From d923f29e5ab585d8514a53a1cf73970e9f5ddaa6 Mon Sep 17 00:00:00 2001
From: Seongho Bae <me@seonghobae.me>
Date: Tue, 11 Aug 2026 13:22:02 +0900
Subject: [PATCH] test(reliability): define Blob size preflight RED

---
 src/converter/blobSizePreflight.test.ts | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100644 src/converter/blobSizePreflight.test.ts

diff --git a/src/converter/blobSizePreflight.test.ts b/src/converter/blobSizePreflight.test.ts
new file mode 100644
index 00000000..4c673d56
--- /dev/null
+++ b/src/converter/blobSizePreflight.test.ts
@@ -0,0 +1,21 @@
+import { describe, expect, it, vi } from 'vitest';
+
+import { Base64SizeError, blobToDataUri } from './index.js';
+
+describe('Blob conversion resource preflight', () => {
+  it('rejects a known oversized Blob before reading its payload bytes', async () => {
+    const blob = new Blob([new Uint8Array(32)], { type: 'application/octet-stream' });
+    const read = vi.fn(async () => new Uint8Array(32).buffer);
+    Object.defineProperty(blob, 'arrayBuffer', {
+      configurable: true,
+      value: read,
+    });
+
+    await expect(blobToDataUri(blob, { maxBytes: 4 })).rejects.toMatchObject({
+      name: 'Base64SizeError',
+      bytes: 32,
+      maxBytes: 4,
+    } satisfies Partial<Base64SizeError>);
+    expect(read).not.toHaveBeenCalled();
+  });
+});