Update and refine alert modals

tests/components/Alert.test.tsx

@@ -1,6 +1,10 @@
 import React from "react";
+import { describe, expect, it, vi } from "vitest";
+import { screen } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
 import Alert from "../../app/components/modals/Alert";
 import { componentTestSuite } from "../utils/componentTestSuite";
+import { renderWithProviders as render } from "../utils/test-utils";
 
 type AlertProps = React.ComponentProps<typeof Alert>;
 
@@ -16,6 +20,7 @@ componentTestSuite<AlertProps>({
     description: "Optional description",
     status: "positive",
     type: "banner",
+    size: "m",
   },
   primaryRole: "alert",
   testCases: {
@@ -26,3 +31,30 @@ componentTestSuite<AlertProps>({
     errorState: false,
   },
 });
+
+describe("Alert dismiss control", () => {
+  it("omits close button when onClose is absent", () => {
+    render(<Alert title="T" description="D" />);
+    expect(
+      screen.queryByRole("button", { name: "Close alert" }),
+    ).not.toBeInTheDocument();
+  });
+
+  it("renders close when onClose is provided", async () => {
+    const user = userEvent.setup();
+    const onClose = vi.fn();
+    render(<Alert title="T" onClose={onClose} />);
+    await user.click(screen.getByRole("button", { name: "Close alert" }));
+    expect(onClose).toHaveBeenCalledTimes(1);
+  });
+
+  it("omits close when hasTrailingIcon is false even if onClose exists", () => {
+    const onClose = vi.fn();
+    render(
+      <Alert title="T" onClose={onClose} hasTrailingIcon={false} />,
+    );
+    expect(
+      screen.queryByRole("button", { name: "Close alert" }),
+    ).not.toBeInTheDocument();
+  });
+});