How Many Starttest() and StopTest() can I have in One Test Class?

Question

The concept of testing org is still very new to me. I don't think I fully understand it. But can I've more than one StartTest() and StopTest() in my test class as my test requires many cases to ensure my codes have coverage?

@isTest
private class TestSFParSched_Class{
   //Case1
   static testmethod1 void test() {
      test.StartTest();
      test.StopTest();

   }
   //Case2
   static testmethod2 void test() {
      test.StartTest();
      test.StopTest();

   }

}

Thanks

Answer 1

You can have one StartTest / StopTest per test method.

Each test method is executed independently. They may be on the same class but they share nothing and do not see side effects from each other.

You can have many test methods in any test class 99.9% of the time. The 0.1% allows for features like Queueable interface that currently require their own class.

There are two main use cases for StartTest / StopTest.

1. StartTest resets all governor limits. In this way you can set up your test data and still clearly determine the impact of your functionality on relevant governor limits.
2. StopTest forces asynchronous calls to execute. Using this method will allow you to guarantee an asynchronous call or batch has run.

There are also stylistic benefits; for AAA style tests (Arrange, Act, Assert) it is a great way to identify where the Act happens. This helps a reader to know what you intend to test.