fix incorrect parsing of List/Writable parsing

add unit test to prevent such mistakes from occurring again
fixes #36
fixes #37
fixes #38

src/main/java/org/elasticsearch/hadoop/util/WritableUtils.java

@@ -27,6 +27,7 @@
 import org.apache.hadoop.io.AbstractMapWritable;
 import org.apache.hadoop.io.ArrayWritable;
 import org.apache.hadoop.io.BooleanWritable;
+import org.apache.hadoop.io.ByteWritable;
 import org.apache.hadoop.io.BytesWritable;
 import org.apache.hadoop.io.DoubleWritable;
 import org.apache.hadoop.io.FloatWritable;
@@ -61,6 +62,9 @@ else if (object instanceof Long) {
         else if (object instanceof Integer) {
             return new VIntWritable((Integer) object);
         }
+        else if (object instanceof Byte) {
+            return new ByteWritable((Byte) object);
+        }
         else if (object instanceof Double) {
             return new DoubleWritable((Double) object);
         }
@@ -136,6 +140,9 @@ else if (writable instanceof VLongWritable) {
         else if (writable instanceof VIntWritable) {
             return ((VIntWritable) writable).get();
         }
+        else if (writable instanceof ByteWritable) {
+            return ((ByteWritable) writable).get();
+        }
         else if (writable instanceof DoubleWritable) {
             return ((DoubleWritable) writable).get();
         }
@@ -154,6 +161,7 @@ else if (writable instanceof ArrayWritable) {
             for (Writable wrt : writables) {
                 list.add(fromWritable(wrt));
             }
+            return list;
         }
         else if (writable instanceof AbstractMapWritable) {
             Map<Writable, Writable> smap = (Map) writable;

src/test/java/org/elasticsearch/hadoop/unit/util/WritableUtilsTest.java

@@ -0,0 +1,89 @@
+/*
+ * Copyright 2013 the original author or authors.
+ *
+ * Licensed 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.elasticsearch.hadoop.unit.util;
+
+import java.util.Arrays;
+import java.util.Collections;
+
+import org.elasticsearch.hadoop.util.WritableUtils;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+/**
+ *
+ */
+public class WritableUtilsTest {
+
+    @Test
+    public void testNull() {
+        testToWritableAndBack(null);
+    }
+
+    @Test
+    public void testString() {
+        testToWritableAndBack("some string");
+    }
+
+    @Test
+    public void testLong() {
+        testToWritableAndBack(Long.MAX_VALUE);
+    }
+
+    @Test
+    public void testInteger() {
+        testToWritableAndBack(Integer.MAX_VALUE);
+    }
+
+    @Test
+    public void testDouble() {
+        testToWritableAndBack(Double.MAX_VALUE);
+    }
+
+    @Test
+    public void testFloat() {
+        testToWritableAndBack(Float.MAX_VALUE);
+    }
+
+    @Test
+    public void testBoolean() {
+        testToWritableAndBack(Boolean.TRUE);
+    }
+
+    @Test
+    public void testByte() {
+        testToWritableAndBack(Byte.MAX_VALUE);
+    }
+
+    @Test
+    public void testByteArray() {
+        testToWritableAndBack("byte array".getBytes());
+    }
+
+    @Test
+    public void testList() {
+        testToWritableAndBack(Arrays.asList(new String[] { "one", "two" }));
+    }
+
+    @Test
+    public void testMap() {
+        testToWritableAndBack(Collections.singletonMap("key", "value"));
+    }
+
+    private void testToWritableAndBack(Object obj) {
+        assertEquals(obj, WritableUtils.fromWritable(WritableUtils.toWritable(obj)));
+    }
+}