Test class in salesforce

Why we require a test class in Salesforce?

• When we are moving code from sandbox to production org we need to write test class.
• Whatever code we have written we need to ensure that each and every case is correct and we can create a dummy data for it.
• The code must have 75% coverage to deploy it to production.

Points to remember.

• As every organization have code limit by writing @isTest above test class, the limit will not be considered.
• Every test class has a method declared with testmethod keyword and is static.   

              Syntax: static testmethod void methodname()

                             {

                              }         

• Test class does not have access to organization data but if we write @isTest(seeAllData=true),then we can access data in the test class as well.

• If we are defining a test class with @isTest(SeeAllData=true) then we can access data in test class from database under all method present in test class.Under this case annoting a method with @isTest(SeeAllData=false) would be ignored and you can access database data inside this method as well. 

• If we are defining a test class with @isTest(SeeAllData=false) then we cannot access data in test class from database under all method present in test class.Under this case annoting a method with @isTest(SeeAllData=true) would not be ignored and you can access database data inside this method. 

• Test.starttest() and Test.stoptest are standard method available with test class.

• Whatever test we are performing we write the test inside of Test.starttest() and Test.stoptest, Basically they help to create fresh set of governing limit.

• Each test method can call start test and stop test only once.

• @testSetup is used to create test records and we can use this records in test methods in same test class, No need to create records multiple times in different methods.

• test.isRunningtest() is used to bypass condition in apex class if we are not able to satisfy certain if conditions in apex class.

• operation done on the records from @testSetup are local to that test method only in test class.

TEST CLASS BEST PRACTISES:

• We should always considered doing testing with bulk records.

• We Should test "test cases" for both positive and negative test scenario.

• Avoid using (SeeAllData=true) in test class because it might happen that the test class pass in sandbox but fails in production.

• Avoid using hardcoded is's in  test class.

• Each test method can call start test and stop test only once, but number depends on the number of test methods in test class.

Create a sample test class for below trigger.

Trigger:

trigger contactnamevalidation on Contact(before update)
{
for(contact obj:trigger.new)
{
if(obj.FirstName=='test1')
{
obj.FirstName='test2';
}

}

}

Test class for above trigger using @testSetup:

@isTest
Public class testclass
{
 @testSetup
 static void testsettingup()
 {
 contact obj=new contact();
 obj.firstname='test';
 obj.lastname='data';
 insert obj;

 }
 static testmethod void testmethodname() //No parameter inside test method
 {
 test.starttest();
 contact obj1=new contact();
 obj1=[Select id,firstname from contact where firstname='test'];

 obj1.firstname='test1';
 update obj1;
// operation done on the records from @testSetup are local to this test method only.
 test.stoptest();
 }
}

TAGS:test class in salesforce example,test class in salesforce best practices,test classes in salesforce,test class for trigger in salesforce example.