Salesforce Apex Test Class example for Callout or API call

SampleTestClass.cls

@IsTest public class SampleTestClass {

    @IsTest public static void Test1()
    {
      // upload a file in static resource first
        
      StaticResourceCalloutMock mock = new StaticResourceCalloutMock();
      mock.setStaticResource('SampleResource'); // name of static resourc
      mock.setStatusCode(200);
      mock.setHeader('Content-Type', 'application/json'); // change with correct content type
          
      // Set the mock callout mode
      Test.setMock(HttpCalloutMock.class, mock);
              
      // start execute function/method that using callout execution like API call etc
    }
}