add utility function to augment tests with runtime config

src/testing.ts

@@ -0,0 +1,21 @@
+import { beforeAll as myBeforeAll } from "vitest";
+
+/**
+ * Testing utility to set the `window.config` object before tests are executed and clear it automatically afterwards
+ *
+ * @param beforeAll The beforeAll hook imported from vitest.
+ *  For some reason this needs to be passed as an argument and cannot be imported by this utility function on its own :/
+ * @param config The configuration that should be set on `window.config`
+ */
+export function withConfig(beforeAll: typeof myBeforeAll, config: Record<string, string>): void {
+    let previousValue: typeof window.config;
+
+    beforeAll(() => {
+        previousValue = window.config;
+        window.config = Object.freeze(config);
+
+        return () => {
+            window.config = previousValue;
+        };
+    });
+}