Unit Tests for timer triggered Azure Function: provide test data

Question

To Unit Testing HTTP triggered Azure Functions with test data is well and often described. For example here: How to write unit test for azure function v1

Mock data are given in the http request.

But I have a timer triggerd Azure function which reads data from a FTP server. I would like to Unit Test the function with test data.

My function:

[FunctionName("MyTimerTriggeredFunction")]
public static void Run([TimerTrigger("0 */2 * * * *")]TimerInfo myTimer, ILogger log, ExecutionContext context)
{
    log.LogInformation($"C# Timer trigger function executed at: {DateTime.Now}");

    ServiceClass serviceClass = new ServiceClass(log, context);

    List<Order> orderList = serviceClass.getOrdersFromFtp();
...

a running Unit Test function to test the logger, just to show how I started:

public void TestLogger()
{
    // https://learn.microsoft.com/de-de/azure/azure-functions/functions-test-a-function
    var logger = (ListLogger)TestFactory.CreateLogger(LoggerTypes.List);
    MyTimerTriggeredFunction.Run(null, logger, null);
    var msg = logger.Logs[0];
    bool testString = msg.Contains("C# Timer trigger function executed at");
    Assert.IsTrue(testString);
}

serviceClass.getOrdersFromFtp() return a list of objects. I could create this list with mock data in the unit test but how to give it to the timer triggered azure function?

Answer 1

You should move your business logic outside of the azure function and test that, rather than coming up with ways to mock data for a timer-triggered function.

Your code would look something like this:

[FunctionName("MyTimerTriggeredFunction")]
public static void Run([TimerTrigger("0 */2 * * * *")]TimerInfo myTimer, ILogger log, ExecutionContext context)
{
    log.LogInformation($"C# Timer trigger function executed at: {DateTime.Now}");

    ServiceClass serviceClass = new ServiceClass(log, context);

    serviceClass.DoWork();

...

class ServiceClass
{
    public void DoWork()
    {        
         List<Order> orderList = serviceClass.getOrdersFromFtp();
...