test: cover DocPage routeMap miss and LanguageSwitcher navigation error arm

src/__tests__/LanguageSwitcher.behavior.test.tsx

@@ -124,6 +124,33 @@ describe("LanguageSwitcher dropdown variant", () => {
     expect(screen.queryByRole("listbox")).toBeNull();
   });
 
+  it("logs and recovers when navigation throws, leaving the menu open", async () => {
+    const boom = new Error("router exploded");
+    replaceMock.mockImplementation(() => {
+      throw boom;
+    });
+    const errorSpy = vi.spyOn(console, "error").mockImplementation(() => {});
+
+    try {
+      render(<LanguageSwitcher />);
+      fireEvent.click(trigger());
+      fireEvent.click(screen.getByText(localeNames.ja));
+
+      await act(async () => {
+        await vi.advanceTimersByTimeAsync(200);
+      });
+
+      expect(replaceMock).toHaveBeenCalledTimes(1);
+      expect(errorSpy).toHaveBeenCalledWith("Failed to change language:", boom);
+      // The catch arm skips setIsOpen(false); finally still clears the spinner.
+      expect(screen.getByRole("listbox")).toBeTruthy();
+      expect(screen.queryByText("Switching...")).toBeNull();
+      expect(trigger().hasAttribute("disabled")).toBe(false);
+    } finally {
+      errorSpy.mockRestore();
+    }
+  });
+
   it("closes without navigating when the current locale is re-selected", () => {
     render(<LanguageSwitcher />);
     fireEvent.click(trigger());

src/__tests__/docs-slug-page.routemap-miss.test.tsx

@@ -0,0 +1,74 @@
+/**
+ * Covers the last arm of getPageContent in src/app/docs/[...slug]/page.tsx:
+ * the slug is a nav-generated route (present in buildPageMap's routeMap) but
+ * the mapped file exists in neither the project content directory nor the
+ * shared docs/content root. The lookup must fall through to `return null`,
+ * which DocPage turns into notFound(), rather than throwing or rendering an
+ * empty page.
+ *
+ * No committed nav entry points at a missing file (the sync step would fail
+ * the build), so the route is injected by wrapping buildPageMap.
+ */
+import { describe, expect, it, vi } from "vitest";
+
+const NOT_FOUND = new Error("NEXT_NOT_FOUND (test sentinel)");
+vi.mock("next/navigation", async importOriginal => {
+  const actual = await importOriginal<typeof import("next/navigation")>();
+  return {
+    ...actual,
+    usePathname: () => "/docs/hive/ghost-route",
+    notFound: () => {
+      throw NOT_FOUND;
+    },
+  };
+});
+
+const GHOST_ROUTE = "ghost-route";
+const GHOST_FILE = "ghost/not-on-disk.md";
+
+const { buildPageMapSpy } = vi.hoisted(() => ({ buildPageMapSpy: vi.fn() }));
+vi.mock("../app/docs/page-map", async importOriginal => {
+  const actual = await importOriginal<typeof import("../app/docs/page-map")>();
+  buildPageMapSpy.mockImplementation(
+    (projectId?: Parameters<typeof actual.buildPageMap>[0]) => {
+      const real = actual.buildPageMap(projectId);
+      return {
+        ...real,
+        routeMap: { ...real.routeMap, [GHOST_ROUTE]: GHOST_FILE },
+      };
+    }
+  );
+  return { ...actual, buildPageMap: buildPageMapSpy };
+});
+
+const { compileMdx } = vi.hoisted(() => ({
+  compileMdx: vi.fn(() => {
+    throw new Error(
+      "compileMdx must not be called when no source file resolves"
+    );
+  }),
+}));
+vi.mock("nextra/compile", () => ({ compileMdx }));
+
+import fs from "fs";
+import path from "path";
+import { docsContentPath, getContentPath } from "../app/docs/page-map";
+import DocPage from "../app/docs/[...slug]/page";
+
+describe("getPageContent — routeMap hit whose file is missing on disk", () => {
+  it("404s instead of rendering when the mapped file is absent from both content roots", async () => {
+    expect(fs.existsSync(path.join(getContentPath("hive"), GHOST_FILE))).toBe(
+      false
+    );
+    expect(fs.existsSync(path.join(docsContentPath, GHOST_FILE))).toBe(false);
+
+    await expect(
+      DocPage({ params: Promise.resolve({ slug: ["hive", GHOST_ROUTE] }) })
+    ).rejects.toBe(NOT_FOUND);
+
+    // The routeMap was consulted for this project and the miss never reached
+    // the MDX compiler.
+    expect(buildPageMapSpy).toHaveBeenCalledWith("hive");
+    expect(compileMdx).not.toHaveBeenCalled();
+  });
+});