[TASK] Restructure tests/ folder.

Move unit tests to tests/unit/. Get the old still working UnitTests
into a working state again.
Updated composer.json with required-dev packages.
Create a new folder tests/acceptance for Behat functional/acceptance
testing. Add a first Feature draft of a Behat functional test for
local login.

tests/unit/ContainsAttributeTest.php

@@ -0,0 +1,53 @@
+<?php
+/**
+ * this test tests the contains_attribute function
+ *
+ * @package test.util
+ */
+
+use PHPUnit\Framework\TestCase;
+
+/** required, it is the file under test */
+require_once('include/text.php');
+
+/**
+ * TestCase for the contains_attribute function
+ *
+ * @author Alexander Kampmann
+ * @package test.util
+ */
+class ContainsAttributeTest extends TestCase {
+	/**
+	 * test attribute contains
+	 */
+	public function testAttributeContains1() {
+		$testAttr="class1 notclass2 class3";
+		$this->assertTrue(attribute_contains($testAttr, "class3"));
+		$this->assertFalse(attribute_contains($testAttr, "class2"));
+	}
+
+	/**
+	 * test attribute contains
+	 */
+	public function testAttributeContains2() {
+		$testAttr="class1 not-class2 class3";
+		$this->assertTrue(attribute_contains($testAttr, "class3"));
+		$this->assertFalse(attribute_contains($testAttr, "class2"));
+	}
+
+	/**
+	 * test with empty input
+	 */
+	public function testAttributeContainsEmpty() {
+		$testAttr="";
+		$this->assertFalse(attribute_contains($testAttr, "class2"));
+	}
+
+	/**
+	 * test input with special chars
+	 */
+	public function testAttributeContainsSpecialChars() {
+		$testAttr="--... %\$ä() /(=?}";
+		$this->assertFalse(attribute_contains($testAttr, "class2"));
+	}
+}