How to run dotnet tests with automatic smart retry

When running dotnet test, there is no built-in mechanism to retry failed tests, and constructing the filter format for re-running them is non-trivial. This post showcases a new dotnet global tool dotnet-retest that fixes this.

TL;DR;:

Install:

dotnet tool install -g dotnet-retest

Run:

dotnet retest

Sometimes, flaky tests are just unavoidable for reasons that are outside the scope of this post. If you think those should never happen and never DO happen to you, this post is not for you :).

I have tried in the past to work around this by doing fancy bash scripting for CI retries but that approach had several limitations, not least that it required non-trivial work to incorporate across repos and workflows, and worst of all, that it doesn’t integrate easily with my usual flow of dotnet build / test.

In addition, I faced some challenges updating the script for some changes in how MacOS installs GNU grep and that was enough. Best to rething the solution from scratch.

And the result is a new global tool that runs dotnet test as a subprocess, similar to how dotnet watch works:

dotnet retest [options] -- [dotnet test options]

The -- separates the options for the retest tool itself (number of retries, reporting options, etc.) from the ones for dotnet test, which obviously can receive all the arguments you are currently passing in.

The smart progress reporting reduces console clutter by reusing the same line during the tests run, so you can get a glimpse at what’s going on, without scrolling the view.

retest