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Difference between 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 execution order, @BeforeTest executes first and after that, @BeforeClass does. However, if there are multiple TestNG classes and multiple Tests inside each class, then the behaviour of these methods is noticeable.
@BeforeTest
This method will execute only once in the entire execution before calling the first @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 testing.xml file, once the execution starts, @BeforeTest method executes only once before the execution of the first @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 is equal to the number of TestNG classes to execute. As per testing.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 that those can be executed as per requirement and repeated calling could be avoided.
Key points in these differences are:
@BeforeTest method executes only once before the first @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 first but @BeforeClass methods will be executing as per the respective classes.
If all test classes extend 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
Suppose there are two TestNG classes and each class is having 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 and each class extends the common class (beforemethods) - OrderofTestExecutionInTestNG and NewTestngClass
Step 3 − Write two different @Test methods in each of these two classes - OrderofTestExecutionInTestNG and NewTestngClass.
Step 4 − Now create the testNG.xml as given below to run the two TestNG classes other than the common class.
Step 5 − Finally, run the testNG.xml or directly testNG class 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
Suppose 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 @BeforeTest methods will execute first but @BeforeClass methods will be executing as per their respective classes.
Approach/Algorithm to solve this problem
Setp 1 − Create two TestNG classes, OrderofTestExecutionInTestNG and NewTestngClass
Setp 2 − Write two different @Test methods in each of these two classes, OrderofTestExecutionInTestNG and NewTestngClass.
Setp 3 − Write different @BeforeTest methods in each of these two classes, OrderofTestExecutionInTestNG and NewTestngClass.
Setp 4 − Write different @BeforeClass methods in each of these two classes, OrderofTestExecutionInTestNG and NewTestngClass.
Setp 5 − Now create the testNG.xml as given below to run the two TestNG classes.
Setp 6 − Now, run the testNG.xml or directly testNG class 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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