fix: show disk usage for the mount being browsed (#1347)

plugins/file-manager/tests/frontend/disk-info.test.ts

@@ -0,0 +1,35 @@
+import { describe, expect, it } from "vitest";
+import {
+  mountForPath,
+  type DiskFilesystem,
+} from "../../src/frontend/disk-info";
+
+function fs(mount: string): DiskFilesystem {
+  return {
+    filesystem: mount,
+    type: "ext4",
+    mount,
+    percent: 10,
+    usedHuman: "1G",
+    totalHuman: "10G",
+    availableHuman: "9G",
+    usedBytes: 1,
+    totalBytes: 10,
+    availableBytes: 9,
+  };
+}
+
+describe("mountForPath", () => {
+  const list = [fs("/"), fs("/volume1"), fs("/volume10")];
+
+  it("picks the deepest mount that holds the path", () => {
+    expect(mountForPath(list, "/volume1/share")?.mount).toBe("/volume1");
+    expect(mountForPath(list, "/volume10")?.mount).toBe("/volume10");
+    expect(mountForPath(list, "/etc")?.mount).toBe("/");
+  });
+
+  it("returns null without a path or mounts", () => {
+    expect(mountForPath(list, null)).toBeNull();
+    expect(mountForPath([], "/etc")).toBeNull();
+  });
+});