Base: Add man page for test-js(1)

Author: https://github.com/linusg
Commit: https://github.com/SerenityOS/serenity/commit/4c845b35ac7
Pull-request: https://github.com/SerenityOS/serenity/pull/2720
Reviewed-by: https://github.com/bugaevc ✅

Base/usr/share/man/man1/js.md

@@ -46,3 +46,7 @@ undefined
 77
 undefined
 ```
+
+## See also
+
+* [`test-js`(1)](test-js.md)

Base/usr/share/man/man1/test-js.md

@@ -0,0 +1,37 @@
+## Name
+
+test-js - run the LibJS test suite
+
+## Synopsis
+
+```**sh
+$ test-js [options...]
+```
+
+## Description
+
+`test-js` runs the LibJS test suite located in `/home/anon/js-tests`. These
+tests are using a custom JavaScript testing framework inspired by
+[Jest](https://jestjs.io) (see `test-common.js` in the same directory).
+
+## Options
+
+* `-t`, `--show-time`: Show duration of each test
+
+## Examples
+
+A very simple test looks like this:
+
+```js
+describe("Examples from Gary Bernhardt's 'Wat' talk", () => {
+    test("Na na na na na na na na na na na na na na na na Batman!", () => {
+        expect(Array(16).join("wat" - 1) + " Batman!").toBe(
+            "NaNNaNNaNNaNNaNNaNNaNNaNNaNNaNNaNNaNNaNNaNNaN Batman!"
+        );
+    });
+});
+```
+
+## See also
+
+* [`js`(1)](js.md)