feat: add keyboard navigation to combobox and select fields on web

packages/app/src/components/ui/combobox-keyboard.test.ts

@@ -0,0 +1,33 @@
+import { describe, expect, it } from "vitest";
+
+import { getNextActiveIndex } from "./combobox-keyboard";
+
+describe("getNextActiveIndex", () => {
+  it("returns -1 when itemCount is 0", () => {
+    expect(
+      getNextActiveIndex({ currentIndex: 0, itemCount: 0, key: "ArrowDown" })
+    ).toBe(-1);
+  });
+
+  it("starts at 0 on ArrowDown when no active item", () => {
+    expect(
+      getNextActiveIndex({ currentIndex: -1, itemCount: 3, key: "ArrowDown" })
+    ).toBe(0);
+  });
+
+  it("starts at last on ArrowUp when no active item", () => {
+    expect(
+      getNextActiveIndex({ currentIndex: -1, itemCount: 3, key: "ArrowUp" })
+    ).toBe(2);
+  });
+
+  it("wraps around on ArrowDown and ArrowUp", () => {
+    expect(
+      getNextActiveIndex({ currentIndex: 2, itemCount: 3, key: "ArrowDown" })
+    ).toBe(0);
+    expect(
+      getNextActiveIndex({ currentIndex: 0, itemCount: 3, key: "ArrowUp" })
+    ).toBe(2);
+  });
+});
+