Add jest test for ref

test/Ref__test.re

@@ -0,0 +1,29 @@
+open Jest;
+open Expect;
+
+module Button_with_ref = {
+  [@react.component]
+  let make = (~children, ~ref) => {
+    <button ref role="FancyButton"> children </button>;
+  };
+};
+
+let getByRole = (role, container) => {
+  ReactTestingLibrary.getByRole(~matcher=`Str(role), container);
+};
+
+[@mel.get] external innerHTML: Dom.element => string = "innerHTML";
+
+describe("ref", () => {
+  test("can be passed as prop to a component", () => {
+    let domRef = React.createRef();
+    let container =
+      ReactTestingLibrary.render(
+        <Button_with_ref ref={ReactDOM.Ref.domRef(domRef)}>
+          {React.string("Click me")}
+        </Button_with_ref>,
+      );
+    let button = getByRole("FancyButton", container);
+    expect(button->innerHTML)->toBe("Click me");
+  })
+});