fix(console): properly identify Generator and AsyncGenerator in console.log

src/bun.js/ConsoleObject.zig

@@ -1338,6 +1338,8 @@ pub const Formatter = struct {
                     .JSArrayIterator,
                     .Iterator,
                     .IteratorHelper,
+                    .Generator,
+                    .AsyncGenerator,
                     .Object,
                     .FinalObject,
                     .ModuleNamespaceObject,

test/regression/issue/18324.test.ts

@@ -0,0 +1,134 @@
+import { test, expect } from "bun:test";
+import { bunEnv, bunExe } from "harness";
+
+// Issue #18324: Async generator function are not properly identified in console.log
+// https://github.com/oven-sh/bun/issues/18324
+//
+// When logging an async generator, Bun shows `{}` instead of something like
+// `Object [AsyncGenerator] {}` (Node.js) or `AsyncGenerator {}`.
+
+test("console.log should properly identify async generator objects", async () => {
+  await using proc = Bun.spawn({
+    cmd: [
+      bunExe(),
+      "-e",
+      `
+async function* arrayToIter(requests) {
+  for (const request of requests) {
+    yield await Promise.resolve(request);
+  }
+}
+console.log(arrayToIter([]));
+`,
+    ],
+    env: bunEnv,
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+
+  const [stdout, stderr, exitCode] = await Promise.all([
+    proc.stdout.text(),
+    proc.stderr.text(),
+    proc.exited,
+  ]);
+
+  // Should NOT be just `{}` - should contain some identifier for AsyncGenerator
+  expect(stdout.trim()).not.toBe("{}");
+  // Should contain "AsyncGenerator" in the output
+  expect(stdout).toContain("AsyncGenerator");
+
+  expect(exitCode).toBe(0);
+});
+
+test("console.log should properly identify regular generator objects", async () => {
+  await using proc = Bun.spawn({
+    cmd: [
+      bunExe(),
+      "-e",
+      `
+function* gen() {
+  yield 1;
+  yield 2;
+}
+console.log(gen());
+`,
+    ],
+    env: bunEnv,
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+
+  const [stdout, stderr, exitCode] = await Promise.all([
+    proc.stdout.text(),
+    proc.stderr.text(),
+    proc.exited,
+  ]);
+
+  // Should NOT be just `{}` - should contain some identifier for Generator
+  expect(stdout.trim()).not.toBe("{}");
+  // Should contain "Generator" in the output
+  expect(stdout).toContain("Generator");
+
+  expect(exitCode).toBe(0);
+});
+
+test("console.log shows generator state when it has yielded values", async () => {
+  await using proc = Bun.spawn({
+    cmd: [
+      bunExe(),
+      "-e",
+      `
+async function* asyncGen() {
+  yield 1;
+  yield 2;
+}
+const g = asyncGen();
+await g.next(); // consume first value
+console.log(g);
+`,
+    ],
+    env: bunEnv,
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+
+  const [stdout, stderr, exitCode] = await Promise.all([
+    proc.stdout.text(),
+    proc.stderr.text(),
+    proc.exited,
+  ]);
+
+  // Should contain AsyncGenerator identifier
+  expect(stdout).toContain("AsyncGenerator");
+
+  expect(exitCode).toBe(0);
+});
+
+test("Bun.inspect should properly identify async generator", async () => {
+  await using proc = Bun.spawn({
+    cmd: [
+      bunExe(),
+      "-e",
+      `
+async function* asyncGen() {
+  yield 1;
+}
+console.log(Bun.inspect(asyncGen()));
+`,
+    ],
+    env: bunEnv,
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+
+  const [stdout, stderr, exitCode] = await Promise.all([
+    proc.stdout.text(),
+    proc.stderr.text(),
+    proc.exited,
+  ]);
+
+  // Should contain AsyncGenerator identifier
+  expect(stdout).toContain("AsyncGenerator");
+
+  expect(exitCode).toBe(0);
+});