Add internal function replacement

src/UnixInternalFunctions.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Xepozz\InternalMocker;
+
+class UnixInternalFunctions
+{
+    public static function time(): int
+    {
+        return (int) `date +%s`;
+    }
+}

tests/Integration/UnitInternalFunctionsTest.php

@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Xepozz\InternalMocker\Tests\Integration;
+
+use PHPUnit\Framework\TestCase;
+use Xepozz\InternalMocker\UnixInternalFunctions;
+
+final class UnitInternalFunctionsTest extends TestCase
+{
+    public function testTime()
+    {
+        $this->assertEquals(`date +%s`, UnixInternalFunctions::time());
+    }
+}