From 16b770c578d1c6cad87b259a1766a86db0792b20 Mon Sep 17 00:00:00 2001
From: Ting-Yu Lin <aethanyc@gmail.com>
Date: Mon, 8 Apr 2024 12:08:21 -0700
Subject: [PATCH] Add a grapheme cluster test for emoji flags (#4781)

Fixed #4780.
---
 components/segmenter/src/grapheme.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/components/segmenter/src/grapheme.rs b/components/segmenter/src/grapheme.rs
index 9cfe0349bcf..8bbeacfe20a 100644
--- a/components/segmenter/src/grapheme.rs
+++ b/components/segmenter/src/grapheme.rs
@@ -268,3 +268,11 @@ fn empty_string() {
     let breaks: Vec<usize> = segmenter.segment_str("").collect();
     assert_eq!(breaks, [0]);
 }
+
+#[test]
+fn emoji_flags() {
+    // https://github.com/unicode-org/icu4x/issues/4780
+    let segmenter = GraphemeClusterSegmenter::new();
+    let breaks: Vec<usize> = segmenter.segment_str("🇺🇸🏴󠁧󠁢󠁥󠁮󠁧󠁿").collect();
+    assert_eq!(breaks, [0, 8, 36]);
+}