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AmberTaylorAmberTaylor 

Test Class For a Get request

Hello, 

Is someone available to help me with a test class ?

here is my code :
public class TokenGenerator_CTL {
    private static final String CNONCE = String.valueOf(Crypto.getRandomLong()); 

    //random number ;
    public String finalUrl { get; set; }

    public TokenGenerator_CTL() {
       
       
       //retrieve custom settings TokenSettings__c that contains credentials to access insideBoard Widget
       InsideboardSettings__c oIBSettings = [ SELECT PRIVATE_KEY__c, PUBLIC_KEY__c, SUBDOMAIN__c, WIDGET_PATH__c FROM TokenSettings__c LIMIT 1 ];
       System.debug('oIBSettings Value = ' + oIBSettings);
       // Get current user ID
       String userId = UserInfo.getUserId();

       // path to access the Widget and custom settings fields to retrieve keys
       String Widget_Path = '/query-auth-access/project/__/user/UID/one/time/only/to/widget/show';
       String WP = oIBSettings.WIDGET_PATH__c;
       if (!string.isBlank(WP)){ 
           Widget_Path = '/query-auth-access/project/__/user/UID/one/time/only/redirect/project/' +  WP + '/to/widget/show' ;
        }
        System.debug('WidgetPATH Value = ' + Widget_Path);

       String Client_Private = oIBSettings.PRIVATE_KEY__c; 
       String Client_Public  = oIBSettings.PUBLIC_KEY__c; 
       String Base_URL = 'https://' + oIBSettings.SUBDOMAIN__c + '.thisSite.com';
       //this allows to change UID string with retrieved userId variable value
       String path = Widget_Path.replace('UID', getUserFederationId (userId));
       // complete url
       String url = Base_URL + path;
       String strippedURL = Base_URL.removeStart('https://');
       long timestamp = Datetime.now().getTime(); String cnonce = CNONCE + timestamp;
       String tmpParamString = 'cnonce=' + EncodingUtil.urlEncode (cnonce, 'UTF-8') + '&key=' + EncodingUtil.urlEncode(Client_Public, 'UTF-8') + '&timestamp=' + timestamp/1000 ;
       String sign1 = 'GET\nhttps\n' + strippedURL + '\n'+ path.toLowerCase() + '\n' + tmpParamString;
       String paramString = tmpParamString + '&signature=' + EncodingUtil.urlEncode(getSignature(sign1, Client_Private), 'UTF-8');
       finalUrl = url + '?' + paramString;
       System.debug('<======== Final URL Value = ' + finalURL + ' ========>');
    }
    
    // function that returns signature, that will be use to get final URL 
    private static String getSignature (String toSign, String privateKey) {
     Blob signatureBlob = Crypto.generateMac('HmacSHA256', Blob.valueOf(toSign) , Blob.valueOf(privateKey));
     String signature = EncodingUtil.base64Encode(signatureBlob); 
     System.debug('Signature value = ' + signature + ' ========>');
     return signature;
    }

    // function that returns current user Federation Id
    private String getUserFederationId(String userId) {
     String federationId = [SELECT FederationIdentifier FROM User WHERE Id = :userId].FederationIdentifier;
     System.debug('<======== FederationId value = ' + federationId + ' ========>') ;
     return (federationId == null) ? '' : federationId;
    }
}

Here My starting TestClass : 
public with sharing class TokenGenerator_CTL_TST {
    @isTest public static void TestTokenGenerator() {
        Profile profileId = [SELECT Id FROM Profile WHERE Name = 'Standard User' LIMIT 1];

        User usr = new User(LastName = 'Test',
            FirstName='EML',
            Alias = 'EmlT',
            Email = 'eml.test@gmail.com',
            Username = 'eml.test@gmail.com',
            ProfileId = profileId.id,
            TimeZoneSidKey = 'GMT',
            LanguageLocaleKey = 'en_US',
            EmailEncodingKey = 'UTF-8',
            LocaleSidKey = 'en_US',
            FederationIdentifier = 'IJK435'
            );
        insert usr;

        TokenGenerator_CTL testTry = new TokenGenerator_CTL();
        
        System.runAs(usr) {
            Test.startTest();
            RestRequest req = new RestRequest(); 
            RestResponse res = new RestResponse();
            req.requestURI = testTry.finalURL; 
            req.httpMethod = 'GET';
            req.addHeader('Content-Type', 'application/json'); 
            RestContext.request = req;
            RestContext.response = res;
            Test.stopTest();   
        }
    }
}

Any help on this topic would be appreciated ! TY in advance
Amber
SwethaSwetha (Salesforce Developers) 
HI Amber,
Though not exact, the below posts give a good insight into how to begin writing test class and how coverage can be improved and should help you get started.

https://salesforce.stackexchange.com/questions/244788/how-do-i-write-an-apex-unit-test
https://salesforce.stackexchange.com/questions/244794/how-do-i-increase-my-code-coverage-or-why-cant-i-cover-these-lines 

Examples of test classes that cover Crypto.generateMac() and federationIdentifier :
https://salesforce.stackexchange.com/questions/193281/really-stuck-need-some-help-creating-apex-test-class-for-jit-class-auth-samut
https://salesforce.stackexchange.com/questions/325010/attempt-to-de-reference-a-null-object-email-service-test-class

If it helps, please mark this answer as best.Thank you