Keep WordUtils.wrap from splitting a surrogate pair

src/main/java/org/apache/commons/text/WordUtils.java

@@ -843,10 +843,14 @@ public static String wrap(final String str,
                 if (matcherSize == 0) {
                     offset--;
                 }
-                // wrap really long word one line at a time
-                wrappedLine.append(str, offset, wrapLength + offset);
+                // wrap really long word one line at a time, but keep a surrogate pair whole
+                int wrapAt = wrapLength + offset;
+                if (Character.isHighSurrogate(str.charAt(wrapAt - 1)) && Character.isLowSurrogate(str.charAt(wrapAt))) {
+                    wrapAt++;
+                }
+                wrappedLine.append(str, offset, wrapAt);
                 wrappedLine.append(newLineStr);
-                offset += wrapLength;
+                offset = wrapAt;
                 matcherSize = -1;
             } else {
                 // do not wrap really long word, just extend beyond limit

src/test/java/org/apache/commons/text/WordUtilsTest.java

@@ -543,6 +543,14 @@ void testWrap_StringIntStringBoolean() {
         assertEquals(expected, WordUtils.wrap(input, 20, "\n", false));
         expected = "Click here,\nhttps://commons.apac\nhe.org, to jump to\nthe commons website";
         assertEquals(expected, WordUtils.wrap(input, 20, "\n", true));
+
+        // a hard break for a long word must not split a surrogate pair across the new line
+        input = "a\uD83D\uDE00\uD83D\uDE00\uD83D\uDE00\uD83D\uDE00";
+        expected = "a\uD83D\uDE00\uD83D\uDE00\n\uD83D\uDE00\uD83D\uDE00";
+        assertEquals(expected, WordUtils.wrap(input, 4, "\n", true));
+        input = "\uD83D\uDE00\uD83D\uDE00\uD83D\uDE00";
+        expected = "\uD83D\uDE00\uD83D\uDE00\n\uD83D\uDE00";
+        assertEquals(expected, WordUtils.wrap(input, 3, "\n", true));
     }
 
     @Test