@beforeclass methods get executed in same thread if we put parallel="tests" in the suite xml

I have a test suite where I am using parallelism by using annotation like :

test name="All Regular Tests" parallel="tests" thread-count="30"

Now, let's say we have multiple @test annotation in one class. and it has @beforeclass annotation method as well. So when separate thread will pick the tests from same class, will it execute the @beforeclass methods in both threads or will it share the same data.

Or shall I use parallel="methods", what is the correct way ?

Not able to understand the concept of parallelism.

Solution

I can see why you are confused.

It makes no sense to use parallel="tests" in the test tag. parallel="tests" is dictating that all the defined in the XML are run in different threads. But you are assigning that to a test level, so it will only apply that option for that test.

You have two options here.

To put the multithreading option at a suite level, with the "tests" parallelization: <suite name = "ParallelTesting" parallel="tests" thread-count="2">

Or to put it on the test level, with "method" option: <test name = "Test Parallelism" parallel="method" thread-count="2">

So:

"tests": for each in the XML file.
"method": for each @Test method in wherever you put the property (all the @Tests in the suite, all the @Tests in a class, etc.)

Regarding yout second question, no, it will run the @BeforeClass only once. You can put it to the test very easily:

XML File: parallel=tests on suite level:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd" >

<suite name = "ParallelTesting" parallel="tests" thread-count="2">

    <test name = "Test Parallelism 1" >
        <classes>
            <class name = "com.test.testing.test.TestClass"/>
        </classes>
    </test>

    <test name = "Test Parallelism 2" >
        <classes>
            <class name = "com.test.testing.test.TestClass2"/>
        </classes>
    </test>

</suite>

Test Class 1:

public class TestClass {

    @BeforeClass
    public void beforeClass() {
        System.out.println("Class 1 - Before Class with Thread Id:- "+ Thread.currentThread().getId());
    }

    @Test
    public void testA() {
        System.out.println("Class 1 - Test Case A with Thread Id:- " + Thread.currentThread().getId());
    }

    @Test
    public void testB() {
        System.out.println("Class 1 - Test Case B with Thread Id:- " + Thread.currentThread().getId());
    }

}

Test Class 2:

public class TestClass2 {

    @BeforeClass
    public void beforeClass() {
        System.out.println("Class 2 - Before Class with Thread Id:- "+ Thread.currentThread().getId());
    }

    @Test
    public void testA() {
        System.out.println("Class 2 - Test Case A with Thread Id:- " + Thread.currentThread().getId());
    }

    @Test
    public void testB() {
        System.out.println("Class 2 - Test Case B with Thread Id:- " + Thread.currentThread().getId());
    }

}

Output:

Class 1 - Before Class with Thread Id:- 12
Class 2 - Before Class with Thread Id:- 13
Class 2 - Test Case A with Thread Id:- 13
Class 1 - Test Case A with Thread Id:- 12
Class 2 - Test Case B with Thread Id:- 13
Class 1 - Test Case B with Thread Id:- 12

===============================================
ParallelTesting
Total tests run: 4, Failures: 0, Skips: 0
===============================================

The two other variations of parallelization are (using the same classes above):

XML File: parallel=method on suite level:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd" >

<suite name = "ParallelTesting2" parallel="methods" thread-count="2">

    <test name = "Test Parallelism 1" >
        <classes>
            <class name = "com.test.testing.test.TestClass"/>
        </classes>
    </test>

    <test name = "Test Parallelism 2" >
        <classes>
            <class name = "com.test.testing.test.TestClass2"/>
        </classes>
    </test>

</suite>

Output:

Class 1 - Before Class with Thread Id:- 12
Class 1 - Test Case B with Thread Id:- 13
Class 1 - Test Case A with Thread Id:- 12
Class 2 - Before Class with Thread Id:- 14
Class 2 - Test Case A with Thread Id:- 14
Class 2 - Test Case B with Thread Id:- 15

XML File: parallel=method on test level:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd" >

<suite name = "ParallelTesting2" >

    <test name = "Test Parallelism 1" parallel="methods" thread-count="2">
        <classes>
            <class name = "com.test.testing.test.TestClass"/>
        </classes>
    </test>

    <test name = "Test Parallelism 2" parallel="methods" thread-count="2">
        <classes>
            <class name = "com.test.testing.test.TestClass2"/>
        </classes>
    </test>

</suite>

Output:

Class 1 - Before Class with Thread Id:- 12
Class 1 - Test Case A with Thread Id:- 12
Class 1 - Test Case B with Thread Id:- 13
Class 2 - Before Class with Thread Id:- 14
Class 2 - Test Case B with Thread Id:- 15
Class 2 - Test Case A with Thread Id:- 14

And finally, what I mention it wouldn't make sense to do:

XML File: parallel=tests on test level:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd" >

<suite name = "ParallelTesting2" >

    <test name = "Test Parallelism 1" parallel="tests" thread-count="2">
        <classes>
            <class name = "com.test.testing.test.TestClass"/>
        </classes>
    </test>

    <test name = "Test Parallelism 2" parallel="tests" thread-count="2">
        <classes>
            <class name = "com.test.testing.test.TestClass2"/>
        </classes>
    </test>

</suite>

Output:

Class 1 - Before Class with Thread Id:- 1
Class 1 - Test Case A with Thread Id:- 1
Class 1 - Test Case B with Thread Id:- 1
Class 2 - Before Class with Thread Id:- 1
Class 2 - Test Case A with Thread Id:- 1
Class 2 - Test Case B with Thread Id:- 1

As you can see in that last example, everything runs on the same thread because you are asking to each test (group of methods) to run tests in parallel.