only:covering current implementation

java_console/io/src/main/java/com/rusefi/io/can/HexUtil.java

@@ -11,7 +11,7 @@ public class HexUtil {
         return hexToBytes(hex);
     }
 
-    private static byte[] hexToBytes(String s) {
+    public static byte[] hexToBytes(String s) {
         return hexToBytes(s, 0);
     }
 

java_console/io/src/test/java/com/rusefi/io/can/HexUtilTest.java

@@ -0,0 +1,24 @@
+package com.rusefi.io.can;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertArrayEquals;
+
+public class HexUtilTest {
+    @Test
+    public void decodeSimple() {
+        byte[] pa = HexUtil.hexToBytes("abcd");
+        assertArrayEquals(new byte[]{(byte) 0xab, (byte) 0xcd}, pa);
+    }
+
+    @Test
+    public void decodeUneven() {
+        byte[] pa = HexUtil.hexToBytes("1abcd");
+        assertArrayEquals(new byte[]{1, (byte) 0xab, (byte) 0xcd}, pa);
+    }
+
+    @Test(expected = NumberFormatException.class)
+    public void unexpected() {
+        HexUtil.hexToBytes("0xff");
+    }
+}