fix(cli): allow using file resource synchronously while being used async (#15747)

1 files changed, 14 insertions, 0 deletions

diff --git a/cli/tests/testdata/run/stdout_write_sync_async.ts b/cli/tests/testdata/run/stdout_write_sync_async.ts
new file mode 100644
index 000000000..648999d8a
--- /dev/null
+++ b/cli/tests/testdata/run/stdout_write_sync_async.ts
@@ -0,0 +1,14 @@
+const encoder = new TextEncoder();
+const pending = [];
+
+for (let i = 0; i < 100; i++) {
+  // some code that will cause stdout to be written
+  // synchronously while the async write might be occurring
+  console.log("Hello");
+  pending.push(Deno.stdout.write(encoder.encode("Hello\n")));
+  if (i % 10) {
+    await new Promise((resolve) => setTimeout(resolve, 0));
+  }
+}
+
+await Promise.all(pending);