diff --git a/src/common/StringUtilsTestCase.java b/src/common/StringUtilsTestCase.rs
similarity index 66%
rename from src/common/StringUtilsTestCase.java
rename to src/common/StringUtilsTestCase.rs
index f845148..3317741 100644
--- a/src/common/StringUtilsTestCase.java
+++ b/src/common/StringUtilsTestCase.rs
@@ -14,58 +14,61 @@
  * limitations under the License.
  */
 
-package com.google.zxing.common;
+// package com.google.zxing.common;
 
-import org.junit.Assert;
-import org.junit.Test;
+// import org.junit.Assert;
+// import org.junit.Test;
 
-import java.nio.charset.Charset;
-import java.nio.charset.StandardCharsets;
-import java.util.Random;
+// import java.nio.charset.Charset;
+// import java.nio.charset.StandardCharsets;
+// import java.util.Random;
 
-/**
- * Tests {@link StringUtils}.
- */
-public final class StringUtilsTestCase extends Assert {
+use rand::{Rng};
+use encoding::{Encoding};
+use std::{collections::HashMap, hash::Hash};
 
-  @Test
-  public void testRandom() {
-    Random r = new Random(1234L);
-    byte[] bytes = new byte[1000];
-    r.nextBytes(bytes);
-    assertEquals(Charset.defaultCharset(), StringUtils.guessCharset(bytes, null));
+use crate::common::StringUtils;
+
+  #[test]
+  fn testRandom() {
+    let mut r = rand::thread_rng();
+    let bytes : Vec<u8> = vec![0;1000];
+    for i in 0..bytes.len() {
+      bytes[i] = r.gen();
+    }
+    assert_eq!(encoding::all::UTF_8.name(), StringUtils::guessCharset(&bytes, HashMap::new()).name());
   }
 
-  @Test
-  public void testShortShiftJIS1() {
+  #[test]
+  fn testShortShiftJIS1() {
     // 金魚
-    doTest(new byte[] { (byte) 0x8b, (byte) 0xe0, (byte) 0x8b, (byte) 0x9b, }, StringUtils.SHIFT_JIS_CHARSET, "SJIS");
+    doTest(&vec![ 0x8b,  0xe0,  0x8b,  0x9b, ], encoding::label::encoding_from_whatwg_label("SJIS").unwrap(), "SJIS");
   }
 
-  @Test
-  public void testShortISO885911() {
+  #[test]
+  fn testShortISO885911() {
     // båd
     doTest(new byte[] { (byte) 0x62, (byte) 0xe5, (byte) 0x64, }, StandardCharsets.ISO_8859_1, "ISO8859_1");
   }
 
-  @Test
-  public void testShortUTF81() {
+  #[test]
+  fn  testShortUTF81() {
     // Español
     doTest(new byte[] { (byte) 0x45, (byte) 0x73, (byte) 0x70, (byte) 0x61, (byte) 0xc3,
                         (byte) 0xb1, (byte) 0x6f, (byte) 0x6c },
            StandardCharsets.UTF_8, "UTF8");
   }
 
-  @Test
-  public void testMixedShiftJIS1() {
+  #[test]
+  fn testMixedShiftJIS1() {
     // Hello 金!
     doTest(new byte[] { (byte) 0x48, (byte) 0x65, (byte) 0x6c, (byte) 0x6c, (byte) 0x6f,
                         (byte) 0x20, (byte) 0x8b, (byte) 0xe0, (byte) 0x21, },
            StringUtils.SHIFT_JIS_CHARSET, "SJIS");
   }
 
-  @Test
-  public void testUTF16BE() {
+  #[test]
+  fn testUTF16BE() {
     // 调压柜
     doTest(new byte[] { (byte) 0xFE, (byte) 0xFF, (byte) 0x8c, (byte) 0x03, (byte) 0x53, (byte) 0x8b,
                         (byte) 0x67, (byte) 0xdc, },
@@ -73,8 +76,8 @@ public final class StringUtilsTestCase extends Assert {
            StandardCharsets.UTF_16.name());
   }
 
-  @Test
-  public void testUTF16LE() {
+  #[test]
+  fn testUTF16LE() {
     // 调压柜
     doTest(new byte[] { (byte) 0xFF, (byte) 0xFE, (byte) 0x03, (byte) 0x8c, (byte) 0x8b, (byte) 0x53,
                         (byte) 0xdc, (byte) 0x67, },
@@ -82,11 +85,11 @@ public final class StringUtilsTestCase extends Assert {
            StandardCharsets.UTF_16.name());
   }
 
-  private static void doTest(byte[] bytes, Charset charset, String encoding) {
-    Charset guessedCharset = StringUtils.guessCharset(bytes, null);
-    String guessedEncoding = StringUtils.guessEncoding(bytes, null);
-    assertEquals(charset, guessedCharset);
-    assertEquals(encoding, guessedEncoding);
+  fn doTest(bytes :&Vec<u8>,  charset : &dyn Encoding,  encoding: &str) {
+    let guessedCharset = StringUtils::guessCharset(bytes, HashMap::new());
+    let guessedEncoding = StringUtils::guessEncoding(bytes, HashMap::new());
+    assert_eq!(charset.name(), guessedCharset.name());
+    assert_eq!(encoding, guessedEncoding);
   }
 
   /**
@@ -96,7 +99,7 @@ public final class StringUtilsTestCase extends Assert {
    *
    * @param args command line arguments
    */
-  public static void main(String[] args) {
+  fn main(String[] args) {
     String text = args[0];
     Charset charset = Charset.forName(args[1]);
     StringBuilder declaration = new StringBuilder();
@@ -114,4 +117,4 @@ public final class StringUtilsTestCase extends Assert {
     System.out.println(declaration);
   }
 
-}
+// }
diff --git a/src/common/mod.rs b/src/common/mod.rs
index 3859af3..2e5a7f1 100644
--- a/src/common/mod.rs
+++ b/src/common/mod.rs
@@ -11,6 +11,9 @@ use crate::DecodeHintType;
 use crate::RXingResultPoint;
 use encoding::Encoding;
 
+#[cfg(test)]
+mod StringUtilsTestCase;
+
 /*
  * Copyright (C) 2010 ZXing authors
  *