Merge pull request #239 from RtlZeroMemory/fix/232-text-wrap-newlines

test(core): lock newline wrap rendering behavior

Author: RtlZeroMemory

packages/core/src/renderer/__tests__/renderer.text.test.ts

@@ -11,10 +11,11 @@ import {
   parseCommandHeaders,
   parseInternedStrings,
 } from "../../__tests__/drawlistDecode.js";
-import { type VNode, createDrawlistBuilder } from "../../index.js";
+import { type VNode, createDrawlistBuilder, ui } from "../../index.js";
 import { layout } from "../../layout/layout.js";
 import { commitVNodeTree } from "../../runtime/commit.js";
 import { createInstanceIdAllocator } from "../../runtime/instance.js";
+import { createTestRenderer } from "../../testing/renderer.js";
 import { renderToDrawlist } from "../renderToDrawlist.js";
 
 const decoder = new TextDecoder();
@@ -296,6 +297,47 @@ function expectBlob(frame: ParsedFrame, blobIndex: number): TextRunBlob {
   return blob;
 }
 
+describe("renderer text - wrap newline handling", () => {
+  test("wrap=true renders explicit newline lines on separate rows", () => {
+    const renderer = createTestRenderer({ viewport: { cols: 20, rows: 4 } });
+    const frame = renderer.render(
+      ui.text("First line\nSecond line", {
+        id: "wrapped",
+        wrap: true,
+      }),
+    );
+    const lines = frame.toText().split("\n");
+
+    assert.equal(lines[0]?.includes("First line"), true);
+    assert.equal(lines[1]?.includes("Second line"), true);
+
+    const wrapped = frame.findById("wrapped");
+    assert.notEqual(wrapped, null);
+    assert.equal(wrapped?.rect.y, 0);
+    assert.ok((wrapped?.rect.h ?? 0) >= 2);
+  });
+
+  test("wrap=true preserves blank lines from double newlines", () => {
+    const renderer = createTestRenderer({ viewport: { cols: 20, rows: 6 } });
+    const frame = renderer.render(
+      ui.text("Alpha\n\nOmega", {
+        id: "wrapped-blank",
+        wrap: true,
+      }),
+    );
+    const lines = frame.toText().split("\n");
+
+    assert.equal(lines[0]?.includes("Alpha"), true);
+    assert.equal((lines[1] ?? "").trim(), "");
+    assert.equal(lines[2]?.includes("Omega"), true);
+
+    const wrapped = frame.findById("wrapped-blank");
+    assert.notEqual(wrapped, null);
+    assert.equal(wrapped?.rect.y, 0);
+    assert.ok((wrapped?.rect.h ?? 0) >= 3);
+  });
+});
+
 describe("renderer text - transform ANSI styling", () => {
   const gradientTransform = (): string => "\u001b[31mA\u001b[32mB\u001b[0m";