Introduce RSA test class

The "@expectedException UnexpectedValueException" was just wrong here.

test/php/library/Icinga/Crypt/RSATest.php

@@ -0,0 +1,49 @@
+<?php
+// Icinga Web 2 | (c) 2020 Icinga Development Team | GPLv2+
+
+namespace Tests\Icinga\Crypt;
+
+use Icinga\Crypt\RSA;
+use Icinga\Test\BaseTestCase;
+use InvalidArgumentException;
+use UnexpectedValueException;
+
+class RSATest extends BaseTestCase
+{
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    function testLoadKeyThrowsExceptionIfMoreThanTwoKeysGiven()
+    {
+        (new RSA())->loadKey('one', 'two', 'three');
+    }
+
+    /**
+     * @expectedException UnexpectedValueException
+     */
+    function testGetPublicKeyThrowsExceptionIfNoPublicKeySet()
+    {
+        (new RSA())->getPublicKey();
+    }
+
+    /**
+     * @expectedException UnexpectedValueException
+     */
+    function testGetPrivateKeyThrowsExceptionIfNoPrivateKeySet()
+    {
+        (new RSA())->getPrivateKey();
+    }
+
+    function testLoadKeyAutomaticallyDetectsThePublicAndPrivateKey()
+    {
+        list($privateKey, $publicKey) = RSA::keygen();
+
+        $rsa = (new RSA())->loadKey($publicKey, $privateKey);
+        $this->assertSame($privateKey, $rsa->getPrivateKey());
+        $this->assertSame($publicKey, $rsa->getPublicKey());
+
+        $rsa = (new RSA())->loadKey($privateKey, $publicKey);
+        $this->assertSame($privateKey, $rsa->getPrivateKey());
+        $this->assertSame($publicKey, $rsa->getPublicKey());
+    }
+}