Add unit test

Author: nojaf

tests/DOMAPI/AddEventListener__test.js

@@ -0,0 +1,21 @@
+open WebAPI
+open WebAPI.Global
+
+let button = document->Document.querySelector("button")->Null.toOption
+let h2 = document->Document.querySelector("h2")->Null.toOption
+
+switch (button, h2) {
+| (Some(button), Some(h2)) =>
+  button->Element.addEventListener(EventAPI.Click, (e: UIEventsAPI.mouseEvent) => {
+    Console.log(`Button clicked, ${Int.toString(e.button)}`)
+    switch h2.textContent {
+    | Null => h2.textContent = Value("1")
+    | Value(text) =>
+      switch Int.fromString(text) {
+      | None => h2.textContent = Value("1")
+      | Some(number) => h2.textContent = Value(Int.toString(number + 1))
+      }
+    }
+  })
+| _ => Console.log("Stuff not found")
+}