the below working application.

CustomLogger.java

package com.sample.customrules;

import org.junit.rules.TestRule;
import org.junit.runner.Description;
import org.junit.runners.model.Statement;

public class CustomLogger implements TestRule {

 @Override
 public Statement apply(Statement base, Description description) {
  return new Statement() {
   @Override
   public void evaluate() throws Throwable {
    System.out.println("Executing : " + description.getMethodName());
    base.evaluate();
    System.out.println("Execution done for : " + description.getMethodName());
   }
  };
 }

}

TestCaseExecutionTimer.java

package com.sample.customrules;

import org.junit.rules.TestRule;
import org.junit.runner.Description;
import org.junit.runners.model.Statement;

public class TestCaseExecutionTimer implements TestRule {
 @Override
 public Statement apply(Statement base, Description description) {
  return new Statement() {
   @Override
   public void evaluate() throws Throwable {
    long time1 = System.currentTimeMillis();
    base.evaluate();
    long time2 = System.currentTimeMillis();

    if (description.getMethodName() != null) {
     System.out.println(description.getMethodName() + " takes " + (time2 - time1) + " milliseconds");
    } else {
     System.out.println("Test cases in " + description.getClassName() + " takes " + (time2 - time1)
       + " milliseconds");
    }

   }
  };
 }
}

TestApp.java

package com.sample.test;

import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.RuleChain;

import com.sample.customrules.CustomLogger;
import com.sample.customrules.TestCaseExecutionTimer;

public class TestApp {
 @Rule
 public RuleChain chain = RuleChain.
       outerRule(new CustomLogger()).
       around(new TestCaseExecutionTimer());

 @Test
 public void testCase1() throws InterruptedException {
  Thread.sleep(500);
 }

 @Test
 public void testCase2() throws InterruptedException {
  Thread.sleep(100);
 }

}

Run TestApp.java, you can able to see below messages in console.

Executing : testCase1

testCase1 takes 503 milliseconds

Execution done for : testCase1

Executing : testCase2

testCase2 takes 101 milliseconds

Execution done for : testCase2

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