diff --git a/library/build.gradle b/library/build.gradle
index 3e5778d..b45ddfb 100644
--- a/library/build.gradle
+++ b/library/build.gradle
@@ -30,5 +30,7 @@ android {
 }
 
 dependencies {
+    testCompile 'junit:junit:4.12'
+    testCompile "org.mockito:mockito-core:1.9.5"
     compile fileTree(include: ['*.jar'], dir: 'libs')
 }
diff --git a/library/library.iml b/library/library.iml
index 380a1e3..f457fe4 100644
--- a/library/library.iml
+++ b/library/library.iml
@@ -9,13 +9,12 @@
     <facet type="android" name="Android">
       <configuration>
         <option name="SELECTED_BUILD_VARIANT" value="debug" />
-        <option name="SELECTED_TEST_ARTIFACT" value="_android_test_" />
+        <option name="SELECTED_TEST_ARTIFACT" value="_unit_test_" />
         <option name="ASSEMBLE_TASK_NAME" value="assembleDebug" />
         <option name="COMPILE_JAVA_TASK_NAME" value="compileDebugSources" />
         <option name="SOURCE_GEN_TASK_NAME" value="generateDebugSources" />
-        <option name="ASSEMBLE_TEST_TASK_NAME" value="assembleDebugAndroidTest" />
-        <option name="COMPILE_JAVA_TEST_TASK_NAME" value="compileDebugAndroidTestSources" />
-        <option name="TEST_SOURCE_GEN_TASK_NAME" value="generateDebugAndroidTestSources" />
+        <option name="ASSEMBLE_TEST_TASK_NAME" value="assembleDebugUnitTest" />
+        <option name="COMPILE_JAVA_TEST_TASK_NAME" value="compileDebugUnitTestSources" />
         <option name="ALLOW_USER_CONFIGURATION" value="false" />
         <option name="MANIFEST_FILE_RELATIVE_PATH" value="/src/main/AndroidManifest.xml" />
         <option name="RES_FOLDER_RELATIVE_PATH" value="/src/main/res" />
@@ -27,7 +26,7 @@
   </component>
   <component name="NewModuleRootManager" inherit-compiler-output="false">
     <output url="file://$MODULE_DIR$/build/intermediates/classes/debug" />
-    <output-test url="file://$MODULE_DIR$/build/intermediates/classes/androidTest/debug" />
+    <output-test url="file://$MODULE_DIR$/build/intermediates/classes/test/debug" />
     <exclude-output />
     <content url="file://$MODULE_DIR$">
       <sourceFolder url="file://$MODULE_DIR$/build/generated/source/r/debug" isTestSource="false" generated="true" />
@@ -36,12 +35,6 @@
       <sourceFolder url="file://$MODULE_DIR$/build/generated/source/rs/debug" isTestSource="false" generated="true" />
       <sourceFolder url="file://$MODULE_DIR$/build/generated/res/rs/debug" type="java-resource" />
       <sourceFolder url="file://$MODULE_DIR$/build/generated/res/generated/debug" type="java-resource" />
-      <sourceFolder url="file://$MODULE_DIR$/build/generated/source/r/androidTest/debug" isTestSource="true" generated="true" />
-      <sourceFolder url="file://$MODULE_DIR$/build/generated/source/aidl/androidTest/debug" isTestSource="true" generated="true" />
-      <sourceFolder url="file://$MODULE_DIR$/build/generated/source/buildConfig/androidTest/debug" isTestSource="true" generated="true" />
-      <sourceFolder url="file://$MODULE_DIR$/build/generated/source/rs/androidTest/debug" isTestSource="true" generated="true" />
-      <sourceFolder url="file://$MODULE_DIR$/build/generated/res/rs/androidTest/debug" type="java-test-resource" />
-      <sourceFolder url="file://$MODULE_DIR$/build/generated/res/generated/androidTest/debug" type="java-test-resource" />
       <sourceFolder url="file://$MODULE_DIR$/src/debug/res" type="java-resource" />
       <sourceFolder url="file://$MODULE_DIR$/src/debug/resources" type="java-resource" />
       <sourceFolder url="file://$MODULE_DIR$/src/debug/assets" type="java-resource" />
@@ -49,6 +42,13 @@
       <sourceFolder url="file://$MODULE_DIR$/src/debug/java" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/src/debug/jni" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/src/debug/rs" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/src/testDebug/res" type="java-test-resource" />
+      <sourceFolder url="file://$MODULE_DIR$/src/testDebug/resources" type="java-test-resource" />
+      <sourceFolder url="file://$MODULE_DIR$/src/testDebug/assets" type="java-test-resource" />
+      <sourceFolder url="file://$MODULE_DIR$/src/testDebug/aidl" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/src/testDebug/java" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/src/testDebug/jni" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/src/testDebug/rs" isTestSource="true" />
       <sourceFolder url="file://$MODULE_DIR$/src/main/res" type="java-resource" />
       <sourceFolder url="file://$MODULE_DIR$/src/main/resources" type="java-resource" />
       <sourceFolder url="file://$MODULE_DIR$/src/main/assets" type="java-resource" />
@@ -56,13 +56,13 @@
       <sourceFolder url="file://$MODULE_DIR$/src/main/java" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/src/main/jni" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/src/main/rs" isTestSource="false" />
-      <sourceFolder url="file://$MODULE_DIR$/src/androidTest/res" type="java-test-resource" />
-      <sourceFolder url="file://$MODULE_DIR$/src/androidTest/resources" type="java-test-resource" />
-      <sourceFolder url="file://$MODULE_DIR$/src/androidTest/assets" type="java-test-resource" />
-      <sourceFolder url="file://$MODULE_DIR$/src/androidTest/aidl" isTestSource="true" />
-      <sourceFolder url="file://$MODULE_DIR$/src/androidTest/java" isTestSource="true" />
-      <sourceFolder url="file://$MODULE_DIR$/src/androidTest/jni" isTestSource="true" />
-      <sourceFolder url="file://$MODULE_DIR$/src/androidTest/rs" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/src/test/res" type="java-test-resource" />
+      <sourceFolder url="file://$MODULE_DIR$/src/test/resources" type="java-test-resource" />
+      <sourceFolder url="file://$MODULE_DIR$/src/test/assets" type="java-test-resource" />
+      <sourceFolder url="file://$MODULE_DIR$/src/test/aidl" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/src/test/java" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/src/test/jni" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/src/test/rs" isTestSource="true" />
       <excludeFolder url="file://$MODULE_DIR$/build/intermediates/assets" />
       <excludeFolder url="file://$MODULE_DIR$/build/intermediates/bundles" />
       <excludeFolder url="file://$MODULE_DIR$/build/intermediates/classes" />
@@ -87,5 +87,10 @@
     </content>
     <orderEntry type="jdk" jdkName="Android API 18 Platform" jdkType="Android SDK" />
     <orderEntry type="sourceFolder" forTests="false" />
+    <orderEntry type="library" exported="" scope="TEST" name="objenesis-1.0" level="project" />
+    <orderEntry type="library" exported="" scope="TEST" name="hamcrest-core-1.3" level="project" />
+    <orderEntry type="library" exported="" scope="TEST" name="junit-4.12" level="project" />
+    <orderEntry type="library" exported="" scope="TEST" name="mockable-android-18" level="project" />
+    <orderEntry type="library" exported="" scope="TEST" name="mockito-core-1.9.5" level="project" />
   </component>
 </module>
\ No newline at end of file
diff --git a/library/src/main/java/uk/co/alt236/bluetoothlelib/device/mfdata/IBeaconManufacturerData.java b/library/src/main/java/uk/co/alt236/bluetoothlelib/device/mfdata/IBeaconManufacturerData.java
index 5ec218d..fe338cd 100644
--- a/library/src/main/java/uk/co/alt236/bluetoothlelib/device/mfdata/IBeaconManufacturerData.java
+++ b/library/src/main/java/uk/co/alt236/bluetoothlelib/device/mfdata/IBeaconManufacturerData.java
@@ -65,8 +65,10 @@ public final class IBeaconManufacturerData {
     public IBeaconManufacturerData(final byte[] data) {
         mData = data;
 
-        mCompanyIdentidier = ByteUtils.getIntFrom2ByteArray(
-                ByteUtils.invertArray(Arrays.copyOfRange(mData, 0, 2)));
+        final byte[] intArray = Arrays.copyOfRange(mData, 0, 2);
+        ByteUtils.invertArray(intArray);
+
+        mCompanyIdentidier = ByteUtils.getIntFrom2ByteArray(intArray);
 
         mIBeaconAdvertisment = ByteUtils.getIntFrom2ByteArray(Arrays.copyOfRange(mData, 2, 4));
         mUUID = calculateUUIDString(Arrays.copyOfRange(mData, 4, 20));
diff --git a/library/src/main/java/uk/co/alt236/bluetoothlelib/util/ByteUtils.java b/library/src/main/java/uk/co/alt236/bluetoothlelib/util/ByteUtils.java
index c87de11..2ec67cf 100644
--- a/library/src/main/java/uk/co/alt236/bluetoothlelib/util/ByteUtils.java
+++ b/library/src/main/java/uk/co/alt236/bluetoothlelib/util/ByteUtils.java
@@ -36,7 +36,7 @@ public class ByteUtils {
     }
 
     /**
-     * Checks to see if a byte arry starts with another byte array.
+     * Checks to see if a byte array starts with another byte array.
      *
      * @param array  the array
      * @param prefix the prefix
@@ -78,7 +78,7 @@ public class ByteUtils {
      * <p/>
      * For example, FF will be converted to 255 and not -1.
      *
-     * @param bite the bite
+     * @param bite the byte
      * @return the int from byte
      */
     public static int getIntFromByte(final byte bite) {
@@ -107,12 +107,11 @@ public class ByteUtils {
 
 
     /**
-     * Inverts an array
+     * Inverts an byte array in place.
      *
      * @param array the array
-     * @return the byte[]
      */
-    public static byte[] invertArray(final byte[] array) {
+    public static void invertArray(final byte[] array) {
         final int size = array.length;
         byte temp;
 
@@ -121,7 +120,5 @@ public class ByteUtils {
             array[i] = array[size - 1 - i];
             array[size - 1 - i] = temp;
         }
-
-        return array;
     }
 }
diff --git a/library/src/test/java/uk/co/alt236/bluetoothlelib/util/ByteUtilsTest.java b/library/src/test/java/uk/co/alt236/bluetoothlelib/util/ByteUtilsTest.java
new file mode 100644
index 0000000..d0b5592
--- /dev/null
+++ b/library/src/test/java/uk/co/alt236/bluetoothlelib/util/ByteUtilsTest.java
@@ -0,0 +1,60 @@
+package uk.co.alt236.bluetoothlelib.util;
+
+import junit.framework.TestCase;
+
+/**
+ *
+ */
+public class ByteUtilsTest extends TestCase {
+
+    public void testInvertArray() throws Exception {
+        final byte[] original = {1, 2 ,3 ,4};
+        final byte[] out = new byte[original.length];
+
+        System.arraycopy( original, 0, out, 0, original.length);
+        ByteUtils.invertArray(out);
+
+        assertEquals(original[0], out[3]);
+        assertEquals(original[1], out[2]);
+        assertEquals(original[2], out[1]);
+        assertEquals(original[3], out[0]);
+    }
+
+    public void testGetIntFromByte() throws Exception {
+        byte bite = 127;
+        int integer = ByteUtils.getIntFromByte(bite);
+        assertEquals(127, integer);
+
+        bite = -1;
+        integer = ByteUtils.getIntFromByte(bite);
+        assertEquals(255, integer);
+    }
+
+    public void testDoesArrayBeginWith() throws Exception {
+
+        // If the prefix is longer than the array,
+        // we automatically fail
+        byte[] array = new byte[10];
+        byte[] prefix = new byte[array.length * 2];
+        assertFalse(ByteUtils.doesArrayBeginWith(array, prefix));
+
+        array = new byte[]{1, 2, 3};
+        prefix = new byte[]{1, 3};
+        assertFalse(ByteUtils.doesArrayBeginWith(array, prefix));
+
+        array = new byte[10];
+        prefix = new byte[array.length];
+        assertTrue(ByteUtils.doesArrayBeginWith(array, prefix));
+
+        array = new byte[]{1, 2, 3};
+        prefix = new byte[]{1, 2};
+        assertTrue(ByteUtils.doesArrayBeginWith(array, prefix));
+    }
+
+    public void testByteArrayToHexString() throws Exception {
+        assertEquals("[]", ByteUtils.byteArrayToHexString(new byte[0]));
+
+        final byte[] one = {1, 10, 15, 127};
+        assertEquals("[01, 0A, 0F, 7F]", ByteUtils.byteArrayToHexString(one));
+    }
+}
\ No newline at end of file
diff --git a/sample_app/sample_app.iml b/sample_app/sample_app.iml
index 9610873..0282668 100644
--- a/sample_app/sample_app.iml
+++ b/sample_app/sample_app.iml
@@ -9,13 +9,12 @@
     <facet type="android" name="Android">
       <configuration>
         <option name="SELECTED_BUILD_VARIANT" value="debug" />
-        <option name="SELECTED_TEST_ARTIFACT" value="_android_test_" />
+        <option name="SELECTED_TEST_ARTIFACT" value="_unit_test_" />
         <option name="ASSEMBLE_TASK_NAME" value="assembleDebug" />
         <option name="COMPILE_JAVA_TASK_NAME" value="compileDebugSources" />
         <option name="SOURCE_GEN_TASK_NAME" value="generateDebugSources" />
-        <option name="ASSEMBLE_TEST_TASK_NAME" value="assembleDebugAndroidTest" />
-        <option name="COMPILE_JAVA_TEST_TASK_NAME" value="compileDebugAndroidTestSources" />
-        <option name="TEST_SOURCE_GEN_TASK_NAME" value="generateDebugAndroidTestSources" />
+        <option name="ASSEMBLE_TEST_TASK_NAME" value="assembleDebugUnitTest" />
+        <option name="COMPILE_JAVA_TEST_TASK_NAME" value="compileDebugUnitTestSources" />
         <option name="ALLOW_USER_CONFIGURATION" value="false" />
         <option name="MANIFEST_FILE_RELATIVE_PATH" value="/src/main/AndroidManifest.xml" />
         <option name="RES_FOLDER_RELATIVE_PATH" value="/src/main/res" />
@@ -26,7 +25,7 @@
   </component>
   <component name="NewModuleRootManager" inherit-compiler-output="false">
     <output url="file://$MODULE_DIR$/build/intermediates/classes/debug" />
-    <output-test url="file://$MODULE_DIR$/build/intermediates/classes/androidTest/debug" />
+    <output-test url="file://$MODULE_DIR$/build/intermediates/classes/test/debug" />
     <exclude-output />
     <content url="file://$MODULE_DIR$">
       <sourceFolder url="file://$MODULE_DIR$/build/generated/source/r/debug" isTestSource="false" generated="true" />
@@ -35,12 +34,6 @@
       <sourceFolder url="file://$MODULE_DIR$/build/generated/source/rs/debug" isTestSource="false" generated="true" />
       <sourceFolder url="file://$MODULE_DIR$/build/generated/res/rs/debug" type="java-resource" />
       <sourceFolder url="file://$MODULE_DIR$/build/generated/res/generated/debug" type="java-resource" />
-      <sourceFolder url="file://$MODULE_DIR$/build/generated/source/r/androidTest/debug" isTestSource="true" generated="true" />
-      <sourceFolder url="file://$MODULE_DIR$/build/generated/source/aidl/androidTest/debug" isTestSource="true" generated="true" />
-      <sourceFolder url="file://$MODULE_DIR$/build/generated/source/buildConfig/androidTest/debug" isTestSource="true" generated="true" />
-      <sourceFolder url="file://$MODULE_DIR$/build/generated/source/rs/androidTest/debug" isTestSource="true" generated="true" />
-      <sourceFolder url="file://$MODULE_DIR$/build/generated/res/rs/androidTest/debug" type="java-test-resource" />
-      <sourceFolder url="file://$MODULE_DIR$/build/generated/res/generated/androidTest/debug" type="java-test-resource" />
       <sourceFolder url="file://$MODULE_DIR$/src/debug/res" type="java-resource" />
       <sourceFolder url="file://$MODULE_DIR$/src/debug/resources" type="java-resource" />
       <sourceFolder url="file://$MODULE_DIR$/src/debug/assets" type="java-resource" />
@@ -48,6 +41,13 @@
       <sourceFolder url="file://$MODULE_DIR$/src/debug/java" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/src/debug/jni" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/src/debug/rs" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/src/testDebug/res" type="java-test-resource" />
+      <sourceFolder url="file://$MODULE_DIR$/src/testDebug/resources" type="java-test-resource" />
+      <sourceFolder url="file://$MODULE_DIR$/src/testDebug/assets" type="java-test-resource" />
+      <sourceFolder url="file://$MODULE_DIR$/src/testDebug/aidl" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/src/testDebug/java" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/src/testDebug/jni" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/src/testDebug/rs" isTestSource="true" />
       <sourceFolder url="file://$MODULE_DIR$/src/main/res" type="java-resource" />
       <sourceFolder url="file://$MODULE_DIR$/src/main/resources" type="java-resource" />
       <sourceFolder url="file://$MODULE_DIR$/src/main/assets" type="java-resource" />
@@ -55,13 +55,13 @@
       <sourceFolder url="file://$MODULE_DIR$/src/main/java" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/src/main/jni" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/src/main/rs" isTestSource="false" />
-      <sourceFolder url="file://$MODULE_DIR$/src/androidTest/res" type="java-test-resource" />
-      <sourceFolder url="file://$MODULE_DIR$/src/androidTest/resources" type="java-test-resource" />
-      <sourceFolder url="file://$MODULE_DIR$/src/androidTest/assets" type="java-test-resource" />
-      <sourceFolder url="file://$MODULE_DIR$/src/androidTest/aidl" isTestSource="true" />
-      <sourceFolder url="file://$MODULE_DIR$/src/androidTest/java" isTestSource="true" />
-      <sourceFolder url="file://$MODULE_DIR$/src/androidTest/jni" isTestSource="true" />
-      <sourceFolder url="file://$MODULE_DIR$/src/androidTest/rs" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/src/test/res" type="java-test-resource" />
+      <sourceFolder url="file://$MODULE_DIR$/src/test/resources" type="java-test-resource" />
+      <sourceFolder url="file://$MODULE_DIR$/src/test/assets" type="java-test-resource" />
+      <sourceFolder url="file://$MODULE_DIR$/src/test/aidl" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/src/test/java" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/src/test/jni" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/src/test/rs" isTestSource="true" />
       <excludeFolder url="file://$MODULE_DIR$/build/intermediates/assets" />
       <excludeFolder url="file://$MODULE_DIR$/build/intermediates/bundles" />
       <excludeFolder url="file://$MODULE_DIR$/build/intermediates/classes" />
@@ -90,6 +90,7 @@
     <orderEntry type="library" exported="" name="android-support-v4" level="project" />
     <orderEntry type="library" exported="" name="sacklist-1.0.0" level="project" />
     <orderEntry type="library" exported="" name="EasyCursor-0.1.1" level="project" />
+    <orderEntry type="library" exported="" scope="TEST" name="mockable-android-18" level="project" />
     <orderEntry type="library" exported="" name="butterknife-4.0.1" level="project" />
     <orderEntry type="module" module-name="library" exported="" />
   </component>