Announce unavailable controls instead of hiding them behind disabled

Native `disabled` removes an element from the tab order and from the accessibility tree, so any explanation of why a control cannot be used is delivered only to a sighted user with a mouse. `useUnavailable` is the way out: `aria-disabled` keeps the control focusable and announced, `aria-describedby` carries the reason, and — because `aria-disabled` is advisory and blocks nothing — the hook hands back the click and Enter/Space guards along with the attributes, so a call site cannot take the announcement without the guard. `Button` gets it as an opt-in `unavailable` / `unavailableReason` pair. Opt-in matters: 37 files render this button and none of them change. The `aria-disabled:` class mirrors exist because Tailwind's `disabled:` variant only matches the native attribute, which this pattern deliberately omits. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_011YPqHpjV4EL6RNEwrRKqQm
2026-09-02 09:08:50 -07:00
parent ed1dc8502c
commit aa0a574091
3 changed files with 205 additions and 11 deletions
@@ -0,0 +1,77 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { render, screen, fireEvent } from "@testing-library/react";
+import Button from "./Button";
+
+const onClick = vi.fn();
+const onKeyDown = vi.fn();
+
+describe("Button", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("still supports the native disabled attribute", () => {
+    render(
+      <Button disabled onClick={onClick}>
+        Save
+      </Button>,
+    );
+    expect(screen.getByRole("button", { name: "Save" })).toBeDisabled();
+  });
+
+  it("stays in the accessibility tree when unavailable, and says why", () => {
+    render(
+      <Button unavailable unavailableReason="Stop the container first.">
+        Save
+      </Button>,
+    );
+    const button = screen.getByRole("button", { name: "Save" });
+    expect(button).not.toBeDisabled();
+    expect(button).toHaveAttribute("aria-disabled", "true");
+    expect(button).toHaveAccessibleDescription("Stop the container first.");
+    // The reason is a description, not part of the name.
+    expect(button).toHaveAccessibleName("Save");
+  });
+
+  it("guards clicks and Enter/Space while unavailable", () => {
+    render(
+      <Button unavailable unavailableReason="Stop the container first." onClick={onClick}>
+        Save
+      </Button>,
+    );
+    const button = screen.getByRole("button", { name: "Save" });
+    fireEvent.click(button);
+    fireEvent.keyDown(button, { key: "Enter" });
+    fireEvent.keyDown(button, { key: " " });
+    expect(onClick).not.toHaveBeenCalled();
+  });
+
+  it("still forwards keys that are not activation keys", () => {
+    render(
+      <Button
+        unavailable
+        unavailableReason="Stop the container first."
+        onKeyDown={onKeyDown}
+      >
+        Save
+      </Button>,
+    );
+    fireEvent.keyDown(screen.getByRole("button", { name: "Save" }), {
+      key: "Escape",
+    });
+    expect(onKeyDown).toHaveBeenCalled();
+  });
+
+  it("behaves like an ordinary button when available", () => {
+    render(
+      <Button unavailable={false} unavailableReason="Stop the container first." onClick={onClick}>
+        Save
+      </Button>,
+    );
+    const button = screen.getByRole("button", { name: "Save" });
+    expect(button).not.toHaveAttribute("aria-disabled");
+    expect(button).toHaveAccessibleDescription("");
+    fireEvent.click(button);
+    expect(onClick).toHaveBeenCalledTimes(1);
+  });
+});