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What is the priority of BeforeClass and BeforeTest methods in TestNG?
A TestNG class can have various TestNG methods such as @BeforeTest, @AfterTest, @BeforeSuite, @BeforeClass, @BeforeMethod, @test, etc. As per the execution order, @BeforeTest executes first and after that @BeforeClass does. However, if there are multiple TestNG classes and multiple Tests inside each class, the behaviour of these methods is noticeable.
@BeforeTest
This method will execute only once in the entire execution before calling the 1st @Test method. It doesn't matter how many @Test tags are present or how many classes are there having @Test tags, or multiple classes have multiple test tags. Based on the testNG.xml file, once the execution starts, the @BeforeTest method executes only once before the execution of the 1st @Test method and @BeforeClass as well as @BeforeMethod if present.
@BeforeClass
This method will execute once per class, i.e., the number of executions of @BeforeClass = Number of TestNG class to execute. As per testNG.xml, if 10 TestNG classes are supposed to execute, then @BeforeClass will execute each time before each class starts running. It doesn't matter how many @Test tags are present inside each class.
As per best practices, it is always advisable to create a separate class for all the common @Before methods, so those can be executed as per requirement and repeated calling could be avoidable.
Key points in these two methods are −
@BeforeTest method executes only once before the 1st @Test method.
@BeforeClass executes before each class.
If there are separate @BeforeTest and @BeforeClass methods in different classes, then all the @BeforeTest methods will execute 1st, but @BeforeClass methods will be executing as per their respective classes.
If all the test classes extend the common @BeforeTest and @BeforeClass methods present in a separate class, then @BeforeTest will execute only once; however the same @BeforeClass method will execute before each class.
Scenario 1
When there are two TestNG classes and each class has two @Test tags. Each class extends the common class having @BeforeTest and @BeforeClass method inside it. In this scenario, @BeforeTest will execute only once, however the same @BeforeClass method will execute twice, each time before each class.
Approach/Algorithm to solve this problem −
Step 1 − Create a common TestNG class "beforemethods" and write the @BeforeTest and @BeforeClass methods.
Step 2 − Create two TestNG classes (OrderofTestExecutionInTestNG and NewTestngClass) and let each class extend the common class (beforemethods).
Step 3 − Write two different @Test methods in each of these two classes.
Step 4 − Now create the testNG.xml as given below to run the two TestNG classes other than the common class.
Step 5 − Run the testNG.xml or run the testNG class directly in IDE or compile and run it using command line.
Example
Use the following code for the common TestNG class "beforemethods" −
import org.testng.annotations.BeforeClass;
import org.testng.annotations.BeforeTest;
public class beforemethods {
@BeforeClass
public void beforeClass() {
System.out.println("in beforeClass");
}
@BeforeTest
public void beforeTest() {
System.out.println("in beforeTest");
}
}Use the following code for the TestNG class "OrderofTestExecutionInTestNG" −
import org.testng.annotations.Test;
public class OrderofTestExecutionInTestNG extends beforemethods {
// test case 1
@Test
public void testCase1() {
System.out.println("in test case 1 of OrderofTestExecutionInTestNG");
}
// test case 2
@Test
public void testCase2() {
System.out.println("in test case 2 of OrderofTestExecutionInTestNG");
}
}Use the following code for the common TestNG class "NewTestngClass" −
import org.testng.annotations.Test;
public class NewTestngClass extends beforemethods{
@Test
public void testCase1() {
System.out.println("in test case 1 of NewTestngClass");
}
@Test
public void testCase2() {
System.out.println("in test case 2 of NewTestngClass");
}
}testNG.xml
This is a configuration file that is used to organize and run the TestNG test cases. It is very handy when limited tests are needed to execute rather than the full suite.
<?xml version = "1.0" encoding = "UTF-8"?> <!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd" > <suite name = "Suite1"> <test name = "test1"> <classes> <class name = "OrderofTestExecutionInTestNG"/> <class name = "NewTestngClass"/> </classes> </test> </suite>
Output
in beforeTest in beforeClass in test case 1 of OrderofTestExecutionInTestNG in test case 2 of OrderofTestExecutionInTestNG in beforeClass in test case 1 of NewTestngClass in test case 2 of NewTestngClassin afterSuite
Scenario 2
When there are two TestNG classes and each class is having two @Test tags and separate @BeforeTest as well as @BeforeClass methods.
In this scenario, all the @BeforeTest methods will execute first, but the @BeforeClass methods will be executing as per their respective classes.
Approach/Algorithm to solve this problem −
Step 1 − Create two TestNG classes: OrderofTestExecutionInTestNG and NewTestngClass
Step 2 − Write two different @Test methods in each of these two classes.
Step 3 − Write different @BeforeTest methods in each of these two classes.
Step 4 − Write different @BeforeClass methods in each of these two classes.
Step 5 − Now create the testNG.xml as given below to run the two TestNG classes.
Step 6 − Run the testNG.xml or run the testNG class directly in IDE or compile and run it using command line.
Example
Use the following code for the TestNG class "OrderofTestExecutionInTestNG" −
import org.testng.annotations.Test;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.BeforeTest;
public class OrderofTestExecutionInTestNG {
// test case 1
@Test
public void testCase1() {
System.out.println("in test case 1 of OrderofTestExecutionInTestNG");
}
// test case 2
@Test
public void testCase2() {
System.out.println("in test case 2 of OrderofTestExecutionInTestNG");
}
@BeforeClass
public void beforeClass() {
System.out.println("in beforeClass of OrderofTestExecutionInTestNG");
}
@BeforeTest
public void beforeTest() {
System.out.println("in beforeTest of OrderofTestExecutionInTestNG");
}
}Use the following code for the common TestNG class "NewTestngClass" −
import org.testng.annotations.Test;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.BeforeTest;
public class NewTestngClass {
@Test
public void testCase1() {
System.out.println("in test case 1 of NewTestngClass");
}
@Test
public void testCase2() {
System.out.println("in test case 2 of NewTestngClass");
}
@BeforeTest
public void beforeTest() {
System.out.println("in beforTest of NewTestngClass");
}
@BeforeClass
public void beforeClass() {
System.out.println("in beforeClass of NewTestngClass");
}
}testNG.xml
This is a configuration file that is used to organize and run the TestNG test cases. It is very handy when limited tests are needed to execute rather than the full suite.
<?xml version = "1.0" encoding = "UTF-8"?> <!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd" > <suite name = "Suite1"> <test name = "test1"> <classes> <class name = "OrderofTestExecutionInTestNG"/> <class name = "NewTestngClass"/> </classes> </test> </suite>
Output
in beforTest of NewTestngClass in beforeTest of OrderofTestExecutionInTestNG in beforeClass of OrderofTestExecutionInTestNG in test case 1 of OrderofTestExecutionInTestNG in test case 2 of OrderofTestExecutionInTestNG in beforeClass of NewTestngClass in test case 1 of NewTestngClass in test case 2 of NewTestngClassin
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