TestNG: assertNull: Assert null value

‘asserNull’ is used to check whether given object is null or not.

'assertNull' is available in below overloaded forms.

public static void assertNull(Object object)

public static void assertNull(Object object, String message)

AssertNullTest.java

package com.sample.app.assertions;

import static org.testng.Assert.assertNull;

import org.testng.annotations.Test;

public class AssertNullTest {

 @Test
 public void test1() {
  Object obj = null;
  assertNull(obj);
 }

 @Test
 public void test2() {
  Object obj = new Object();
  assertNull(obj, "obj is not null");
 }
}

Run AssertNullTest.java, you will see below messages in console.

[RemoteTestNG] detected TestNG version 7.0.0
PASSED: test1
FAILED: test2
java.lang.AssertionError: obj is not null expected [null] but found [java.lang.Object@371a67ec]
 at org.testng.Assert.fail(Assert.java:97)
 at org.testng.Assert.failNotSame(Assert.java:965)
 at org.testng.Assert.assertNull(Assert.java:898)
 at com.sample.app.assertions.AssertNullTest.test2(AssertNullTest.java:18)
 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.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:133)
 at org.testng.internal.TestInvoker.invokeMethod(TestInvoker.java:584)
 at org.testng.internal.TestInvoker.invokeTestMethod(TestInvoker.java:172)
 at org.testng.internal.MethodRunner.runInSequence(MethodRunner.java:46)
 at org.testng.internal.TestInvoker$MethodInvocationAgent.invoke(TestInvoker.java:804)
 at org.testng.internal.TestInvoker.invokeTestMethods(TestInvoker.java:145)
 at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:146)
 at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:128)
 at java.util.ArrayList.forEach(ArrayList.java:1257)
 at org.testng.TestRunner.privateRun(TestRunner.java:770)
 at org.testng.TestRunner.run(TestRunner.java:591)
 at org.testng.SuiteRunner.runTest(SuiteRunner.java:402)
 at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:396)
 at org.testng.SuiteRunner.privateRun(SuiteRunner.java:355)
 at org.testng.SuiteRunner.run(SuiteRunner.java:304)
 at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:53)
 at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:96)
 at org.testng.TestNG.runSuitesSequentially(TestNG.java:1180)
 at org.testng.TestNG.runSuitesLocally(TestNG.java:1102)
 at org.testng.TestNG.runSuites(TestNG.java:1032)
 at org.testng.TestNG.run(TestNG.java:1000)
 at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:115)
 at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:251)
 at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:77)


===============================================
    Default test
    Tests run: 2, Failures: 1, Skips: 0
===============================================


===============================================
Default suite
Total tests run: 2, Passes: 1, Failures: 1, Skips: 0
===============================================

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