The main apex class is :-
 

public without sharing class POCPAGEV2CaseContrl {
public String siteKeyValue{get; set;}
    public boolean caseCreated{Get;set;}
    public POCPAGEV2CaseContrl(ApexPages.StandardController sc){
        caseCreated = false;
        caseVar = new Case();
        siteKeyValue = UTAGoogleRecatcha__c.getValues('GoogleRecaptchaKey').SiteKeyValue__c;
    }
    public case caseVar{Get;set;}
    public pagereference saveRec(){
            if(!isCaptchaValid()){

            ApexPages.addMessage(new ApexPages.Message(ApexPages.Severity.ERROR, 'Recaptcha validation failed'));
                    return null;
        }
    caseVar.RecordTypeId='01270000000YTjY';
        insert caseVar;
        caseCreated = true;
        return new pagereference('/apex/POCPage3Case?success=1').setRedirect(true);
    }
    
      // Simranjeet Singh - Commented this Method.
  public Boolean isCaptchaValid(){
    String gRecaptchaResponse = ApexPages.currentPage().getParameters().get('g-recaptcha-response');
        GoogleRecaptcha grecaptcha = new GoogleRecaptcha(UTAGoogleRecatcha__c.getValues('GoogleRecaptchaKey').SecretKeyValue__c);
        return grecaptcha.validCaptcha(gRecaptchaResponse);
    } 
}

The above apex class has instance of this apex class below :-
 

public class GoogleRecaptcha {
	
	private String secretKey;
	
	public GoogleRecaptcha(String secretKey){
		this.secretKey = secretKey;
	}
	
	public Boolean validCaptcha(String validationString){
		
		HttpRequest request = new HttpRequest();
		request.setMethod('POST');
		request.setEndpoint('https://www.google.com/recaptcha/api/siteverify');
		request.setBody('secret='+EncodingUtil.urlEncode(secretKey,'UTF-8')+'&response='+EncodingUtil.urlEncode(validationString, 'UTF-8'));
		
		Http http = new Http();
		HttpResponse httpResponse = http.send(request);
		
		RecaptchaResponse response = (RecaptchaResponse)JSON.deserialize(httpResponse.getBody(), RecaptchaResponse.class);
		
		return response.success;
	}
	
	public class RecaptchaResponse{
		Boolean success {get;set;}
	}

}

please help me in test class with proper code coverage for the top most class :- POCPAGEV2CaseContrl

Any Help would be appreciated. Thanks in advance.