how to cover code for catch block?

Question

public  class  QMT_ReviewSubmit {
public static QMT_Apex_Debug_Logs__c logger = new QMT_Apex_Debug_Logs__c(Apex_Class__c = 'QMT_ReviewSubmit', Type__c = 'UI');
public static String QMTThumbnail = System.Label.QMT_Thumbnail;
public static  String QMTcontentimage = System.Label.QMT_Content;
public static String QMTVideolink = System.Label.QMT_Video_link;
public static String editorProfile = System.Label.Commn_QMTEditor;
// Added by Shankar on Mar 06 2018 
public static QMT_Content__c QMTContent;

@AuraEnabled
public static Contact getCurrentUser(){
    user CurrentuserforSender = null;
    Contact USerAsContacts = null;
    try {
        CurrentuserforSender = [select Id, Username, Email, Name from User where Id = : UserInfo.getUserId()];
        USerAsContacts = [SELECT Id, Name, LastName, Email from Contact where Email  =: CurrentuserforSender.Email];
    } catch (QueryException ex) {
        insert new QMT_Apex_Debug_Logs__c(Apex_Class__c = 'QMT_ReviewSubmit', Type__c = 'UI',
                Message__c       = System.Label.QMT_Database_SOQL_Failure,
                Method__c        = 'getCurrentUser',
                Stack_Trace__c   = ex.getStackTraceString());
    }
    return USerAsContacts;
}

Test Class:

        @isTest
    public class QMT_ReviewSubmitTest {

        static  testMethod  void test1() {

            Profile p = [SELECT Id FROM Profile WHERE Name = 'System Administrator'];
            User u = new User(Alias = 'asdsad', Email = '[email protected]',
                              EmailEncodingKey = 'UTF-8', LastName = 'Testing', LanguageLocaleKey = 'en_US',
                              LocaleSidKey = 'en_US', ProfileId = p.Id,
                              TimeZoneSidKey = 'America/Los_Angeles', UserName = '[email protected]');
            insert u;
            Account a = new Account();
            a.name = 'test';
            insert a;

            Contact con = new Contact();
            con.LastName = 'test'; 
            con.AccountId = a.id;
            con.FirstName = 'test';
            con.Email = '[email protected]';
            con.QMT_PersonnelNbr__c = 2.0;
            insert con;

            QMT_Content__c c = new QMT_Content__c();
            c.name = 'test';
            c.QMT_Main_Body__c = 'test1tesdt2';
            c.Featured_Image_ID__c = 'test';
            c.QMT_Primary_Title__c = 'test';
            Recordtype RecordTypeIdcomm = [Select Id, Name From RecordType where Name = 'News / Alert' limit 1];
            c.RecordTypeId = RecordTypeIdcomm.id;
            QMT_Segment__c segment = new QMT_Segment__c();
            insert segment;
            c.SegmentId__c = segment.Id;
            insert c;

            QMT_Segment_Definition__c segmentDefinition = QMT_UnitTestData.createSegmentDefinition(segment.Id);
            insert segmentDefinition;
            system.assertEquals('[email protected]', con.Email);

            List<String> allSelectedTopics = new List<String> {'test', 'test1'};
            QMT_CM_Topic_Master__c ci = new QMT_CM_Topic_Master__c();
            ci.TopicName__c = 'test';
            insert ci;

            QMT_CM_RestrictedAudience_Master__c ci2 = new QMT_CM_RestrictedAudience_Master__c();
            ci2.RAName__c = 'test';
            insert ci2;

            List<Folder> contentimagefolder   = [Select Id From Folder Where Name =: Label.QMT_Content];
            List<Folder> thumbnailimagefolder = [Select Id From Folder Where Name =: Label.QMT_Thumbnail];

            Document document = new Document();
            document.Body = Blob.valueOf('Some Text');
            document.ContentType = 'application/pdf';
            document.DeveloperName = 'QMT_ContentImage';
            document.IsPublic = true;
            document.Name = 'QMT content Image';
            if (contentimagefolder.size() > 0)
                document.FolderId = contentimagefolder[0].Id; //[select id from folder where name = 'QMT Content'].id;
            insert document;

            Document document1 = new Document();
            document1.Body = Blob.valueOf('Some Text');
            document1.ContentType = 'application/pdf';
            document1.DeveloperName = 'QMT_ThumbnailImage';
            document1.IsPublic = true;
            document1.Name = 'QMT Thumbnail Image';
            if (contentimagefolder.size() > 0)
                document1.FolderId = thumbnailimagefolder[0].id; //[select id from folder where name = 'QMT Content'].id;
            insert document1;

            QMT_Content_Topic_Jun__c CTopicJun = new QMT_Content_Topic_Jun__c(CM_Topic_Name__c = ci.Id, CommunicationContentName__c = c.Id);
            insert CTopicJun;
            // Recordtype RecordTypeIdcomm =[Select Id,Name From RecordType where Name='News / Alert' limit 1];

            String date1 = '2018-05-14T07:00:00.000Z'; 
            String date2 = 'May 14, 2018 7:00:00 AM';

            system.runAs(u) {
                  try{
                    Test.startTest();
                    QMT_ReviewSubmit QMT = new QMT_ReviewSubmit();
                    QMT_ReviewSubmit.getCurrentUser();
                     Test.stopTest();
               } catch (DmlException e) {
                }
            }
        }

Test class is passing but catch block is not covering? Can any one suggest me how to do that?

} catch (QueryException ex) {
        insert new QMT_Apex_Debug_Logs__c(Apex_Class__c = 'QMT_ReviewSubmit', Type__c = 'UI',
                Message__c       = System.Label.QMT_Database_SOQL_Failure,
                Method__c        = 'getCurrentUser',
                Stack_Trace__c   = ex.getStackTraceString());
    }

Answer 1

System.QueryException: List has no rows for assignment to SObject

This happens when the Object you are querrying does not meet criteria and returns 0 rows.

CurrentuserforSender = [select Id, Username, Email, Name from User where Id = : UserInfo.getUserId()];
USerAsContacts = [SELECT Id, Name, LastName, Email from Contact where Email  =: CurrentuserforSender.Email];

Thus one for the line from the above 2 should not return any rows for this exception to occur.

Lets consider line 1:

[select Id, Username, Email, Name from User where Id = : UserInfo.getUserId()];

This will always return row /records as there will always be a running user.

For the second line, a query on Contact. You need to write a test class which would make that querry fail. ie Contact's emailID and User's email id should not be same.(Or best no contact to be present)

 static  testMethod  void testCatchBlock() {
        boolean isExceptionCovered=false;
        Profile p = [SELECT Id FROM Profile WHERE Name = 'System Administrator'];
        User u = new User(Alias = 'asdsad', Email = '[email protected]',
                          EmailEncodingKey = 'UTF-8', LastName = 'Testing', LanguageLocaleKey = 'en_US',
                          LocaleSidKey = 'en_US', ProfileId = p.Id,
                          TimeZoneSidKey = 'America/Los_Angeles', UserName = '[email protected]');
        insert u;
        try{
            System.runAs(u){
                 QMT_ReviewSubmit.getCurrentUser();

            }
        }catch(Exception e){
            System.assertEquals(e instanceOf QueryException)
        }
        System.assert(isExceptionCovered,'Opps exception was not covered')

 }

Answer 2

Looking at your code, it is quite simple to provoke the exception there, just create another Contact with the same email address in your test data, this will throw a query exception since you're casting the query to a single instance of contact (and not a list).

I would advise you to write two tests:

• One for the passing context
• Another for the not passing context

i.e. you can call them that way:

• getCurrentUserPassTest
• getCurrentUserFailTest

Your first test will pass with your current code, you just need to create another that replicates the first with a second Contact, and verify that the error is thrown/your log is inserted.

With that said, you should consider creating your common test data in a @TestSetup markup, then create test-specific data in each test.

Answer 3

The golden rule of unit testing is you only gain coverage for code that is executed as part of a unit test. The most important part of unit testing is to verify the behavior of your code using assertions.

To gain coverage for a catch block, you need to cause an appropriate exception to be thrown in the try block.

In this particular case, causing a System.QueryException is pretty easy, and Pranay's answer will do the trick. Sometimes, however, it's not so easy (how can you ensure that a System.DMLException would be thrown?).

One general approach that can be taken (to ensure that pretty much any exception can be thrown) is to use a static variable to control entry into a special if() block.

// This probably isn't great practice, but making the static var private
//   keeps other people/code from messing around with the value.
// The "@testVisible" annotation makes a variable (even a private one)
//   available to be read/written in a test.
@testVisible
private static Boolean induceException = false;

@AuraEnabled
public static Contact getCurrentUser(){
    user CurrentuserforSender = null;
    Contact USerAsContacts = null;
    try {
        // Since this is a static method, we can access static class variables
        // Since our variable is a boolean, there is no need to explicitly test 
        //   boolean == true.
        if(induceException){
            throw new System.QueryException('test exception');
        }

        CurrentuserforSender = [select Id, Username, Email, Name from User where Id = : UserInfo.getUserId()];
        USerAsContacts = [SELECT Id, Name, LastName, Email from Contact where Email  =: CurrentuserforSender.Email];
    } catch (QueryException ex) {
        insert new QMT_Apex_Debug_Logs__c(Apex_Class__c = 'QMT_ReviewSubmit', Type__c = 'UI',
                Message__c       = System.Label.QMT_Database_SOQL_Failure,
                Method__c        = 'getCurrentUser',
                Stack_Trace__c   = ex.getStackTraceString());
    }
    return USerAsContacts;
}

The test method for testing the catch block would be pretty simple

@isTest 
static void testCatchBlock(){
    QMT_ReviewSubmit testInstance = new QMT_ReviewSubmit();

    QMT_ReviewSubmit.induceException = true;

    Contact result;
    test.startTest();
    result = testInstance.getCurrentUser();
    test.stopTest();

    // Don't forget to make assertions!
    // Good assertions to make would be checking that the return value
    //   is what you expect it to be, and that you did successfully create
    //   a QMT_Apex_Debug_Logs__c record
}

One thing to keep in mind is that you can have more than one test method in a test class. In fact, I'd argue that you should have more than one test method. By breaking your test scenarios apart, so that each test method covers a single scenario, you'll probably find that the individual test methods are easier to write. Also, if one of your test methods fails, you'll have a much better idea of precisely what needs to be fixed (compared to mashing everything into a single test method).