test(browser): dedupe CDP and download setup helpers

src/browser/cdp.test.ts

@@ -1,6 +1,6 @@
 import { createServer } from "node:http";
 import { afterEach, describe, expect, it } from "vitest";
-import { WebSocketServer } from "ws";
+import { type WebSocket, WebSocketServer } from "ws";
 import { rawDataToString } from "../infra/ws.js";
 import { createTargetViaCdp, evaluateJavaScript, normalizeCdpWsUrl, snapshotAria } from "./cdp.js";
 
@@ -14,6 +14,29 @@ describe("cdp", () => {
     return (wsServer.address() as { port: number }).port;
   };
 
+  const startWsServerWithMessages = async (
+    onMessage: (
+      msg: { id?: number; method?: string; params?: Record<string, unknown> },
+      socket: WebSocket,
+    ) => void,
+  ) => {
+    const wsPort = await startWsServer();
+    if (!wsServer) {
+      throw new Error("ws server not initialized");
+    }
+    wsServer.on("connection", (socket) => {
+      socket.on("message", (data) => {
+        const msg = JSON.parse(rawDataToString(data)) as {
+          id?: number;
+          method?: string;
+          params?: Record<string, unknown>;
+        };
+        onMessage(msg, socket);
+      });
+    });
+    return wsPort;
+  };
+
   afterEach(async () => {
     await new Promise<void>((resolve) => {
       if (!httpServer) {
@@ -32,18 +55,7 @@ describe("cdp", () => {
   });
 
   it("creates a target via the browser websocket", async () => {
-    const wsPort = await startWsServer();
+    const wsPort = await startWsServerWithMessages((msg, socket) => {
-    if (!wsServer) {
-      throw new Error("ws server not initialized");
-    }
-
-    wsServer.on("connection", (socket) => {
-      socket.on("message", (data) => {
-        const msg = JSON.parse(rawDataToString(data)) as {
-          id?: number;
-          method?: string;
-          params?: { url?: string };
-        };
       if (msg.method !== "Target.createTarget") {
         return;
       }
@@ -54,7 +66,6 @@ describe("cdp", () => {
         }),
       );
     });
-    });
 
     httpServer = createServer((req, res) => {
       if (req.url === "/json/version") {
@@ -82,18 +93,7 @@ describe("cdp", () => {
   });
 
   it("evaluates javascript via CDP", async () => {
-    const wsPort = await startWsServer();
+    const wsPort = await startWsServerWithMessages((msg, socket) => {
-    if (!wsServer) {
-      throw new Error("ws server not initialized");
-    }
-
-    wsServer.on("connection", (socket) => {
-      socket.on("message", (data) => {
-        const msg = JSON.parse(rawDataToString(data)) as {
-          id?: number;
-          method?: string;
-          params?: { expression?: string };
-        };
       if (msg.method === "Runtime.enable") {
         socket.send(JSON.stringify({ id: msg.id, result: {} }));
         return;
@@ -108,7 +108,6 @@ describe("cdp", () => {
         );
       }
     });
-    });
 
     const res = await evaluateJavaScript({
       wsUrl: `ws://127.0.0.1:${wsPort}`,
@@ -120,17 +119,7 @@ describe("cdp", () => {
   });
 
   it("captures an aria snapshot via CDP", async () => {
-    const wsPort = await startWsServer();
+    const wsPort = await startWsServerWithMessages((msg, socket) => {
-    if (!wsServer) {
-      throw new Error("ws server not initialized");
-    }
-
-    wsServer.on("connection", (socket) => {
-      socket.on("message", (data) => {
-        const msg = JSON.parse(rawDataToString(data)) as {
-          id?: number;
-          method?: string;
-        };
       if (msg.method === "Accessibility.enable") {
         socket.send(JSON.stringify({ id: msg.id, result: {} }));
         return;
@@ -158,10 +147,8 @@ describe("cdp", () => {
             },
           }),
         );
-          return;
       }
     });
-    });
 
     const snap = await snapshotAria({ wsUrl: `ws://127.0.0.1:${wsPort}` });
     expect(snap.nodes.length).toBe(2);

src/browser/pw-tools-core.waits-next-download-saves-it.test.ts

@@ -27,15 +27,8 @@ describe("pw-tools-core", () => {
     downloadUrl: string;
     suggestedFilename: string;
   }) {
-    let downloadHandler: ((download: unknown) => void) | undefined;
+    const harness = createDownloadEventHarness();
-    const on = vi.fn((event: string, handler: (download: unknown) => void) => {
-      if (event === "download") {
-        downloadHandler = handler;
-      }
-    });
-    const off = vi.fn();
     const saveAs = vi.fn(async () => {});
-    setPwToolsCoreCurrentPage({ on, off });
 
     const p = mod.waitForDownloadViaPlaywright({
       cdpUrl: "http://127.0.0.1:18792",
@@ -44,7 +37,7 @@ describe("pw-tools-core", () => {
     });
 
     await Promise.resolve();
-    downloadHandler?.({
+    harness.trigger({
       url: () => params.downloadUrl,
       suggestedFilename: () => params.suggestedFilename,
       saveAs,
@@ -55,7 +48,7 @@ describe("pw-tools-core", () => {
     return { res, outPath };
   }
 
-  it("waits for the next download and saves it", async () => {
+  function createDownloadEventHarness() {
     let downloadHandler: ((download: unknown) => void) | undefined;
     const on = vi.fn((event: string, handler: (download: unknown) => void) => {
       if (event === "download") {
@@ -63,6 +56,19 @@ describe("pw-tools-core", () => {
       }
     });
     const off = vi.fn();
+    setPwToolsCoreCurrentPage({ on, off });
+    return {
+      trigger: (download: unknown) => {
+        downloadHandler?.(download);
+      },
+      expectArmed: () => {
+        expect(downloadHandler).toBeDefined();
+      },
+    };
+  }
+
+  it("waits for the next download and saves it", async () => {
+    const harness = createDownloadEventHarness();
 
     const saveAs = vi.fn(async () => {});
     const download = {
@@ -71,8 +77,6 @@ describe("pw-tools-core", () => {
       saveAs,
     };
 
-    setPwToolsCoreCurrentPage({ on, off });
-
     const targetPath = path.resolve("/tmp/file.bin");
     const p = mod.waitForDownloadViaPlaywright({
       cdpUrl: "http://127.0.0.1:18792",
@@ -82,21 +86,15 @@ describe("pw-tools-core", () => {
     });
 
     await Promise.resolve();
-    expect(downloadHandler).toBeDefined();
+    harness.expectArmed();
-    downloadHandler?.(download);
+    harness.trigger(download);
 
     const res = await p;
     expect(saveAs).toHaveBeenCalledWith(targetPath);
     expect(res.path).toBe(targetPath);
   });
   it("clicks a ref and saves the resulting download", async () => {
-    let downloadHandler: ((download: unknown) => void) | undefined;
+    const harness = createDownloadEventHarness();
-    const on = vi.fn((event: string, handler: (download: unknown) => void) => {
-      if (event === "download") {
-        downloadHandler = handler;
-      }
-    });
-    const off = vi.fn();
 
     const click = vi.fn(async () => {});
     setPwToolsCoreCurrentRefLocator({ click });
@@ -108,8 +106,6 @@ describe("pw-tools-core", () => {
       saveAs,
     };
 
-    setPwToolsCoreCurrentPage({ on, off });
-
     const targetPath = path.resolve("/tmp/report.pdf");
     const p = mod.downloadViaPlaywright({
       cdpUrl: "http://127.0.0.1:18792",
@@ -120,10 +116,10 @@ describe("pw-tools-core", () => {
     });
 
     await Promise.resolve();
-    expect(downloadHandler).toBeDefined();
+    harness.expectArmed();
     expect(click).toHaveBeenCalledWith({ timeout: 1000 });
 
-    downloadHandler?.(download);
+    harness.trigger(download);
 
     const res = await p;
     expect(saveAs).toHaveBeenCalledWith(targetPath);