Added first tests.

package.json

@@ -18,6 +18,7 @@
   "license": "MIT",
   "scripts": {
     "build": "pika build",
+    "test": "jest",
     "publish": "pika publish",
     "docz:dev": "docz dev",
     "docz:build": "docz build",
@@ -30,6 +31,13 @@
       "@babel/preset-react"
     ]
   },
+  "jest": {
+    "testPathIgnorePatterns": [
+      "pkg",
+      ".docz",
+      "docs"
+    ]
+  },
   "@pika/pack": {
     "pipeline": [
       [
@@ -60,13 +68,20 @@
     "@pika/plugin-build-types": "0.9.2",
     "@pika/plugin-build-web": "0.9.2",
     "@pika/plugin-ts-standard-pkg": "0.9.2",
+    "@testing-library/react": "^10.0.2",
+    "@testing-library/react-hooks": "3.2.1",
+    "@types/jest": "^25.2.1",
     "@types/react": "16.9.32",
     "@types/react-dom": "16.9.6",
+    "@types/testing-library__react": "^10.0.1",
+    "@types/testing-library__react-hooks": "^3.2.0",
     "docz": "2.3.0",
     "emotion-theming": "10.0.27",
     "gatsby-plugin-emotion": "4.2.1",
+    "jest": "25.2.7",
     "react": "16.13.1",
     "react-dom": "16.13.1",
+    "react-test-renderer": "16.13.1",
     "typescript": "3.8.3"
   },
   "peerDependencies": {

src/index.test.tsx

@@ -0,0 +1,41 @@
+import React, {useState} from "react";
+import {useHotkeys} from "./index";
+import {act, renderHook} from "@testing-library/react-hooks";
+import { fireEvent } from "@testing-library/react";
+
+export default function useWrapper(keys: string) {
+  const [count, setCount] = useState(0);
+  const increment = () => setCount((x) => x + 1);
+
+  useHotkeys(keys, increment);
+
+  return count;
+}
+
+test('useHotkeys should listen to key presses', () => {
+    const { result } = renderHook(() => useWrapper('a'));
+
+    expect(result.current).toBe(0);
+
+    act(() => {
+      fireEvent.keyDown(document.body, { key: 'a', keyCode: 65 });
+
+      return undefined;
+    });
+
+    expect(result.current).toBe(1);
+});
+
+test('useHotkeys should listen to its own context', function () {
+  const resultA = renderHook(() => useWrapper('a'));
+  const resultB = renderHook(() => useWrapper('b'));
+
+  act(() => {
+    fireEvent.keyDown(document.body, { key: 'a', keyCode: 65 });
+
+    return undefined;
+  });
+
+  expect(resultA.result.current).toBe(1);
+  expect(resultB.result.current).toBe(0);
+});