To get started, let's set up the Ballerina package to run tests.

1. Create a Ballerina package with the bal new command as follows.

   $ bal new hello_world
   

2. Create a directory in the root directory of the package named tests in which the test files will be stored.

   hello_world/
       Ballerina.toml
       main.bal
       tests/
           main_test.bal
   

3. Create the following function in the main.bal file.

   public function intAdd(int a, int b) returns int {
       return a + b;
   }

4. In the main_test.bal file, make use of the test module to test out the functionality of the intAdd function in the main.bal file.

   import ballerina/test;
   
   @test:Config
   function intAddTest() {
       test:assertEquals(intAdd(1, 3), 4);
   }

5. Execute the tests using the following command.

   $ bal test
   

   Then you can see the output as follows.

   Compiling source
        user/hello_world:0.1.0
   
   Running Tests
   
           hello_world
   
   
                   1 passing
                   0 failing
                   0 skipped