Assertion
All the assertions are in the Assert class.
public class Assert extends java.lang.Object
This class provides a set of assertion methods, useful for writing tests. Only failed assertions are recorded. Some of the important methods of Assert class are as follows −
Sr.No. Methods & Description
1 void assertEquals(boolean expected, boolean actual)
Checks that two primitives/objects are equal.
2 void assertTrue(boolean condition)
Checks that a condition is true.
3 void assertFalse(boolean condition)
Checks that a condition is false.
4 void assertNotNull(Object object)
Checks that an object isn't null.
5 void assertNull(Object object)
Checks that an object is null.
6 void assertSame(object1, object2)
The assertSame() method tests if two object references point to the same object.
7 void assertNotSame(object1, object2)
The assertNotSame() method tests if two object references do not point to the same object.
8 void assertArrayEquals(expectedArray, resultArray);
The assertArrayEquals() method will test whether two arrays are equal to each other.
Let's use some of the above-mentioned methods in an example. Create a java class file named TestAssertions.java in C:\>JUNIT_WORKSPACE.
import static org.junit.Assert.*;
public class TestAssertions {
@Test
public void testAssertions() {
//test data
String str1 = new String ("abc");
String str2 = new String ("abc");
String str3 = null;
String str4 = "abc";
String str5 = "abc";
int val1 = 5;
int val2 = 6;
String[] expectedArray = {"one", "two", "three"};
String[] resultArray = {"one", "two", "three"};
//Check that two objects are equal
assertEquals(str1, str2);
//Check that a condition is true
assertTrue (val1 < val2);
//Check that a condition is false
assertFalse(val1 > val2);
//Check that an object isn't null
assertNotNull(str1);
//Check that an object is null
assertNull(str3);
//Check if two object references point to the same object
assertSame(str4,str5);
//Check if two object references not point to the same object
assertNotSame(str1,str3);
//Check whether two arrays are equal to each other.
assertArrayEquals(expectedArray, resultArray);
}
}
Next, create a java class file named TestRunner.java in C:\>JUNIT_WORKSPACE to execute test case(s).
import org.junit.runner.Result;
import org.junit.runner.notification.Failure;
public class TestRunner2 {
public static void main(String[] args) {
Result result = JUnitCore.runClasses(TestAssertions.class);
for (Failure failure : result.getFailures()) {
System.out.println(failure.toString());
}
System.out.println(result.wasSuccessful());
}
}
Compile the Test case and Test Runner classes using javac.
C:\JUNIT_WORKSPACE>javac TestAssertions.java TestRunner.java
Now run the Test Runner, which will run the test case defined in the provided Test Case class.
C:\JUNIT_WORKSPACE>java TestRunner
Verify the output.
true
Annotation :-
Annotations are like meta-tags that you can add to your code, and apply them to methods or in class. These annotations in JUnit provide the following information about test methods −
- which methods are going to run before and after test methods.
- which methods run before and after all the methods, and.
- which methods or classes will be ignored during the execution.
The following table provides a list of annotations and their meaning in JUnit −
Sr.No. Annotation & Description
1 @Test
The Test annotation tells JUnit that the public void method to which it is attached can be run as a test case.
2 @Before
Several tests need similar objects created before they can run. Annotating a public void method with @Before causes that method to be run before each Test method.
3 @After
If you allocate external resources in a Before method, you need to release them after the test runs. Annotating a public void method with @After causes that method to be run after the Test method.
4 @BeforeClass
Annotating a public static void method with @BeforeClass causes it to be run once before any of the test methods in the class.
5 @AfterClass
This will perform the method after all tests have finished. This can be used to perform clean-up activities.
6 @Ignore
The Ignore annotation is used to ignore the test and that test will not be executed.
Create a java class file named JunitAnnotation.java in C:\>JUNIT_WORKSPACE to test annotation.
import org.junit.AfterClass;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Ignore;
import org.junit.Test;
public class JunitAnnotation {
//execute before class
@BeforeClass
public static void beforeClass() {
System.out.println("in before class");
}
//execute after class
@AfterClass
public static void afterClass() {
System.out.println("in after class");
}
//execute before test
@Before
public void before() {
System.out.println("in before");
}
//execute after test
@After
public void after() {
System.out.println("in after");
}
//test case
@Test
public void test() {
System.out.println("in test");
}
//test case ignore and will not execute
@Ignore
public void ignoreTest() {
System.out.println("in ignore test");
}
}
Next, create a java class file named TestRunner.java in C:\>JUNIT_WORKSPACE to execute annotations.
import org.junit.runner.Result;
import org.junit.runner.notification.Failure;
public class TestRunner {
public static void main(String[] args) {
Result result = JUnitCore.runClasses(JunitAnnotation.class);
for (Failure failure : result.getFailures()) {
System.out.println(failure.toString());
}
System.out.println(result.wasSuccessful());
}
}
Compile the Test case and Test Runner classes using javac.
C:\JUNIT_WORKSPACE>javac JunitAnnotation.java TestRunner.java
Now run the Test Runner, which will run the test case defined in the provided Test Case class.
C:\JUNIT_WORKSPACE>java TestRunner
Verify the output.
in before class
in before
in test
in after
in after class
true