From 108ae1c822402cca76ab5ee8ec5acd61ba77b121 Mon Sep 17 00:00:00 2001
From: Farnabaz <farnabaz@gmail.com>
Date: Fri, 21 Aug 2026 15:01:24 +0200
Subject: [PATCH] test: cover in-place streamed code block content updates

Add a regression test from #583 ensuring fenced code blocks re-render when
their content changes without moving in the document.

Co-authored-by: Kinfe123 <kinfishtech@gmail.com>
---
 .../__tests__/code-block-memo.test.tsx        | 24 +++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/packages/streamdown/__tests__/code-block-memo.test.tsx b/packages/streamdown/__tests__/code-block-memo.test.tsx
index 4c8675df..3bb020e3 100644
--- a/packages/streamdown/__tests__/code-block-memo.test.tsx
+++ b/packages/streamdown/__tests__/code-block-memo.test.tsx
@@ -18,6 +18,30 @@ vi.mock("../lib/code-block", () => ({
 }));
 
 describe("MemoCode in streaming mode", () => {
+  it("should re-render code blocks when their content changes in place", async () => {
+    codeBlockRenderCount = 0;
+
+    const initial = "```js\nfirst\n```";
+    const updated = "```js\nsecond\n```";
+
+    const { container, rerender } = render(<Streamdown>{initial}</Streamdown>);
+
+    await waitFor(() => {
+      expect(container.textContent).toContain("first");
+    });
+
+    const initialRenderCount = codeBlockRenderCount;
+
+    rerender(<Streamdown>{updated}</Streamdown>);
+
+    await waitFor(() => {
+      expect(container.textContent).toContain("second");
+    });
+
+    expect(container.textContent).not.toContain("first");
+    expect(codeBlockRenderCount).toBeGreaterThan(initialRenderCount);
+  });
+
   it("should not re-render unchanged code blocks on streaming updates", async () => {
     codeBlockRenderCount = 0;