test: add widget shared component coverage

src/components/widgets/widget/container_form.test.jsx

@@ -0,0 +1,23 @@
+// @vitest-environment jsdom
+
+import { fireEvent, render } from "@testing-library/react";
+import { describe, expect, it, vi } from "vitest";
+
+import ContainerForm from "./container_form";
+
+describe("components/widgets/widget/container_form", () => {
+  it("calls callback on submit", () => {
+    const cb = vi.fn((e) => e.preventDefault());
+
+    const { container } = render(
+      <ContainerForm options={{}} callback={cb}>
+        {[<div key="c">child</div>]}
+      </ContainerForm>,
+    );
+
+    const form = container.querySelector("form");
+    fireEvent.submit(form);
+
+    expect(cb).toHaveBeenCalledTimes(1);
+  });
+});