test: add regression test for Tailwind v4 rem propagation fix

Author: maxencehenneron

src/__tests__/native/units.test.tsx

@@ -148,6 +148,31 @@ test("rem - css root font-size override", () => {
   });
 });
 
+test("rem - via var() inlining picks up css root font-size (Tailwind v4 style)", () => {
+  // Regression test for the second-pass parseLength bug.
+  // Tailwind v4 emits utilities as `:root { --text-base: 1rem }` +
+  // `.text-base { font-size: var(--text-base) }`. The `1rem` inside
+  // the custom property is a token-list that skips the first-pass
+  // Length visitor and gets resolved later by parseLength, which
+  // reads inlineRem from the builder's options. Without the fix
+  // that writes regex-discovered rem back to options, parseLength
+  // falls back to 14 and this resolves to `fontSize: 14`.
+  registerCSS(`
+    :root { font-size: 16px; --text-base: 1rem; }
+    .text-base { font-size: var(--text-base); }
+  `);
+
+  const { result } = renderHook(() => {
+    return useNativeCss(View, { className: "text-base" });
+  });
+
+  expect(result.current.type).toBe(VariableContext.Provider);
+  expect(result.current.props.children.type).toBe(View);
+  expect(result.current.props.children.props).toStrictEqual({
+    style: { fontSize: 16 },
+  });
+});
+
 test("rem - css override", () => {
   registerCSS(
     `