I'm a novice developer, please help with writing a test class for this code.Thanks [duplicate]

Question

global class converterSchedule implements Schedulable {
    global void execute(SchedulableContext ctx) {
        List<Exchange_rate__c> exchange = [SELECT Date__c, GBP__c, USD__c, EUR__c, CAD__c 
                                           FROM Exchange_rate__c];

        converterWidgetController.requestAndResponseCurrency();
    }

}

Answer 1

You can go through Asynchronous Apex trailhead module to learn how to write test classes for Scheduled classes.

For writing a test class for scheduled class, you need to use startTest and stopTest around the System.schedule method, to ensure processing finishes before continuing your test.

For your case, your test class should be something like below

@isTest
private class converterScheduleTest {
    static testmethod void schedulerTest() {
        String CRON_EXP = '0 0 0 15 3 ? *';

        List<Exchange_rate__c> exchangeRates = new List<Exchange_rate__c>();
        // Create your test data
        Exchange_rate__c ex1 = new Exchange_rate__c();
        ex1.name= 'test';
        exchangeRates.add(ex1);

        Exchange_rate__c ex2 = new Exchange_rate__c();
        ex2.name= 'test';
        exchangeRates.add(ex2);
        insert exchangeRates;

        Test.startTest();

            String jobId = System.schedule('ScheduleJobName',  CRON_EXP, new converterSchedule());
            CronTrigger ct = [SELECT Id, CronExpression, TimesTriggered, NextFireTime FROM CronTrigger WHERE id = :jobId];
            System.assertEquals(CRON_EXP, ct.CronExpression);
            System.assertEquals(0, ct.TimesTriggered);

        Test.stopTest();
        // Add assert here to validate result
    }
}

You will have to set the values of all other fields of Exchange_Rate__c object i.e. Date__c, GBP__c, USD__c, EUR__c, CAD__c if they are referred in your code.