diff --git a/tests/classes/StringTest.php b/tests/classes/StringTest.php
index c9fdf8d..c3308ea 100644
--- a/tests/classes/StringTest.php
+++ b/tests/classes/StringTest.php
@@ -4,13 +4,108 @@ require_once 'classes/String.php';
 
 class StringTest extends PHPUnit_Framework_TestCase
 {
-	public function testUpperWords()
+	/**
+	 * @dataProvider providerFormatPhoneNumber
+	 */
+	public function testFormatPhoneNumber($a, $b)
 	{
-		$this->assertEquals(String::upperWords('foo@bar.com'), 'foo@bar.com');
-		$this->assertEquals(String::upperWords('FOO@BAR.COM'), 'FOO@BAR.COM');
-		$this->assertEquals(String::upperWords('foo bar'),     'Foo Bar');
-		$this->assertEquals(String::upperWords('FOO BAR'),     'Foo Bar');
-		$this->assertEquals(String::upperWords('fOO bAR'),     'Foo Bar');
+		$this->assertEquals(String::formatPhoneNumber($a), $b);
+	}
+
+	public function providerFormatPhoneNumber()
+	{
+		return array(
+			array('1234567890',            '123-456-7890'),
+			array('123 456 7890',          '123-456-7890'),
+			array('123.456.7890',          '123-456-7890'),
+			array('123_456_7890',          '123-456-7890'),
+			array('1234567890',            '123-456-7890'),
+			array('1234-56-7890',          '123-456-7890'),
+			array('(123) 456-7890',        '123-456-7890'),
+			array('1234567890 x1000',      '123-456-7890x1000'),
+			array('(123) 456-7890_x10.00', '123-456-7890x1000'),
+		);
+	}
+
+	/**
+	 * @dataProvider providerGenerateGravatarHash
+	 */
+	public function testGenerateGravatarHash($a, $b)
+	{
+		$this->assertEquals(String::generateGravatarHash($a), $b);
+	}
+
+	public function providerGenerateGravatarHash()
+	{
+		return array(
+			array('foo@bar.com', 'f3ada405ce890b6f8204094deb12d8a8'),
+			array('FOO@BAR.COM', 'f3ada405ce890b6f8204094deb12d8a8'),
+		);
+	}
+
+	public function testIsEmpty()
+	{
+		$this->assertTrue(String::isEmpty(''));
+		$this->assertTrue(String::isEmpty(' '));
+		$this->assertTrue(String::isEmpty(false));
+		$this->assertTrue(String::isEmpty(null));
+		$this->assertTrue(String::isEmpty(true, false));
+
+		$this->assertFalse(String::isEmpty(0));
+		$this->assertFalse(String::isEmpty('foo'));
+		$this->assertFalse(String::isEmpty(' bar '));
+		$this->assertFalse(String::isEmpty(true));
+	}
+
+	public function testRandom()
+	{
+		$this->assertEquals(strlen(String::random()),   8);
+		$this->assertEquals(strlen(String::random(16)), 16);
+
+		$this->assertEquals(preg_match('/[A-Z0-9]/', String::random(32, true,  true)),  1);
+		$this->assertEquals(preg_match('/[A-Z]/',    String::random(32, true,  false)), 1);
+		$this->assertEquals(preg_match('/[0-9]/',    String::random(32, false, true)),  1);
+
+		$this->assertEquals(preg_match('/[0-9]/',    String::random(32, true,  false)), 0);
+		$this->assertEquals(preg_match('/[A-Z]/',    String::random(32, false, true)),  0);
+		$this->assertEquals(preg_match('/[A-Z0-9]/', String::random(32, false, false)), 0);
+	}
+
+	/**
+	 * @dataProvider providerTruncate
+	 */
+	public function testTruncate($a, $b, $c, $d)
+	{
+		$this->assertEquals(String::truncate($a, $b, $c), $d);
+	}
+
+	public function providerTruncate()
+	{
+		return array(
+			array('foo bar', 3, true,  '<span title="foo bar" style="cursor:help">foo...</span>'),
+			array('foo bar', 3, false, 'foo...'),
+			array('foo bar', 7, true,  'foo bar'),
+			array('foo bar', 8, true,  'foo bar'),
+		);
+	}
+
+	/**
+	 * @dataProvider providerUpperWords
+	 */
+	public function testUpperWords($a, $b)
+	{
+		$this->assertEquals(String::upperWords($a), $b);
+	}
+
+	public function providerUpperWords()
+	{
+		return array(
+			array('foo bar',     'Foo Bar'),
+			array('FOO BAR',     'Foo Bar'),
+			array('fOO bAR',     'Foo Bar'),
+			array('foo@bar.com', 'foo@bar.com'),
+			array('FOO@BAR.COM', 'FOO@BAR.COM'),
+		);
 	}
 }