Salesforce Developer – Test Classes Questions

Test Classes - Q&A

1. Q1. What are the key requirements for test classes in Salesforce?
   Ans: Core requirements: - Minimum 75% code coverage (org-wide) - Test all code paths (positive/negative) - Use @isTest annotation - No DML in class declaration - Test data isolation (no seeAllData=true unless necessary) - Assert expected outcomes - Test governor limit handling
2. Q2. Explain the Test.startTest() and Test.stopTest() methods.
   Ans: Test boundary markers: - Test.startTest(): * Resets governor limits * Marks beginning of tested code * Enables async execution in tests - Test.stopTest(): * Forces async job execution * Marks end of tested code * Restores original limits context Example:

   @isTest
   private class MyTestClass {
     @isTest static void testMethod() {
       Test.startTest();
       // Code under test
       MyClass.myMethod();
       Test.stopTest();
       // Verify results
     }
   }

3. Q3. What are the different ways to create test data?
   Ans: Test data approaches: - Direct DML: insert new Account(Name='Test'); - @testSetup: Shared data across methods - Test.loadData(): Static resource CSV - TestFactory pattern: Reusable data creation - Mocking: HttpCalloutMock, StubProvider Best practice: Create only necessary data
4. Q4. How do you mock HTTP callouts in test classes?
   Ans: HttpCalloutMock implementation:

   @isTest
   private class MockHttpResponse implements HttpCalloutMock {
     public HttpResponse respond(HttpRequest request) {
       HttpResponse response = new HttpResponse();
       response.setStatusCode(200);
       response.setBody('{"status":"success"}');
       return response;
     }
   }
   
   // In test method:
   Test.setMock(HttpCalloutMock.class, new MockHttpResponse());
   Test.startTest();
   // Code that makes callout
   Test.stopTest();

5. Q5. What is the purpose of @testSetup and when should you use it?
   Ans: @testSetup benefits: - Reduces redundant data creation - Improves test performance - Ensures data consistency - Shared across test methods Example:

   @testSetup
   static void setupTestData() {
     Account testAcc = new Account(Name='Test Account');
     insert testAcc;
     // Other shared data
   }

   Use when multiple methods need same base data
6. Q6. How do you handle test data isolation and seeAllData parameter?
   Ans: Data isolation principles: - Default: seeAllData=false (recommended) - Test data doesn't persist in org - Cannot access production records - Exception: seeAllData=true for: * Legacy orgs * Certain setup objects * External ID matching Best practice: Always use isolated test data
7. Q7. What are the best practices for assertion strategies?
   Ans: Assertion guidelines: - Use System.assert methods - Test both positive and negative cases - Assert specific values, not just existence - Use meaningful assertion messages - Verify all expected outcomes Example:

   System.assertEquals(
     'Expected Value', 
     actualValue, 
     'Field should match expected value'
   );

8. Q8. How do you test exception handling in Apex?
   Ans: Exception testing pattern:

   @isTest
   static void testExceptionHandling() {
     try {
       MyClass.processData(null); // Should throw exception
       System.assert(false, 'Expected exception not thrown');
     } catch (MyCustomException e) {
       System.assertEquals(
         'Invalid input', 
         e.getMessage()
       );
     }
   }

   Test both expected and unexpected exceptions
9. Q9. What are the governor limit considerations in testing?
   Ans: Limit management: - Test.startTest() resets limits - Monitor heap size, SOQL, DML counts - Test bulk operations (200+ records) - Verify async job limits - Check CPU time consumption Use Limits methods for monitoring:

   Integer queriesUsed = Limits.getQueries();
   System.assert(queriesUsed < 5, 'Too many queries');

10. Q10. How do you implement test factories for reusable data creation?
    Ans: Factory pattern:

    public class TestDataFactory {
      public static Account createAccount(String name) {
        Account acc = new Account(
          Name = name,
          Type = 'Customer'
        );
        insert acc;
        return acc;
      }
      
      public static List createContacts(
        Integer count, 
        Id accountId
      ) {
        List contacts = new List();
        for (Integer i = 0; i < count; i++) {
          contacts.add(new Contact(
            LastName = 'Test ' + i,
            AccountId = accountId
          ));
        }
        insert contacts;
        return contacts;
      }
    }

11. Q11. What are the security considerations for test classes?
    Ans: Security aspects: - Test with various user profiles - Verify CRUD/FLS enforcement - Test sharing rule impacts - Validate field-level security - Check for data exposure Example:

    User testUser = [SELECT Id FROM User WHERE Profile.Name='Standard User' LIMIT 1];
    System.runAs(testUser) {
      // Test with restricted user
    }

12. Q12. How do you test asynchronous code (Batch, Queueable, Future)?
    Ans: Async testing approach:

    @isTest
    static void testBatchJob() {
      // Setup test data
      Test.startTest();
      // Execute batch
      MyBatch batchJob = new MyBatch();
      ID jobId = Database.executeBatch(batchJob);
      Test.stopTest();
      
      // Verify results
      AsyncApexJob job = [SELECT Status FROM AsyncApexJob WHERE Id = :jobId];
      System.assertEquals('Completed', job.Status);
    }

13. Q13. What are common test class anti-patterns?
    Ans: Avoid these practices: - Hardcoding IDs or usernames - Testing implementation details - Ignoring negative test cases - Over-mocking external systems - Creating unnecessary test data - Asserting without meaningful messages - Using seeAllData=true unnecessarily
14. Q14. How do you measure and improve test coverage effectively?
    Ans: Coverage strategies: - Aim for 100% coverage (not just 75%) - Test all code paths - Use Developer Console coverage view - Run all tests to check overall coverage - Focus on quality over quantity - Refactor untestable code - Use code coverage tools
15. Q15. Explain real-world test class scenarios.
    Ans: Practical applications: - Trigger handler testing - Web service integration testing - Complex business logic validation - Security and sharing verification - Performance boundary testing - Error handling validation - Multi-user scenario testing - Integration point validation