test: dedupe fetch cleanup-throw signal harness

src/infra/fetch.test.ts

@@ -31,6 +31,18 @@ function createForeignSignalHarness() {
   };
 }
 
+function createThrowingCleanupSignalHarness(cleanupError: Error) {
+  const removeEventListener = vi.fn(() => {
+    throw cleanupError;
+  });
+  const fakeSignal = {
+    aborted: false,
+    addEventListener: (_event: string, _handler: () => void) => {},
+    removeEventListener,
+  } as unknown as AbortSignal;
+  return { fakeSignal, removeEventListener };
+}
+
 describe("wrapFetchWithAbortSignal", () => {
   it("adds duplex for requests with a body", async () => {
     let seenInit: RequestInit | undefined;
@@ -122,15 +134,7 @@ describe("wrapFetchWithAbortSignal", () => {
     );
     const wrapped = wrapFetchWithAbortSignal(fetchImpl);
 
-    const removeEventListener = vi.fn(() => {
+    const { fakeSignal, removeEventListener } = createThrowingCleanupSignalHarness(cleanupError);
-      throw cleanupError;
-    });
-
-    const fakeSignal = {
-      aborted: false,
-      addEventListener: (_event: string, _handler: () => void) => {},
-      removeEventListener,
-    } as unknown as AbortSignal;
 
     await expect(wrapped("https://example.com", { signal: fakeSignal })).rejects.toBe(fetchError);
     expect(removeEventListener).toHaveBeenCalledOnce();
@@ -146,15 +150,7 @@ describe("wrapFetchWithAbortSignal", () => {
     );
     const wrapped = wrapFetchWithAbortSignal(fetchImpl);
 
-    const removeEventListener = vi.fn(() => {
+    const { fakeSignal, removeEventListener } = createThrowingCleanupSignalHarness(cleanupError);
-      throw cleanupError;
-    });
-
-    const fakeSignal = {
-      aborted: false,
-      addEventListener: (_event: string, _handler: () => void) => {},
-      removeEventListener,
-    } as unknown as AbortSignal;
 
     expect(() => wrapped("https://example.com", { signal: fakeSignal })).toThrow(syncError);
     expect(removeEventListener).toHaveBeenCalledOnce();