feat: add CSSNumberish support with type-safe conversion helpers

global.d.ts

@@ -1,12 +1,41 @@
+/* eslint-disable @typescript-eslint/no-empty-interface */
+/* eslint-disable @typescript-eslint/no-unused-vars */
+import { Mock as ViMock } from 'vitest';
+
+// By re-declaring the vitest module, we can augment its types.
+declare module 'vitest' {
+  /**
+   * Augment vitest's Mock type to be compatible with jest.Mock.
+   * This allows us to use a single, consistent type for mocks across both test runners.
+   */
+  export interface Mock<A extends unknown[] = unknown[], R = unknown>
+    extends jest.Mock<A, R> {}
+
+  /**
+   * Augment vitest's SpyInstance to be compatible with jest.SpyInstance.
+   * Note the swapped generic arguments:
+   * - Vitest: SpyInstance<[Args], ReturnValue>
+   * - Jest: SpyInstance<ReturnValue, [Args]>
+   * This declaration makes them interoperable.
+   */
+  export interface SpyInstance<A extends unknown[] = unknown[], R = unknown>
+    extends jest.SpyInstance<R, A> {}
+}
+
 export {};
 
+interface Runner {
+  name: 'vi' | 'jest';
+  useFakeTimers: () => void;
+  useRealTimers: () => void;
+  advanceTimersByTime: (time: number) => Promise<void> | void;
+  /** A generic function to create a mock function, compatible with both runners. */
+  fn: () => jest.Mock<unknown[], unknown>;
+  /** A generic function to spy on a method, compatible with both runners. */
+  spyOn: typeof jest.spyOn;
+}
+
 declare global {
   // eslint-disable-next-line no-var
-  var runner: {
-    name: 'vi' | 'jest';
-    useFakeTimers: () => void;
-    useRealTimers: () => void;
-    advanceTimersByTime: (time: number) => Promise<void>;
-    fn: () => jest.Mock<any, any>;
-  };
+  var runner: Runner;
 }

jest-setup.ts

@@ -14,10 +14,15 @@ function fn() {
   return jest.fn();
 }
 
+function spyOn(...args: Parameters<typeof jest.spyOn>) {
+  return jest.spyOn(...args);
+}
+
 globalThis.runner = {
   name: 'jest',
   useFakeTimers,
   useRealTimers,
   advanceTimersByTime,
   fn,
+  spyOn,
 };

package.json

@@ -1,6 +1,6 @@
 {
   "name": "jsdom-testing-mocks",
-  "version": "1.13.1",
+  "version": "1.14.0",
   "author": "Ivan Galiatin",
   "license": "MIT",
   "description": "A set of tools for emulating browser behavior in jsdom environment",