Updated StringUtils class and tests

Author: jaaufauvre

src/Developer/Utils/StringUtils.php

@@ -3,6 +3,10 @@
 
 class StringUtils {
 
+    public static function contains($string, $search) {
+        return empty($search) || strpos($string, $search) !== false;
+    }
+
     public static function startsWith($string, $prefix) {
         return empty($prefix) || strrpos($string, $prefix, -strlen($string)) !== false;
     }

tests/Developer/Utils/StringUtilsTest.php

@@ -0,0 +1,28 @@
+<?php
+namespace Mastercard\Developer\Utils;
+
+use PHPUnit\Framework\TestCase;
+
+class StringUtilsTest extends TestCase {
+
+    public function testContains() {
+        $this->assertTrue(StringUtils::contains('Hello', ''));
+        $this->assertTrue(StringUtils::contains('Hello', 'el'));
+        $this->assertFalse(StringUtils::contains('Hello', 'le'));
+        $this->assertFalse(StringUtils::contains('Hello', '-Hello-'));
+    }
+
+    public function testStartWith() {
+        $this->assertTrue(StringUtils::startsWith('Hello', ''));
+        $this->assertTrue(StringUtils::startsWith('Hello', 'He'));
+        $this->assertFalse(StringUtils::startsWith('Hello', 'le'));
+        $this->assertFalse(StringUtils::startsWith('Hello', '-Hello-'));
+    }
+
+    public function testEndWith() {
+        $this->assertTrue(StringUtils::endsWith('Hello', ''));
+        $this->assertTrue(StringUtils::endsWith('Hello', 'lo'));
+        $this->assertFalse(StringUtils::endsWith('Hello', 'le'));
+        $this->assertFalse(StringUtils::endsWith('Hello', '-Hello-'));
+    }
+}