Do not rely on Formatter in the debug prints of RegexEngineTest.

sjrd · sjrd · commit eae9211e377a · 2025-06-16T18:06:56.000+02:00
`Formatter` is an entire beast of its own. It is a poor fit for
the debugging output of another area of the test suite.
diff --git a/test-suite/shared/src/test/scala/org/scalajs/testsuite/javalib/util/regex/RegexEngineTest.scala b/test-suite/shared/src/test/scala/org/scalajs/testsuite/javalib/util/regex/RegexEngineTest.scala
@@ -54,11 +54,12 @@ class RegexEngineTest  {
 
   private def debugEscape(pattern: String): String = {
     pattern.flatMap {
-      case '\t'         => "`t"
-      case '\n'         => "`n"
-      case '\r'         => "`r"
-      case c if c < ' ' => "`x%02X".format(c.toInt)
-      case c            => c.toString()
+      case '\t'          => "`t"
+      case '\n'          => "`n"
+      case '\r'          => "`r"
+      case c if c < 0x10 => "`x0" + c.toInt.toHexString
+      case c if c < ' '  => "`x" + c.toInt.toHexString
+      case c             => c.toString()
     }
   }
 
