need help on how to achieve 100% in the test class

Question

I have been trying to write test class for 100% coverage. I have difficulty in understanding how to call the standard controller and call the parameterised constructor also set the page to the current page as the current page. On the account view page, I have overridden the new button on the related list of a custom object. I am able the use the same class when I edit the record. On both the edit record view page and the new record view page I am able to retrieve the account id. Currently I am able achieve 65% coverage. I am not sure what am I doing wrong. Please help if possible. I have attached the code below.

Thanks Gayatri

//my Class

public class NewTaxExempt{

    public TaxExempt__c obj {get; set;}   
    public String selectedIso {get;set;}

    public List<selectOption> isoCodes {

        get {
            List<selectOption> options = new List<selectOption>();

            for (State__c iso : State__c.getAll().values())
            options.add(new SelectOption(iso.State_ISO__c,iso.State_Name__c+' - '+iso.State_ISO__c));

            return options;

        }

        set;
    }

    // onload standard controller will be called.
    public NewTaxExempt(ApexPages.StandardController controller) {

        ID idte=controller.getRecord().id;
        if(idte==null){
            obj=(TaxExempt__c)controller.getRecord();
        }
        else{
            obj= [Select Account__c, Certificate_ID__c, Certificate_Type__c,Description__c, Issuing_Jurisdiction__c,Status__c,Tax_Exempt_Effective_Date__c,Tax_Exempt_Expiration_Date__c from TaxExempt__c where id=:idte];         
        }


    }

    //on click on cancel button
    public PageReference cancel() {
        return new PageReference('/'+obj.account__c);
    } 

    //on click on Save button
    public PageReference save() {

        obj.Issuing_Jurisdiction__c=selectedIso;
        if(obj.id==null){        
            insert obj;
        }
        else{
            update obj;
        }
        return new PageReference('/'+obj.account__c);
    }
}
//my test class

@isTest
public class NewTaxExemptTest{

    public static testMethod void whenIssueJurisdictionIsBlankDefaultValueIsSet(){

        try{    

            BET_ObjectFactory.generateTaxExemptRequirements();
            Account aobj = ( Account)TestFactory.createSObject(new Account(Name='test acc gs250144'),true);
            PageReference ref = Page.NewTaxExempt;
            Test.setCurrentPage(ref);
            TaxExempt__c obj=new TaxExempt__c();
            obj.account__c=aobj.Id;
            obj.Issuing_Jurisdiction__c='RI';
            ApexPages.StandardController sc = new ApexPages.StandardController(obj);
            NewTaxExempt ob=new NewTaxExempt(sc);
            ob.selectedIso='RI'; 
            ob.obj=obj; 

            ob.save(); 

            System.assertEquals(obj.Issuing_Jurisdiction__c,null);


        List<State__c> stList=new List<State__c>();

        State__c st=new State__c();
        st.Name='ST_11009';        
        st.State_Name__c='Alabama';
        st.State_ISO__c='AL';
        st.State_Country_Name__c='United States';
        st.State_Country_ISO__c='US';
        stList.add(st);

        State__c st1=new State__c();
        st1.Name='ST_11008';
        st1.State_Name__c='Alabama';
        st1.State_ISO__c='AL';
        st1.State_Country_Name__c='United States';
        st1.State_Country_ISO__c='US';
        stList.add(st1);

        State__c st2=new State__c();
        st2.Name='ST_11019';        
        st2.State_Name__c='Alaska';
        st2.State_ISO__c='AK';
        st2.State_Country_Name__c='United States';
        st2.State_Country_ISO__c='US';
        stList.add(st2);

        State__c st3=new State__c();
        st3.Name='ST_12009';        
        st3.State_Name__c='Arizona';
        st3.State_ISO__c='AZ';
        st3.State_Country_Name__c='United States';
        st3.State_Country_ISO__c='US';
        stList.add(st3);

        State__c st4=new State__c();
        st4.Name='ST_11309';
        st4.State_Name__c='Arkansas';
        st4.State_ISO__c='AR';
        st4.State_Country_Name__c='United States';
        st4.State_Country_ISO__c='US';
        stList.add(st4);

        State__c st5=new State__c();
        st5.Name='ST_21009';        
        st5.State_Name__c='California';
        st5.State_ISO__c='CA';
        st5.State_Country_Name__c='United States';
        st5.State_Country_ISO__c='US';
        stList.add(st5);

        State__c st6=new State__c();
        st6.Name='ST_23';        
        st6.State_Name__c='California';
        st6.State_ISO__c='';
        st6.State_Country_Name__c='';
        st6.State_Country_ISO__c='';
        stList.add(st6);

        insert stList;

        List<State__c> allStates = [select State_Name__c, State_ISO__c, State_Country_Name__c, State_Country_ISO__c 
                                    from State__c
                                    order by State_Name__c];

        for(State__c stt : allStates){
            if(stt.State_ISO__c == '' || stt.State_ISO__c == null){
                ob.isoCodes.add(new SelectOption(stt.State_ISO__c, stt.State_Name__c));
            }
            else{
                ob.isoCodes.add(new SelectOption(stt.State_ISO__c, stt.State_Name__c));                
            }

        }        
        System.assertNotEquals(ob.isoCodes.size(),0);


        }catch(Exception e){

            System.debug('Gayatri exception :'+e);
        }   
    }

    public static testMethod void whenUserClicksCancel(){

        BET_ObjectFactory.generateTaxExemptRequirements();
        Account aobj = ( Account)TestFactory.createSObject(new Account(Name='test acc gs250144'),true);

        // PageReference ref = new PageReference(pageName)
        // ref.getParameters().put('TaxExempt__c',obj.Id);
        // Test.setCurrentPage(ref);

        PageReference ref = Page.NewTaxExempt;
        Test.setCurrentPage(ref);
        TaxExempt__c obj=new TaxExempt__c();
        ApexPages.StandardController sc = new ApexPages.StandardController(obj);
        NewTaxExempt ob=new NewTaxExempt(sc);
        ob.cancel();  

    }    
}

Answer 1

it's gonna be much easier if you knew what part of your code is missing in test coverage.

1. Go to developer console and run your test
2. on the bottom of the page select test tab
3. find your test from the right side (with title: Overall code coverage)
4. double click on your test

uncovered part will be in red. now try to write tests for them.

If you want to cover your class properties all you have to do is this:

@isTest static void myPropertiesTest(){

    MyClass obj = new MyClass();
    obj.myProperty = SomeValue;
    // now assert a function in you class that uses this property. 

    // an easy and dumb way is to just assert the property. 
    System.assertEquals(SomeValue, obj.myProperty);
}