Test the Conversion class (#1155)

* add tests for Conversion

* nHexs --> nHex

src/main/java/org/apache/commons/lang3/Conversion.java

@@ -777,7 +777,7 @@ public class Conversion {
     }
 
     /**
-     * Converts an array of Char into a byte using the default (little-endian, Lsb0) byte and
+     * Converts a hexadecimal string into a byte using the default (little-endian, Lsb0) byte and
      * bit ordering.
      *
      * @param src the hexadecimal string to convert
@@ -787,7 +787,7 @@ public class Conversion {
      * @param dstPos the position of the lsb, in bits, in the result byte
      * @param nHex the number of Chars to convert
      * @return a byte containing the selected bits
-     * @throws IllegalArgumentException if {@code (nHexs-1)*4+dstPos >= 8}
+     * @throws IllegalArgumentException if {@code (nHex-1)*4+dstPos >= 8}
      */
     public static byte hexToByte(final String src, final int srcPos, final byte dstInit, final int dstPos,
             final int nHex) {
@@ -795,7 +795,7 @@ public class Conversion {
             return dstInit;
         }
         if ((nHex - 1) * 4 + dstPos >= 8) {
-            throw new IllegalArgumentException("(nHexs-1)*4+dstPos is greater or equal to than 8");
+            throw new IllegalArgumentException("(nHex-1)*4+dstPos is greater than or equal to 8");
         }
         byte out = dstInit;
         for (int i = 0; i < nHex; i++) {

src/test/java/org/apache/commons/lang3/builder/ConversionTest.java

@@ -0,0 +1,43 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.lang3.builder;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.apache.commons.lang3.Conversion;
+import org.junit.jupiter.api.Test;
+
+class ConversionTest {
+
+    @Test
+    void testHexToByte() {
+        assertEquals((byte) 0, Conversion.hexToByte("00", 0, (byte) 0, 0, 0));
+        assertEquals((byte) 0, Conversion.hexToByte("00", 0, (byte) 0, 0, 2));
+    }
+
+    @Test
+    void testHexToByte_nullString() {
+        assertThrows(NullPointerException.class, () -> Conversion.hexToByte(null, 0, (byte) 0, 0, 2));
+    }
+
+    @Test
+    void testHexToByte_IllegalArgument() {
+        assertThrows(IllegalArgumentException.class, () -> Conversion.hexToByte("A0", 0, (byte) 0, 4, 2));
+    }
+
+}