feat: add extensive test suite

lib/abort.test.ts

@@ -0,0 +1,38 @@
+import { describe, expect, mock, test } from "bun:test";
+import { registerAbortCleanup } from "./abort";
+
+describe("abort cleanup", () => {
+  test("runs once when a signal aborts", () => {
+    const controller = new AbortController();
+    const cleanup = mock(() => {});
+    registerAbortCleanup(controller.signal, cleanup);
+    controller.abort();
+    controller.abort();
+    expect(cleanup).toHaveBeenCalledTimes(1);
+  });
+
+  test("runs immediately for an already-aborted health request", () => {
+    const controller = new AbortController();
+    controller.abort();
+    const cleanup = mock(() => {});
+    const remove = registerAbortCleanup(controller.signal, cleanup);
+    expect(cleanup).toHaveBeenCalledTimes(1);
+    remove();
+  });
+
+  test("returns a harmless cleanup without a signal", () => {
+    const cleanup = mock(() => {});
+    const remove = registerAbortCleanup(undefined, cleanup);
+    remove();
+    expect(cleanup).not.toHaveBeenCalled();
+  });
+
+  test("returned cleanup removes the abort listener", () => {
+    const controller = new AbortController();
+    const cleanup = mock(() => {});
+    const remove = registerAbortCleanup(controller.signal, cleanup);
+    remove();
+    controller.abort();
+    expect(cleanup).not.toHaveBeenCalled();
+  });
+});