Junit - Using Assertion
JUNIT Assertion
Assertion All the assertion 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:
S.N. Methods & Description 1 void assertEquals(boolean expected, boolean actual) Check that two primitives/Objects are equal 2 void assertTrue(boolean expected, boolean actual) Check that a condition is true 3 void assertFalse(boolean condition) Check that a condition is false 4 void assertNotNull(Object object) Check that an object isn’t null. 5 void assertNull(Object object) Check that an object is null 6 void assertSame(boolean condition) The assertSame() methods tests if two object references point to the same object 7 void assertNotSame(boolean condition) The assertNotSame() methods tests if two object references 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 try to cover all of the above mentioned methods in an example. Create a java class file name TestAssertions.java in C:\ > JUNIT_WORKSPACE
import org.junit.Test;
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, let’s create a java class file name TestRunner.java in C:\ > JUNIT_WORKSPACE to execute Test case(s)
import org.junit.runner.JUnitCore;
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 test case defined in provided Test Case class.
C:\JUNIT_WORKSPACE>java TestRunner
Verify the output.
true Annotation Annotations are like meta-tags that you can add to you code and apply them to methods or in class. These annotation in JUnit gives us information about test methods , which methods are going to run before & after test methods, which methods run before & after all the methods, which methods or class will be ignore during execution.
List of annotations and their meaning in JUnit :
S.N. 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 name JunitAnnotation.java in C:\ > JUNIT_WORKSPACE to test annotation
import org.junit.After;
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, let’s create a java class file name TestRunner.java in C:\ > JUNIT_WORKSPACE to execute annotaions
import org.junit.runner.JUnitCore;
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 test case defined in 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
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