diff --git a/.gitignore b/.gitignore
index 0aa35273..2a9aa49c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,3 +15,4 @@ plugins/additional_plugins*
 .DS_Store
 .editorconfig
 *.git
+tests/phpunit.xml
diff --git a/include/functions.inc.php b/include/functions.inc.php
index 2dc4d148..c8e305a9 100644
--- a/include/functions.inc.php
+++ b/include/functions.inc.php
@@ -62,7 +62,7 @@ function serendipity_gzCompression() {
 function serendipity_serverOffsetHour($timestamp = null, $negative = false) {
     global $serendipity;
 
-    if ($timestamp == null) {
+    if ($timestamp === null) {
         $timestamp = time();
     }
 
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
new file mode 100644
index 00000000..e2c68f86
--- /dev/null
+++ b/tests/bootstrap.php
@@ -0,0 +1,2 @@
+<?php
+define('S9Y_INCLUDE_PATH', dirname(__FILE__) . '/../');
diff --git a/tests/include/functionsTest.php b/tests/include/functionsTest.php
new file mode 100644
index 00000000..fd49b718
--- /dev/null
+++ b/tests/include/functionsTest.php
@@ -0,0 +1,73 @@
+<?php
+
+$serendipity['dbType'] = 'pdo-sqlite';
+require_once dirname(__FILE__) . '/../../include/functions.inc.php';
+
+/**
+ * Class functionsTest
+ */
+class functionsTest extends PHPUnit_Framework_TestCase
+{
+    /**
+     * @test
+     * @dataProvider serverOffsetHourDataProvider
+     */
+    public function test_serendipity_serverOffsetHour($serverOffsetHours, $timestamp, $negative, $expected)
+    {
+        global $serendipity;
+        $serendipity['serverOffsetHours'] = $serverOffsetHours;
+        $result = serendipity_serverOffsetHour($timestamp, $negative);
+        $this->assertEquals($expected, $result);
+    }
+
+    /**
+     * @return array
+     */
+    public function serverOffsetHourDataProvider()
+    {
+        return array(
+            array(0, 0, false, 0),
+            array(0, 0, true, 0),
+            array(0, 960793800, false, 960793800),
+            array(0, 960793800, true, 960793800),
+            array(10, 0, false, 36000),
+            array(10, 0, true, -36000),
+            array(10, 960793800, false, 960829800),
+            array(10, 960793800, true, 960757800),
+        );
+    }
+
+    /**
+     * @test
+     * @dataProvider serverOffsetHourWithTimestampNullDataProvider
+     */
+    public function test_serendipity_serverOffsetHourWithTimestampNull($serverOffsetHours, $negative)
+    {
+        global $serendipity;
+        $now = time();
+        $serendipity['serverOffsetHours'] = $serverOffsetHours;
+        $result = serendipity_serverOffsetHour(null, $negative);
+        if ($serverOffsetHours > 0) {
+            if ($negative) {
+                $this->assertGreaterThanOrEqual($now - ($serverOffsetHours * 3600), $result);
+            } else {
+                $this->assertGreaterThan($now - ($serverOffsetHours * 3600), $result);
+            }
+        } else {
+            $this->assertGreaterThanOrEqual($now, $result);
+        }
+    }
+
+    /**
+     * @return array
+     */
+    public function serverOffsetHourWithTimestampNullDataProvider()
+    {
+        return array(
+            array(null, false),
+            array(null, true),
+            array(10, false),
+            array(10, true),
+        );
+    }
+}
diff --git a/tests/phpunit.xml.dist b/tests/phpunit.xml.dist
new file mode 100644
index 00000000..ad28e69d
--- /dev/null
+++ b/tests/phpunit.xml.dist
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<phpunit bootstrap="bootstrap.php"
+         backupGlobals="true"
+         convertErrorsToExceptions="true"
+         convertNoticesToExceptions="true"
+         convertWarningsToExceptions="true"
+         colors="true">
+    <php>
+        <const name="IN_serendipity" value="true"/>
+        <!--<const name="IS_installed" value="true"/>-->
+        <!--<const name="USERLEVEL_ADMIN" value="255"/>-->
+        <!--<const name="USERLEVEL_CHIEF" value="1"/>-->
+        <!--<const name="USERLEVEL_EDITOR" value="0"/>-->
+        <!--<const name="DB_DSN" value="sqlite:dbname=s9y_test;host=localhost" />-->
+        <!--<const name="DB_HOST" value="localhost" />-->
+        <!--<const name="DB_TYPE" value="pdo-sqlite" />-->
+        <!--<const name="DB_USER" value="s9y_test" />-->
+        <!--<const name="DB_PASSWD" value="s9y_test" />-->
+        <!--<const name="DB_DBNAME" value="s9y_test" />-->
+        <!--<const name="TEST_DB" value="test.db" />-->
+        <!--<const name="PATH_SMARTY_COMPILE" value="templates_c" />-->
+    </php>
+    <testsuites>
+        <testsuite name="include">
+            <directory>../tests/include</directory>
+        </testsuite>
+    </testsuites>
+</phpunit>