Compile Error: Only top-level class variables can be declared static

Question

@isTest
private class TestRejectDoubleBooking{
    public void TestSingleBooking(){
      static testmethod void TestSingleBooking() {
    Datetime now = System.now();

    Speaker__c speaker = new Speaker__c(First_Name__c='John', Last_Name__c='Smith');
    insert speaker;

    Session__c session = new Session__c(Name='Some Session', Session_Date__c=now);
    insert session;

    Session_Speaker__c assignment =
    new Session_Speaker__c(Session__c=session.Id, Speaker__c=speaker.Id);

    Database.SaveResult result = Database.insert(assignment, false);

    System.assert(result.isSuccess());
}   
    }

}

Answer 1

You cannot declare a method within a method. Remove this line:

public void TestSingleBooking() {

And also remove the corresponding closing bracket }.

Correct Code:

@IsTest
class TestRejectDoubleBooking
{
    static testMethod void testSingleBooking()
    {
        // test code here
    }
}

What you are doing instead is trying to declare a method within a method, as stated above. Note also that your methods must be declared testmethod or annotated with @IsTest in order to actually run.

Incorrect Code:

@IsTest
class TestRejectDoubleBooking
{
    public void testSingleBooking()
    {
        static testMethod void testSingleBooking()
        {
            // test code here
        }
    }
}

I also find that careful, consistent use of indentation can make these types of problems much more clear.