Update README.md: Deno tests

README.md

@@ -41,16 +41,17 @@ In both cases you will end up with a very basic webserver running locally on por
 
 ### Running the test suite
 
-Tests are written in [Jest](https://jestjs.io/). You can run them using this command in the project directory:
+Tests are written in [Deno](https://docs.deno.com/runtime/manual/basics/testing/). You can run them using this command in the project directory:
 
 ```bash
-npx jest ./__tests__/
+deno test --allow-read --importmap=./__tests__/importmap.json
 ```
 
-If you don't have NodeJS on your machine, you can run them by using Docker (also in the project directory):
+If you don't have Deno on your machine, you can run them by using Docker (also in the project directory):
 
 ```bash
-docker run -ti --rm --volume "${PWD}:/code" node:17.0 /bin/bash -c 'cd /code && npx jest ./__tests__/'
+docker run -ti --rm --volume "${PWD}:/code" denoland/deno:1.37.0 \
+    /bin/bash -c 'cd /code && deno test --allow-read --importmap=./__tests__/importmap.json'
 ```
 
 ## Related developments