feat(jest): mithril component testing (#3679)

* feat(jest): create jest config package for unit testing
* chore: housekeeping
* fix: now we need to explicitly allow importing without extension
* fix: recover EditorDriverInterface import
* feat(jest): mithril component testing
* fix: use separate `tsconfig.test.json`

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

js-packages/jest-config/test-matchers.ts

@@ -0,0 +1,21 @@
+import { expect } from '@jest/globals';
+
+// Extend Jest with mithril component test matchers.
+expect.extend({
+  toHaveElement: intoMatcher((out: any, expected: any) => out.should.have(expected), 'Expected $received to have node $expected'),
+  toContainRaw: intoMatcher((out: any, expected: any) => out.should.contain(expected), 'Expected $received to contain $expected'),
+});
+
+function intoMatcher(callback: Function, message: string) {
+  return function (this: any, received: any, ...expected: any) {
+    try {
+      callback(received, ...expected);
+      return { pass: true, message: () => '' };
+    } catch (e) {
+      return {
+        pass: false,
+        message: () => message.replace('$expected', this.utils.printExpected(expected)).replace('$received', this.utils.printReceived('component')),
+      };
+    }
+  };
+}