adding monkeytype

frontend/__tests__/vitest.d.ts

@@ -0,0 +1,24 @@
+import type { Assertion, AsymmetricMatchersContaining } from "vitest";
+import { TestActivityDay } from "../src/ts/elements/test-activity-calendar";
+
+interface ActivityDayMatchers<R = TestActivityDay> {
+  toBeDate: (date: string) => ActivityDayMatchers<R>;
+  toHaveTests: (tests: number) => ActivityDayMatchers<R>;
+  toHaveLevel: (level?: string | number) => ActivityDayMatchers<R>;
+  toBeFiller: () => ActivityDayMatchers<R>;
+}
+
+/// <reference types="vitest" />
+import "@testing-library/jest-dom";
+
+declare module "vitest" {
+  interface Assertion<T = any> extends ActivityDayMatchers<T> {}
+  interface AsymmetricMatchersContaining extends ActivityDayMatchers {}
+}
+
+interface MatcherResult {
+  pass: boolean;
+  message: () => string;
+  actual?: unknown;
+  expected?: unknown;
+}