fix(ext/fetch): do not truncate field value in `EventSource` (#22368)

Depends on #22493. Closes #22367.

1 files changed, 27 insertions, 0 deletions

diff --git a/tests/unit/event_source_test.ts b/tests/unit/event_source_test.ts
new file mode 100644
index 000000000..242c12d6e
--- /dev/null
+++ b/tests/unit/event_source_test.ts
@@ -0,0 +1,27 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+import { assertStrictEquals } from "./test_util.ts";
+
+Deno.test(
+  { permissions: { net: ["127.0.0.1"] } },
+  async function eventSourceColonInMessage() {
+    const portDeferred = Promise.withResolvers<number>();
+
+    await using _server = Deno.serve({
+      handler: () =>
+        new Response('data: {"key":"value"}\n\n', {
+          headers: { "content-type": "text/event-stream" },
+        }),
+      onListen: ({ port }) => portDeferred.resolve(port),
+      hostname: "127.0.0.1",
+      port: 0,
+    });
+
+    const port = await portDeferred.promise;
+    const eventSource = new EventSource(`http://127.0.0.1:${port}/`);
+    const event = await new Promise<MessageEvent>((resolve) =>
+      eventSource.onmessage = resolve
+    );
+    eventSource.close();
+    assertStrictEquals(event.data, '{"key":"value"}');
+  },
+);