test(coverage): bootstrap vitest unit infra and add tests at 90%+ per file (#1245) (#1269)

* test(coverage): bootstrap vitest unit infra and add tests at 90%+ per file (#1245)

Establishes the unit-test runtime AGENTS.md mandates: a vitest "unit"
project alongside the existing storybook project, RTL + jest-dom +
happy-dom, a Mantine-aware render helper, and a 90%-line per-file
coverage gate enforced by CI. Adds 66 test files covering all 62
components under elements/groups/screens/views, plus core/mcp and
clients/web/src/utils. Total: 577 tests, 98.7% line coverage globally.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* test(coverage): address PR #1269 review feedback

- AGENTS.md: correct coverage gate description (lines ≥ 90, statements ≥ 85,
  functions ≥ 80, branches ≥ 50) with rationale for the relaxed branch
  threshold
- InspectorView.test.tsx: document what the Math.random() mock values
  (0.1 / 0.99) control vs. STUB_SUCCESS_RATE in InspectorView.tsx
- vite.config.ts / tsconfig.test.json: drop unused `globals: true` and the
  `vitest/globals` type now that every test file imports describe/it/expect/vi
  explicitly; manual `afterEach(cleanup)` in setup.ts remains required because
  testing-library auto-cleanup relies on globalThis.afterEach

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

clients/web/src/components/screens/ResourcesScreen/ResourcesScreen.test.tsx

@@ -0,0 +1,167 @@
+import { describe, it, expect, vi } from "vitest";
+import userEvent from "@testing-library/user-event";
+import type {
+  Resource,
+  ResourceTemplate,
+  ReadResourceResult,
+} from "@modelcontextprotocol/sdk/types.js";
+import { renderWithMantine, screen } from "../../../test/renderWithMantine";
+import { ResourcesScreen } from "./ResourcesScreen";
+
+const resources: Resource[] = [
+  { uri: "file:///x", name: "x.txt" },
+  { uri: "file:///y", name: "y.txt" },
+];
+
+const templates: ResourceTemplate[] = [
+  { uriTemplate: "file:///{path}", name: "files" },
+];
+
+const baseProps = {
+  resources,
+  templates,
+  subscriptions: [],
+  listChanged: false,
+  onRefreshList: vi.fn(),
+  onReadResource: vi.fn(),
+  onSubscribeResource: vi.fn(),
+  onUnsubscribeResource: vi.fn(),
+};
+
+const okResult: ReadResourceResult = {
+  contents: [{ uri: "file:///x", text: "embedded contents" }],
+};
+
+describe("ResourcesScreen", () => {
+  it("renders empty preview state when nothing is selected", () => {
+    renderWithMantine(<ResourcesScreen {...baseProps} />);
+    expect(
+      screen.getByText("Select a resource to preview"),
+    ).toBeInTheDocument();
+  });
+
+  it("shows the read error alert when error and a resource is selected", async () => {
+    const user = userEvent.setup();
+    renderWithMantine(
+      <ResourcesScreen
+        {...baseProps}
+        readState={{ status: "error", error: "boom" }}
+      />,
+    );
+    await user.click(screen.getByText("x.txt"));
+    expect(screen.getByText("Read Error")).toBeInTheDocument();
+    expect(screen.getByText("boom")).toBeInTheDocument();
+  });
+
+  it("falls back to default error when error message is missing", async () => {
+    const user = userEvent.setup();
+    renderWithMantine(
+      <ResourcesScreen {...baseProps} readState={{ status: "error" }} />,
+    );
+    await user.click(screen.getByText("x.txt"));
+    expect(screen.getByText("Failed to read resource")).toBeInTheDocument();
+  });
+
+  it("shows the loading state when reading", async () => {
+    const user = userEvent.setup();
+    renderWithMantine(
+      <ResourcesScreen {...baseProps} readState={{ status: "pending" }} />,
+    );
+    await user.click(screen.getByText("x.txt"));
+    expect(screen.getByText("Reading resource...")).toBeInTheDocument();
+  });
+
+  it("renders the preview panel when readState has a result", async () => {
+    const user = userEvent.setup();
+    renderWithMantine(
+      <ResourcesScreen
+        {...baseProps}
+        readState={{
+          status: "ok",
+          uri: "file:///x",
+          result: okResult,
+        }}
+      />,
+    );
+    await user.click(screen.getByText("x.txt"));
+    expect(screen.getByText("embedded contents")).toBeInTheDocument();
+  });
+
+  it("synthesizes a Resource for template-expanded URIs not in the list", () => {
+    renderWithMantine(
+      <ResourcesScreen
+        {...baseProps}
+        resources={[]}
+        readState={{
+          status: "ok",
+          uri: "file:///synthetic",
+          result: { contents: [{ uri: "file:///synthetic", text: "syn" }] },
+        }}
+      />,
+    );
+    expect(
+      screen.getByText("Select a resource to preview"),
+    ).toBeInTheDocument();
+  });
+
+  it("renders the template panel when a template is selected", async () => {
+    const user = userEvent.setup();
+    renderWithMantine(<ResourcesScreen {...baseProps} />);
+    await user.click(screen.getByText("Templates (1)"));
+    await user.click(screen.getByText("files"));
+    expect(
+      screen.getByText("Enter a URI and click Read to preview"),
+    ).toBeInTheDocument();
+  });
+
+  it("renders empty state when a resource is selected but no readState", async () => {
+    const user = userEvent.setup();
+    renderWithMantine(<ResourcesScreen {...baseProps} />);
+    await user.click(screen.getByText("x.txt"));
+    expect(screen.getByText("Click to read this resource")).toBeInTheDocument();
+  });
+
+  it("forwards refresh and subscribe events from the preview panel", async () => {
+    const user = userEvent.setup();
+    const onReadResource = vi.fn();
+    const onSubscribeResource = vi.fn();
+    renderWithMantine(
+      <ResourcesScreen
+        {...baseProps}
+        onReadResource={onReadResource}
+        onSubscribeResource={onSubscribeResource}
+        readState={{
+          status: "ok",
+          uri: "file:///x",
+          result: okResult,
+          isSubscribed: false,
+        }}
+      />,
+    );
+    await user.click(screen.getByText("x.txt"));
+    await user.click(screen.getByRole("button", { name: "Refresh" }));
+    expect(onReadResource).toHaveBeenCalledWith("file:///x");
+    await user.click(screen.getByRole("button", { name: "Subscribe" }));
+    expect(onSubscribeResource).toHaveBeenCalledWith("file:///x");
+  });
+
+  it("invokes onUnsubscribeResource when already subscribed", async () => {
+    const user = userEvent.setup();
+    const onUnsubscribeResource = vi.fn();
+    renderWithMantine(
+      <ResourcesScreen
+        {...baseProps}
+        onUnsubscribeResource={onUnsubscribeResource}
+        readState={{
+          status: "ok",
+          uri: "file:///x",
+          result: okResult,
+          isSubscribed: true,
+        }}
+      />,
+    );
+    await user.click(screen.getByText("x.txt"));
+    await user.click(screen.getByRole("button", { name: "Unsubscribe" }));
+    expect(onUnsubscribeResource).toHaveBeenCalledWith("file:///x");
+  });
+});