added language tests.

tests/Cases/LangTest.php

+<?php use Laravel\Lang;
+
+class LangTest extends PHPUnit_Framework_TestCase {
+
+	public function test_simple_language_lines_can_be_retrieved()
+	{
+		$language = require LANG_PATH.'en/validation.php';
+
+		$this->assertEquals($language['required'], Lang::line('validation.required')->get());
+	}
+
+	public function test_default_value_is_returned_when_line_doesnt_exist()
+	{
+		$language = require LANG_PATH.'en/validation.php';
+
+		$this->assertEquals('Taylor', Lang::line('validation.something')->get(null, 'Taylor'));
+	}
+
+	public function test_replacements_can_be_made_on_language_lines()
+	{
+		$language = require LANG_PATH.'en/validation.php';
+
+		$expect = str_replace(':attribute', 'E-Mail', $language['required']);
+
+		$this->assertEquals($expect, Lang::line('validation.required', array('attribute' => 'E-Mail'))->get());
+	}
+
+}
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