Add tests for ButtonLink component

This commit introduces tests for the ButtonLink component to validate three main functionalities: display of children as text, the rendering of a link, and ensuring the link points to the correct target.

frontend/src/components/ButtonLink/ButtonLink.component.test.tsx

@@ -0,0 +1,34 @@
+import { render, screen } from "@testing-library/react";
+import "@testing-library/jest-dom";
+import ButtonLink from "./ButtonLink.tsx";
+import { MemoryRouter } from "react-router-dom";
+
+test("ButtonLink component displays children as text", () => {
+  render(
+    <MemoryRouter>
+      <ButtonLink href="/my-url">Click here</ButtonLink>
+    </MemoryRouter>
+  );
+  const text = screen.getByText(/click here/i);
+  expect(text).toBeInTheDocument();
+});
+
+test("ButtonLink component displays a link", () => {
+  render(
+    <MemoryRouter>
+      <ButtonLink href="/my-url">Click here</ButtonLink>
+    </MemoryRouter>
+  );
+  const button = screen.getByRole("link");
+  expect(button).toBeInTheDocument();
+});
+
+test("ButtonLink component links to the correct target", () => {
+  render(
+    <MemoryRouter>
+      <ButtonLink href="/my-url">Click here</ButtonLink>
+    </MemoryRouter>
+  );
+  const button = screen.getByRole("link");
+  expect(button).toHaveAttribute("href", "/my-url");
+});