✨ Fixes tests and linter for commons

docs/06-Testing-Guide.md

@@ -0,0 +1,39 @@
+# Testing guide #
+
+## Backend / Common
+
+You can run the tests directly with:
+
+```bash
+~/penpot/backend$ clojure -M:dev:tests
+```
+
+Alternatively, you can run them from a REPL. First starting a REPL.
+
+```bash
+~/penpot/backend$ scripts/repl
+```
+
+And then:
+
+```bash
+user=> (run-tests)
+user=> (run-tests 'namespace)
+user=> (run-tests 'namespace/test)
+```
+
+## Frontend
+
+Frontend tests have to be compiled first, and then run with node.
+
+```bash
+npx shadow-cljs compile tests && node target/tests.js
+```
+
+## Linter
+
+We can execute the linter for the whole codebase with the following command
+
+```bash
+npx clj-kondo --lint common:backend/src:frontend/src
+```