test: expand mime detection coverage

src/media/mime.test.ts

@@ -0,0 +1,57 @@
+import JSZip from "jszip";
+import { describe, expect, it } from "vitest";
+
+import { detectMime } from "./mime.js";
+
+async function makeOoxmlZip(opts: {
+  mainMime: string;
+  partPath: string;
+}): Promise<Buffer> {
+  const zip = new JSZip();
+  zip.file(
+    "[Content_Types].xml",
+    `<Types><Override PartName="${opts.partPath}" ContentType="${opts.mainMime}.main+xml"/></Types>`,
+  );
+  zip.file(opts.partPath.slice(1), "<xml/>");
+  return await zip.generateAsync({ type: "nodebuffer" });
+}
+
+describe("mime detection", () => {
+  it("detects docx from buffer", async () => {
+    const buf = await makeOoxmlZip({
+      mainMime:
+        "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+      partPath: "/word/document.xml",
+    });
+    const mime = await detectMime({ buffer: buf, filePath: "/tmp/file.bin" });
+    expect(mime).toBe(
+      "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+    );
+  });
+
+  it("detects pptx from buffer", async () => {
+    const buf = await makeOoxmlZip({
+      mainMime:
+        "application/vnd.openxmlformats-officedocument.presentationml.presentation",
+      partPath: "/ppt/presentation.xml",
+    });
+    const mime = await detectMime({ buffer: buf, filePath: "/tmp/file.bin" });
+    expect(mime).toBe(
+      "application/vnd.openxmlformats-officedocument.presentationml.presentation",
+    );
+  });
+
+  it("prefers extension mapping over generic zip", async () => {
+    const zip = new JSZip();
+    zip.file("hello.txt", "hi");
+    const buf = await zip.generateAsync({ type: "nodebuffer" });
+
+    const mime = await detectMime({
+      buffer: buf,
+      filePath: "/tmp/file.xlsx",
+    });
+    expect(mime).toBe(
+      "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
+    );
+  });
+});