Allow 0-length ArrayBuffer & Blob in Bun.spawn stdio (#9557)

Co-authored-by: Zack Radisic <zack@theradisic.com>

src/bun.js/api/bun/spawn/stdio.zig

@@ -409,9 +409,10 @@ pub const Stdio = union(enum) {
                 }
             }
         } else if (value.asArrayBuffer(globalThis)) |array_buffer| {
-            if (array_buffer.slice().len == 0) {
-                globalThis.throwInvalidArguments("ArrayBuffer cannot be empty", .{});
-                return false;
+            // Change in Bun v1.0.34: don't throw for empty ArrayBuffer
+            if (array_buffer.byteSlice().len == 0) {
+                out_stdio.* = .{ .ignore = {} };
+                return true;
             }
 
             out_stdio.* = .{
@@ -475,6 +476,12 @@ pub const Stdio = union(enum) {
             return false;
         }
 
+        // Instead of writing an empty blob, lets just make it /dev/null
+        if (blob.fastSize() == 0) {
+            stdio.* = .{ .ignore = {} };
+            return true;
+        }
+
         stdio.* = .{ .blob = blob };
         return true;
     }

test/js/bun/spawn/spawn-empty-arrayBufferOrBlob.test.ts

@@ -0,0 +1,29 @@
+import { describe, test, expect } from "bun:test";
+import { bunEnv, bunExe } from "harness";
+
+describe("spawn with empty", () => {
+  for (const [stdin, label] of [
+    [new ArrayBuffer(0), "ArrayBuffer"],
+    [new Uint8Array(0), "Uint8Array"],
+    [new Blob([]), "Blob"],
+  ] as const) {
+    test(label + " for stdin", async () => {
+      const proc = Bun.spawn({
+        cmd: [bunExe(), "-e", "process.stdin.pipe(process.stdout)"],
+        stdin,
+        stdout: "pipe",
+        stderr: "pipe",
+        env: bunEnv,
+      });
+
+      const [exited, stdout, stderr] = await Promise.all([
+        proc.exited,
+        new Response(proc.stdout).text(),
+        new Response(proc.stderr).text(),
+      ]);
+      expect(exited).toBe(0);
+      expect(stdout).toBeEmpty();
+      expect(stderr).toBeEmpty();
+    });
+  }
+});