Writing Test Coverage for Else

Question

I am struggling with covering this if-else conditional.

public void pullIDAnalyticsReportAPEX() {
    crsUpdate(); 
    generateJSON();
}
public String generateJSON() {
    currentPgId = ApexPages.currentPage().getParameters().get('id');
    serializedData = new List<Contact>();
    credRevId = new List<Credit_Review__c>();
    homeAddress1 = new List<FPC_Address__c>();
    guarantorId1 = [SELECT PG1__c FROM Credit_Review__c WHERE Id = :currentPgId].PG1__c;

    if (guarantorID1 == NULL) {
        String nulLReturn = 'Null Data';
        return nullReturn;
    } 
    else {
        credRevId = [SELECT Id FROM Credit_Review__c WHERE Id = :currentPgId];
        serializedData = [SELECT Id, FirstName, LastName, Birthdate, SSN_Encrypted__c, SSN__c, MailingAddress, HomePhone, MobilePhone, Email FROM Contact WHERE Id = :guarantorId1];
        homeAddress1 = [SELECT Address_1__c, City__c, State__c, Zip_Code__c FROM FPC_Address__c WHERE Location_Type__c = 'Home Address' AND Contact__r.Id = :guarantorId1 ORDER BY CreatedDate DESC LIMIT 1];

        jk = new AccountWrapper(serializedData[0], credRevId[0], homeAddress1[0]);
        NewJSONString = JSON.serialize(jk);
        return NewJSONString;
    }
}

I am able to get through the if statement but not the else part. I have tried defining guarantorID1 with a hard coded value, queried for the ID, pulled it from a test contact, system.aserts, and other variations of these. In my test class I created an account, an opportunity, a credit review, a contact and tied all of these together. It is to my understanding that when you create a test-contact, it will be assigned an ID. I don't understand why I can't assign the contact ID as the PG1__c ID like so:

@isTest
static testmethod void firstTestAccount(){
    //no PG1__c ID
    Account a = new Account(Name = 'Test Account');
    insert a;
    Opportunity o = new Opportunity(AccountId = a.Id, Name = 'IDAnalyticsName', CloseDate = Date.today(), StageName = 'Prospecting');
    insert o;
    Contact c = new Contact(FirstName = 'FirstTest', LastName='LastTest', SSN_Encrypted__c ='000000000', HomePhone='7894561333', MobilePhone='9885556666', Email='[email protected]', AccountId = a.Id);
    insert c;
    system.debug('this is the contact ID:' + c.Id); 
    Credit_Review__c cr = new Credit_Review__c(Account__c = a.Id, Opportunity__c = o.Id); //**NOTE- THERE IS NO PG1__C IN HERE this is how I am able to get through the first part of the conditional**
    insert cr;
    system.debug('this is cr.id' + cr.Id);
    Consumer_Risk_Summary__c crs = new Consumer_Risk_Summary__c(Error_Message__c = 'ID Analytics encountered an error while processing the request.', Credit_Review__c = cr.Id);
    insert crs;
    system.debug('this is crs credit review' + crs.Credit_Review__c);

    //PG1__c ID is available
    Account a2 = new Account(Name = 'Test Account 123');
    insert a2;
    Opportunity o2 = new Opportunity(AccountId = a2.Id, Name = 'IDAnalyticsName22', CloseDate = Date.today(), StageName = 'Prospecting');
    insert o2;
    Contact c2 = new Contact(FirstName = 'FirstTest22', LastName='LastTest22', SSN_Encrypted__c ='000000000', HomePhone='7894561333', MobilePhone='9885556666', Email='[email protected]', AccountId = a2.Id);
    insert c2;
    system.debug('this is the contact ID:' + c.Id);
    Credit_Review__c cr2 = new Credit_Review__c(Account__c = a.Id, Opportunity__c = o.Id, PG1__c = c2.Id); //**NOTE THERE IS A PG1__C IN THIS CREDIT REVIEW which should allow me to enter into the second half of the if/else**
    insert cr2;
    system.debug('this is cr.id2' + cr2.Id);
    Id guarantorId1 = [SELECT PG1__c FROM Credit_Review__c WHERE Id = :cr2.Id].PG1__c;
    system.assertNotEquals(null, guarantorId1);
    Consumer_Risk_Summary__c crs2 = new Consumer_Risk_Summary__c(Credit_Review__c = cr2.Id);
    insert crs2;
    system.debug('this is crs credit review' + crs2.Credit_Review__c); 
}

Answer 1

None of the data you set matters during the test when you are basing the query:

guarantorId1 = [SELECT PG1__c FROM Credit_Review__c WHERE Id = :currentPgId].PG1__c;

On the currentPgId

currentPgId = ApexPages.currentPage().getParameters().get('id');

in fact, I do not understand how the query is not throwing an error (List has no rows for assignment to SObject) as currentPgId is null and you are attempting to pull a field from it

To set the value according to the code you have posted you need to set the Id URL parameter for the current page reference

PageReference pr = Page.[YOURPAGENAME];
pr.getParameters().put('id', guarantorId1);
test.setCurrentPage(pr);

Then when your test executes it will have the appropriate parameters set and get the correct record and enter the else