Add tests for HistoryAndNotifications component

Tests cover basic rendering, numbering, expansion functionality, and
expansion state persistence when new items are added. Includes
regression test for notification expansion state tracking bug.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

client/src/components/__tests__/History.test.tsx

@@ -0,0 +1,216 @@
+import { render, screen, fireEvent } from "@testing-library/react";
+import "@testing-library/jest-dom";
+import { describe, it, expect, jest } from "@jest/globals";
+import HistoryAndNotifications from "../History";
+import { ServerNotification } from "@modelcontextprotocol/sdk/types.js";
+
+// Mock JsonView component
+jest.mock("../JsonView", () => {
+  return function JsonView({ data }: { data: string }) {
+    return <div data-testid="json-view">{data}</div>;
+  };
+});
+
+describe("HistoryAndNotifications", () => {
+  const mockRequestHistory = [
+    {
+      request: JSON.stringify({ method: "test/method1", params: {} }),
+      response: JSON.stringify({ result: "success" }),
+    },
+    {
+      request: JSON.stringify({ method: "test/method2", params: {} }),
+      response: JSON.stringify({ result: "success" }),
+    },
+  ];
+
+  const mockNotifications: ServerNotification[] = [
+    {
+      method: "notification/test1",
+      params: { message: "First notification" },
+    },
+    {
+      method: "notification/test2",
+      params: { message: "Second notification" },
+    },
+  ];
+
+  it("renders history and notifications sections", () => {
+    render(
+      <HistoryAndNotifications
+        requestHistory={mockRequestHistory}
+        serverNotifications={mockNotifications}
+      />,
+    );
+
+    expect(screen.getByText("History")).toBeInTheDocument();
+    expect(screen.getByText("Server Notifications")).toBeInTheDocument();
+  });
+
+  it("displays request history items with correct numbering", () => {
+    render(
+      <HistoryAndNotifications
+        requestHistory={mockRequestHistory}
+        serverNotifications={[]}
+      />,
+    );
+
+    // Items should be numbered in reverse order (newest first)
+    expect(screen.getByText("2. test/method2")).toBeInTheDocument();
+    expect(screen.getByText("1. test/method1")).toBeInTheDocument();
+  });
+
+  it("displays server notifications with correct numbering", () => {
+    render(
+      <HistoryAndNotifications
+        requestHistory={[]}
+        serverNotifications={mockNotifications}
+      />,
+    );
+
+    // Items should be numbered in reverse order (newest first)
+    expect(screen.getByText("2. notification/test2")).toBeInTheDocument();
+    expect(screen.getByText("1. notification/test1")).toBeInTheDocument();
+  });
+
+  it("expands and collapses request items when clicked", () => {
+    render(
+      <HistoryAndNotifications
+        requestHistory={mockRequestHistory}
+        serverNotifications={[]}
+      />,
+    );
+
+    const firstRequestHeader = screen.getByText("2. test/method2");
+
+    // Initially collapsed - should show ▶ arrows (there are multiple)
+    expect(screen.getAllByText("▶")).toHaveLength(2);
+    expect(screen.queryByText("Request:")).not.toBeInTheDocument();
+
+    // Click to expand
+    fireEvent.click(firstRequestHeader);
+
+    // Should now be expanded - one ▼ and one ▶
+    expect(screen.getByText("▼")).toBeInTheDocument();
+    expect(screen.getAllByText("▶")).toHaveLength(1);
+    expect(screen.getByText("Request:")).toBeInTheDocument();
+    expect(screen.getByText("Response:")).toBeInTheDocument();
+  });
+
+  it("expands and collapses notification items when clicked", () => {
+    render(
+      <HistoryAndNotifications
+        requestHistory={[]}
+        serverNotifications={mockNotifications}
+      />,
+    );
+
+    const firstNotificationHeader = screen.getByText("2. notification/test2");
+
+    // Initially collapsed
+    expect(screen.getAllByText("▶")).toHaveLength(2);
+    expect(screen.queryByText("Details:")).not.toBeInTheDocument();
+
+    // Click to expand
+    fireEvent.click(firstNotificationHeader);
+
+    // Should now be expanded
+    expect(screen.getByText("▼")).toBeInTheDocument();
+    expect(screen.getAllByText("▶")).toHaveLength(1);
+    expect(screen.getByText("Details:")).toBeInTheDocument();
+  });
+
+  it("maintains expanded state when new notifications are added", () => {
+    const { rerender } = render(
+      <HistoryAndNotifications
+        requestHistory={[]}
+        serverNotifications={mockNotifications}
+      />,
+    );
+
+    // Find and expand the older notification (should be "1. notification/test1")
+    const olderNotificationHeader = screen.getByText("1. notification/test1");
+    fireEvent.click(olderNotificationHeader);
+
+    // Verify it's expanded
+    expect(screen.getByText("Details:")).toBeInTheDocument();
+
+    // Add a new notification at the beginning (simulating real behavior)
+    const newNotifications: ServerNotification[] = [
+      {
+        method: "notification/new",
+        params: { message: "New notification" },
+      },
+      ...mockNotifications,
+    ];
+
+    // Re-render with new notifications
+    rerender(
+      <HistoryAndNotifications
+        requestHistory={[]}
+        serverNotifications={newNotifications}
+      />,
+    );
+
+    // The original notification should still be expanded
+    // It's now numbered as "2. notification/test1" due to the new item
+    expect(screen.getByText("3. notification/test2")).toBeInTheDocument();
+    expect(screen.getByText("2. notification/test1")).toBeInTheDocument();
+    expect(screen.getByText("1. notification/new")).toBeInTheDocument();
+
+    // The originally expanded notification should still show its details
+    expect(screen.getByText("Details:")).toBeInTheDocument();
+  });
+
+  it("maintains expanded state when new requests are added", () => {
+    const { rerender } = render(
+      <HistoryAndNotifications
+        requestHistory={mockRequestHistory}
+        serverNotifications={[]}
+      />,
+    );
+
+    // Find and expand the older request (should be "1. test/method1")
+    const olderRequestHeader = screen.getByText("1. test/method1");
+    fireEvent.click(olderRequestHeader);
+
+    // Verify it's expanded
+    expect(screen.getByText("Request:")).toBeInTheDocument();
+    expect(screen.getByText("Response:")).toBeInTheDocument();
+
+    // Add a new request at the beginning
+    const newRequestHistory = [
+      {
+        request: JSON.stringify({ method: "test/new_method", params: {} }),
+        response: JSON.stringify({ result: "new success" }),
+      },
+      ...mockRequestHistory,
+    ];
+
+    // Re-render with new request history
+    rerender(
+      <HistoryAndNotifications
+        requestHistory={newRequestHistory}
+        serverNotifications={[]}
+      />,
+    );
+
+    // The original request should still be expanded
+    // It's now numbered as "2. test/method1" due to the new item
+    expect(screen.getByText("3. test/method2")).toBeInTheDocument();
+    expect(screen.getByText("2. test/method1")).toBeInTheDocument();
+    expect(screen.getByText("1. test/new_method")).toBeInTheDocument();
+
+    // The originally expanded request should still show its details
+    expect(screen.getByText("Request:")).toBeInTheDocument();
+    expect(screen.getByText("Response:")).toBeInTheDocument();
+  });
+
+  it("displays empty state messages when no data is available", () => {
+    render(
+      <HistoryAndNotifications requestHistory={[]} serverNotifications={[]} />,
+    );
+
+    expect(screen.getByText("No history yet")).toBeInTheDocument();
+    expect(screen.getByText("No notifications yet")).toBeInTheDocument();
+  });
+});