Skip to main content

.NET 8–It’s time to get rid of these flaky tests!

There is only one thing worse than having no tests and that is having flaky tests. You know, tests that sometimes fail and sometimes succeed when the code itself didn't change. One of the biggest reasons this can happen is when your tests have time related logic.

My tests succeed on Monday but not during the weekend.

Sidenote: there is a cool Azure DevOps feature specifically to handle and fix flaky tests. Anyway that is not the topic of this post.

In .NET 8 Microsoft tried to fix this by introducing a new time abstraction API. Instead of directly calling DateTime.Now or DateTime.UtcNow inside your code, you can now use the TimeProvider class and ITimer interface. Together they offer time abstraction functionality, facilitating the simulation of time in testing scenarios.

Remark: Microsoft was so nice to backport these APIs and made them available in a separate NuGet package Microsoft.Bcl.TimeProvider.

So now we can update our code to use the TimeProvider class instead:

If we now want to test our code we can use the Microsoft.Extensions.TimeProvider.Testing package. This includes a TimeProvider implementation called FakeTimeProvider which gives us explicit control over the flow of time.

An example:

These new abstractions can also be used in asynchronous program execution thanks to some new overloads:

Nice!

Labels:

Popular posts from this blog

.NET 8–Keyed/Named Services

A feature that a lot of IoC container libraries support but that was missing in the default DI container provided by Microsoft is the support for Keyed or Named Services. This feature allows you to register the same type multiple times using different names, allowing you to resolve a specific instance based on the circumstances. Although there is some controversy if supporting this feature is a good idea or not, it certainly can be handy. To support this feature a new interface IKeyedServiceProvider got introduced in .NET 8 providing 2 new methods on our ServiceProvider instance: object? GetKeyedService(Type serviceType, object? serviceKey); object GetRequiredKeyedService(Type serviceType, object? serviceKey); To use it, we need to register our service using one of the new extension methods: Resolving the service can be done either through the FromKeyedServices attribute: or by injecting the IKeyedServiceProvider interface and calling the GetRequiredKeyedServic...
Read more

Azure DevOps/ GitHub emoji

I’m really bad at remembering emoji’s. So here is cheat sheet with all emoji’s that can be used in tools that support the github emoji markdown markup: All credits go to rcaviers who created this list.
Read more

Kubernetes–Limit your environmental impact

Reducing the carbon footprint and CO2 emission of our (cloud) workloads, is a responsibility of all of us. If you are running a Kubernetes cluster, have a look at Kube-Green . kube-green is a simple Kubernetes operator that automatically shuts down (some of) your pods when you don't need them. A single pod produces about 11 Kg CO2eq per year( here the calculation). Reason enough to give it a try! Installing kube-green in your cluster The easiest way to install the operator in your cluster is through kubectl. We first need to install a cert-manager: kubectl apply -f https://github.com/cert-manager/cert-manager/releases/download/v1.14.5/cert-manager.yaml Remark: Wait a minute before you continue as it can take some time before the cert-manager is up & running inside your cluster. Now we can install the kube-green operator: kubectl apply -f https://github.com/kube-green/kube-green/releases/latest/download/kube-green.yaml Now in the namespace where we want t...
Read more