Fix split assertion logic in StringUtilsTest

Updated the assertSplit method to correctly handle delimiter length checks and assertions. Now, assertions for single-character and multi-character delimiters are separated, ensuring accurate test validation.

Author: mercyblitz

microsphere-java-core/src/test/java/io/microsphere/util/StringUtilsTest.java

@@ -111,11 +111,13 @@ void testSplit() {
 
     String[] assertSplit(String str, String delimiter) {
         String[] values = split(str, delimiter);
-        if (length(delimiter) == 1) {
+        int length = length(delimiter);
+        if (length == 1) {
             assertArrayEquals(split(str, delimiter.charAt(0)), values);
+        } else if (length > 1) {
+            String[] valuesFromString = delimitedListToStringArray(str, delimiter);
+            assertArrayEquals(valuesFromString, values);
         }
-        String[] valuesFromString = delimitedListToStringArray(str, delimiter);
-        assertArrayEquals(valuesFromString, values);
         return values;
     }