360° With Test Class for Beginners #Salesforce

Here is have provided some of the basics to write perfect test class in salesforce

Here I'll explain with short snippets for the test classes
As the first one below

1:  @isTest(seeAllData=false)  
2:    private class Test_CountContactOfAccount {   
3:      //Method  
4:      static testMethod void CountContactOfAccountUnitTest() {  
5:      }  
6:    }  

(seeAllData=false)
You can set it true or false on your own, there are two condition for setting it true or false

1. If you are querying any object and fetching records from the database in the test class then set it to true as well there are few object we can't create in our test like "OpportunityLineItem" so to test with this object records, we need to query it with "seeAllData = true".

2. But if you are inserting test records of an object an then querying it in the test class, then you need to set it false otherwise test class won't be executed.


TESTING CUSTOM CONTROLLER AND STANDARD CONTROLLERr
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How to cover custom controller in the test class?
If you need to cover constructor in the test class then simply define it in the test class, like CountContactOfAccount is the name of the class, just define it in the test class as in below, it will cover you whole constructor.

1:  //Calling contructor  
2:  CountContactOfAccount controller = new CountContactOfAccount();  

How to call StandardController (ApexPages.StandardController stdController)?
If you are using standard controller in the class then you need to define it in the test class too

1:  //Insert you object that you are using in your class  
2:  Account acc = new Account(Name = 'test');  
3:  insert acc;  
4:  //Define standard controller and pass inserted object   
5:  ApexPages.StandardController stdController = new ApexPages.StandardController stdController(acc);  
6:  //Now define your controller then pass standard controller you've just defined  
7:  CountContactOfAccount controller = new CountContactOfAccount(stdController );  

TESTING WITH STATIC AND VOID METHODS
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How to call methods in the test class?
As you have seen above we have called controller , by using controller we can call static and void methods easily

So if the method is void like "public void something() {"

1:    //Calling contructor  
2:    CountContactOfAccount controller = new CountContactOfAccount();  
3:    //Calling void method  
4:    controller.something();  

But if the method is static like "public static list something() {"

then you can directly call the method no need to use deifned controller

1:    //Calling static method  
2:    CountContactOfAccount.something(listOfAccount);   

TESTING ApexPages.currentPage().getParameters().get('ID')
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In this scenario you just need to put the value in the test of the variable that you fetching from the the URL

1:  //this method will put Id in the URL in the test class  
2:  currentPageReference().getParameters().put('id', '001c384348247811');  

ASSERTS (Most Important thing for test classes)

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There as three most commonly used asserts are there shown below, use asserts to check that your method are returning the correct values or not.

1:  System.assert(pBoolean)  
2:  System.assertEquals(pANY, pANY)  
3:  System.assertNotEquals(pANY, pANY)  

TESTING ERROR MESSAGES
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If you have error message in your test class and you want to cover it in test class then use this snippet

1:  //List of Message  
2:  List msgs = ApexPages.getMessages();  
3:  //Define a boolean variable  
4:  boolean msg = false;  
5:  //Loop through the messages of the page  
6:  for(Apexpages.Message msg:msgs){  
7:  //if there is error message then set the boolean to true  
8:  if (msg.getDetail().contains(‘Search requires more characters’)) msg = true;  
9:  }  
10:  //Assert  
11:  system.assert(msg);  
12:  //Single Assert on Error Messages  
13:  System.assert(ApexPages.getMessages()[0].getDetail().contains( 'User not found with given username' ));  

I think these are the most common scenarios for the Test classes that makes some mess.

Some key points:

1. Whole orgs average code coverage should be 75%, NOT each class.
2. Each trigger must more then 0% code coverage.

Hope I've helped you
CHEERS....!!!!