Test.isRunningTest()

Test.isRunningTest() This is not used in test classes but in other classes in order to verify if the call is from a test class.

When we are setting up test data from Apex test method, we need a way to disable the triggers that will fire. It might cause "LimitException: "Too many SOQL queries: 101".  In this case, the triggers are not the target of the test case, hence this scenario will cause the test method to fail

Setup up the trigger by leveraging isRunningTest(). isRunningTest() - Returns true if the currently executing code was called by code contained in a test method, false otherwise. Use this method if you need to run different code depending on whether it was being called from a test.

if(Test.isRunningTest()){

//do something

}

Other Usage scenarios

1. To ensure the trigger doesn't execute the batch if Test.IsRunningTest() is true, and then test the batch class with it's own test method.

2. Testing callouts - in your callout code you check to see if you're executing within a unit test context by checking Test.isRunningTest() and instead of getting your callout response from an HttpResponse.send() request, you return a pre-built test string instead.