diff --git a/test/php/library/X509/JobTest.php b/test/php/library/X509/JobTest.php
new file mode 100644
index 00000000..6dbe069c
--- /dev/null
+++ b/test/php/library/X509/JobTest.php
@@ -0,0 +1,53 @@
+<?php
+
+namespace Tests\Icinga\Modules\X509;
+
+use Icinga\Module\X509\Job;
+use PHPUnit\Framework\TestCase;
+
+class JobTest extends TestCase
+{
+    public function testBinaryTransformsHumanReadableIPToItsPaddedVersionCorrectly()
+    {
+        $this->assertSame('0000000000000000000000000ad33720', bin2hex(Job::binary('10.211.55.32')));
+        $this->assertSame(
+            '2a0104a00004210208a951031cba4915',
+            bin2hex(Job::binary('2a01:4a0:4:2102:8a9:5103:1cba:4915'))
+        );
+    }
+
+    public function testIsIPV6()
+    {
+        $this->assertTrue(Job::isIPV6('::1'), 'Job::isIPV6() could not determine valid IP as an IPV6');
+        $this->assertFalse(Job::isIPV6('10.211.54.35'), 'Job::isIPV6() could determines IPV4 as an IPV6');
+    }
+
+    public function testAddrToNumberUndViceVersa()
+    {
+        $this->assertEquals('10.211.55.32', Job::numberToAddr(Job::addrToNumber('10.211.55.32'), false));
+
+        $this->assertEquals('::1', Job::numberToAddr(Job::addrToNumber('::1')));
+        $this->assertEquals(
+            '2a01:4a0:4:2102:8a9:5103:1cba:4915',
+            Job::numberToAddr(Job::addrToNumber('2a01:4a0:4:2102:8a9:5103:1cba:4915'))
+        );
+    }
+
+    public function testIsAddrInsideCidr()
+    {
+        $this->assertTrue(Job::isAddrInside(gmp_import(Job::binary('10.211.55.31')), '10.211.55.30', 24));
+        $this->assertFalse(Job::isAddrInside(Job::addrToNumber('10.211.54.35'), '10.211.55.30', 24));
+
+        $this->assertTrue(
+            Job::isAddrInside(Job::addrToNumber('2001:db8:abcd:0012::1'), '2001:db8:abcd:0012::', 64)
+        );
+        $this->assertTrue(
+            Job::isAddrInside(Job::addrToNumber('2001:db8:abcd:0012:ffff::1'), '2001:db8:abcd:0012::', 64)
+        );
+
+        $this->assertFalse(Job::isAddrInside(Job::addrToNumber('2001:db8:abcd::1'), '2001:db8:abcd:0012::', 64));
+        $this->assertFalse(
+            Job::isAddrInside(Job::addrToNumber('2001:db8:abcd:0011::'), '2001:db8:abcd:0012::', 64)
+        );
+    }
+}