[String] Fix width method in AbstractUnicodeString

Author: TBoileau

AbstractUnicodeString.php

@@ -498,8 +498,11 @@ public function width(bool $ignoreAnsiDecoration = true): int
                 )|[\p{Cc}\x7F]++)/xu', '', $s);
             }
 
-            // Non printable characters have been dropped, so wcswidth cannot logically return -1.
-            $width += $this->wcswidth($s);
+            $lineWidth = $this->wcswidth($s);
+
+            if ($lineWidth > $width) {
+                $width = $lineWidth;
+            }
         }
 
         return $width;

Tests/AbstractUnicodeTestCase.php

@@ -15,6 +15,19 @@
 
 abstract class AbstractUnicodeTestCase extends AbstractAsciiTestCase
 {
+    public static function provideWidth(): array
+    {
+        return array_merge(
+            parent::provideWidth(),
+            [
+                [14, '<<<END
+This is a
+multiline text
+END'],
+            ]
+        );
+    }
+
     public function testCreateFromStringWithInvalidUtf8Input()
     {
         $this->expectException(InvalidArgumentException::class);