From e165fa3a870db121f4f55ad85d34aed9b30185cf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Malinowski?= <p@malinowski.pm>
Date: Tue, 26 Nov 2024 17:18:16 +0100
Subject: [PATCH] test(multi-select): add test suite

---
 tests/MultiSelect/MultiSelect.test.ts | 124 ++++++++++++++++++++++++++
 tests/setup-tests.ts                  |   3 +
 2 files changed, 127 insertions(+)
 create mode 100644 tests/MultiSelect/MultiSelect.test.ts

diff --git a/tests/MultiSelect/MultiSelect.test.ts b/tests/MultiSelect/MultiSelect.test.ts
new file mode 100644
index 00000000..aed26b4a
--- /dev/null
+++ b/tests/MultiSelect/MultiSelect.test.ts
@@ -0,0 +1,124 @@
+import { render, screen } from "@testing-library/svelte";
+import { MultiSelect } from "carbon-components-svelte";
+import { user } from "../setup-tests";
+
+describe("MultiSelect sorts items correctly", () => {
+  /** Opens the dropdown. */
+  const openMenu = async () =>
+    await user.click(
+      await screen.findByLabelText("Open menu", {
+        selector: `[role="button"]`,
+      }),
+    );
+
+  /** Closes the dropdown. */
+  const closeMenu = async () =>
+    await user.click(
+      await screen.findByLabelText("Close menu", {
+        selector: `[role="button"]`,
+      }),
+    );
+
+  /** Toggles an option, identifying it by its `text` value. */
+  const toggleOption = async (optionText: string) =>
+    await user.click(
+      await screen.findByText((text) => text.trim() === optionText),
+    );
+
+  /** Fetches the `text` value of the nth option in the MultiSelect component. */
+  const nthRenderedOptionText = (index: number) =>
+    screen.queryAllByRole("option").at(index)?.textContent?.trim();
+
+  it("initially sorts items alphabetically", async () => {
+    render(MultiSelect, {
+      items: [
+        { id: "1", text: "C" },
+        { id: "3", text: "A" },
+        { id: "2", text: "B" },
+      ],
+    });
+
+    await openMenu();
+    expect(nthRenderedOptionText(0)).toBe("A");
+    expect(nthRenderedOptionText(1)).toBe("B");
+    expect(nthRenderedOptionText(2)).toBe("C");
+  });
+
+  it("immediately moves selected items to the top (with selectionFeedback: top)", async () => {
+    render(MultiSelect, {
+      items: [
+        { id: "3", text: "C" },
+        { id: "1", text: "A" },
+        { id: "2", text: "B" },
+      ],
+      selectionFeedback: "top",
+    });
+
+    await openMenu();
+    expect(nthRenderedOptionText(0)).toBe("A");
+
+    await toggleOption("C");
+    expect(nthRenderedOptionText(0)).toBe("C");
+
+    await toggleOption("C");
+    expect(nthRenderedOptionText(0)).toBe("A");
+  });
+
+  it("sorts newly-toggled items only after the dropdown is reoponed (with selectionFeedback: top-after-reopen)", async () => {
+    render(MultiSelect, {
+      items: [
+        { id: "3", text: "C" },
+        { id: "1", text: "A" },
+        { id: "2", text: "B" },
+      ],
+    });
+
+    // Initially, items should be sorted alphabetically.
+    await openMenu();
+    expect(nthRenderedOptionText(0)).toBe("A");
+
+    // While the menu is still open, a newly-selected item should not move.
+    await toggleOption("C");
+    expect(nthRenderedOptionText(0)).toBe("A");
+
+    // The newly-selected item should move after the menu is closed and
+    // re-opened.
+    await closeMenu();
+    await openMenu();
+    expect(nthRenderedOptionText(0)).toBe("C");
+
+    // A deselected item should not move while the dropdown is still open.
+    await toggleOption("C");
+    expect(nthRenderedOptionText(0)).toBe("C");
+
+    // The deselected item should move after closing and re-opening the dropdown.
+    await closeMenu();
+    await openMenu();
+    expect(nthRenderedOptionText(0)).toBe("A");
+  });
+
+  it("never moves selected items to the top (with selectionFeedback: fixed)", async () => {
+    render(MultiSelect, {
+      items: [
+        { id: "3", text: "C" },
+        { id: "1", text: "A" },
+        { id: "2", text: "B" },
+      ],
+      selectionFeedback: "fixed",
+    });
+
+    // Items should be sorted alphabetically.
+    await openMenu();
+    expect(nthRenderedOptionText(0)).toBe("A");
+
+    // A newly-selected item should not move after the selection is made.
+    await toggleOption("C");
+    expect(nthRenderedOptionText(0)).toBe("A");
+
+    // The newly-selected item also shouldn’t move after the dropdown is closed
+    // and reopened.
+    await closeMenu();
+    await openMenu();
+    expect(nthRenderedOptionText(0)).toBe("A");
+  });
+});
diff --git a/tests/setup-tests.ts b/tests/setup-tests.ts
index d494d2af..c69af710 100644
--- a/tests/setup-tests.ts
+++ b/tests/setup-tests.ts
@@ -3,4 +3,7 @@ import "@testing-library/jest-dom/vitest";
 import { userEvent } from "@testing-library/user-event";
 import "../css/all.css";
 
+// Mock scrollIntoView since it's not implemented in JSDOM
+Element.prototype.scrollIntoView = vi.fn();
+
 export const user = userEvent.setup();