test(react-grab): unit-test Next runtime detection + base path

packages/react-grab/tests/get-next-base-path.test.ts

@@ -0,0 +1,55 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vite-plus/test";
+
+const globalWithDocument = globalThis as { document?: unknown };
+let originalDocument: unknown;
+
+const stubScriptSource = (source: string | null): void => {
+  globalWithDocument.document = {
+    querySelector: () => (source === null ? null : { src: source }),
+  };
+};
+
+// getNextBasePath memoizes at module scope with no reset hook, so each branch
+// needs a freshly imported module to act as its "first call".
+const loadGetNextBasePath = async (): Promise<() => string> => {
+  vi.resetModules();
+  return (await import("../src/utils/get-next-base-path.js")).getNextBasePath;
+};
+
+beforeEach(() => {
+  originalDocument = globalWithDocument.document;
+});
+
+afterEach(() => {
+  globalWithDocument.document = originalDocument;
+  vi.resetModules();
+});
+
+describe("getNextBasePath", () => {
+  it("returns the prefix before /_next/ when a basePath is configured", async () => {
+    stubScriptSource("http://localhost:3000/app/_next/static/chunks/main.js");
+    const getNextBasePath = await loadGetNextBasePath();
+    expect(getNextBasePath()).toBe("/app");
+  });
+
+  it("returns an empty string when scripts load from the root /_next/", async () => {
+    stubScriptSource("http://localhost:3000/_next/static/chunks/main.js");
+    const getNextBasePath = await loadGetNextBasePath();
+    expect(getNextBasePath()).toBe("");
+  });
+
+  it("returns an empty string when no /_next/ script is present", async () => {
+    stubScriptSource(null);
+    const getNextBasePath = await loadGetNextBasePath();
+    expect(getNextBasePath()).toBe("");
+  });
+
+  it("memoizes the first computed base path", async () => {
+    stubScriptSource("http://localhost:3000/app/_next/static/chunks/main.js");
+    const getNextBasePath = await loadGetNextBasePath();
+    expect(getNextBasePath()).toBe("/app");
+
+    stubScriptSource("http://localhost:3000/other/_next/static/chunks/main.js");
+    expect(getNextBasePath()).toBe("/app");
+  });
+});

packages/react-grab/tests/is-next-project-runtime.test.ts

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+import { afterEach, beforeEach, describe, expect, it } from "vite-plus/test";
+import { isNextProjectRuntime } from "../src/utils/is-next-project-runtime.js";
+
+interface DocumentStub {
+  getElementById: (id: string) => unknown;
+  querySelector: (selector: string) => unknown;
+}
+
+const globalWithDocument = globalThis as { document?: unknown };
+let originalDocument: unknown;
+
+const stubDocument = (stub: DocumentStub | undefined): void => {
+  globalWithDocument.document = stub;
+};
+
+beforeEach(() => {
+  originalDocument = globalWithDocument.document;
+});
+
+afterEach(() => {
+  globalWithDocument.document = originalDocument;
+});
+
+describe("isNextProjectRuntime", () => {
+  it("is false when there is no document (e.g. server runtime)", () => {
+    stubDocument(undefined);
+    expect(isNextProjectRuntime(true)).toBe(false);
+  });
+
+  it("detects the __NEXT_DATA__ script (Pages Router)", () => {
+    stubDocument({
+      getElementById: (id) => (id === "__NEXT_DATA__" ? {} : null),
+      querySelector: () => null,
+    });
+    expect(isNextProjectRuntime(true)).toBe(true);
+  });
+
+  it("detects the nextjs-portal element (App Router dev overlay)", () => {
+    stubDocument({
+      getElementById: () => null,
+      querySelector: (selector) => (selector === "nextjs-portal" ? {} : null),
+    });
+    expect(isNextProjectRuntime(true)).toBe(true);
+  });
+
+  it("is false when neither Next marker is present", () => {
+    stubDocument({ getElementById: () => null, querySelector: () => null });
+    expect(isNextProjectRuntime(true)).toBe(false);
+  });
+
+  it("memoizes the result until revalidation is requested", () => {
+    stubDocument({
+      getElementById: (id) => (id === "__NEXT_DATA__" ? {} : null),
+      querySelector: () => null,
+    });
+    expect(isNextProjectRuntime(true)).toBe(true);
+
+    // The cached value holds even though the markers are now gone...
+    stubDocument({ getElementById: () => null, querySelector: () => null });
+    expect(isNextProjectRuntime()).toBe(true);
+
+    // ...until a revalidate pass re-reads the DOM.
+    expect(isNextProjectRuntime(true)).toBe(false);
+  });
+});