diff --git a/test/PHPMailer/PHPMailerTest.php b/test/PHPMailer/PHPMailerTest.php
index ffdcc5eb..43af387a 100644
--- a/test/PHPMailer/PHPMailerTest.php
+++ b/test/PHPMailer/PHPMailerTest.php
@@ -16,7 +16,6 @@ namespace PHPMailer\Test\PHPMailer;
 use PHPMailer\PHPMailer\Exception;
 use PHPMailer\PHPMailer\OAuth;
 use PHPMailer\PHPMailer\PHPMailer;
-use PHPMailer\PHPMailer\POP3;
 use PHPMailer\PHPMailer\SMTP;
 use PHPMailer\Test\TestCase;
 
@@ -1857,60 +1856,6 @@ EOT;
         );
     }
 
-    /**
-     * Use a fake POP3 server to test POP-before-SMTP auth with a known-good login.
-     *
-     * @group pop3
-     */
-    public function testPopBeforeSmtpGood()
-    {
-        //Start a fake POP server
-        $pid = shell_exec(
-            '/usr/bin/nohup ' .
-            \PHPMAILER_INCLUDE_DIR .
-            '/test/runfakepopserver.sh 1100 >/dev/null 2>/dev/null & printf "%u" $!'
-        );
-        $this->pids[] = $pid;
-
-        sleep(1);
-        //Test a known-good login
-        self::assertTrue(
-            POP3::popBeforeSmtp('localhost', 1100, 10, 'user', 'test'),
-            'POP before SMTP failed'
-        );
-        //Kill the fake server, don't care if it fails
-        @shell_exec('kill -TERM ' . escapeshellarg($pid));
-        sleep(2);
-    }
-
-    /**
-     * Use a fake POP3 server to test POP-before-SMTP auth
-     * with a known-bad login.
-     *
-     * @group pop3
-     */
-    public function testPopBeforeSmtpBad()
-    {
-        //Start a fake POP server on a different port
-        //so we don't inadvertently connect to the previous instance
-        $pid = shell_exec(
-            '/usr/bin/nohup ' .
-            \PHPMAILER_INCLUDE_DIR .
-            '/test/runfakepopserver.sh 1101 >/dev/null 2>/dev/null & printf "%u" $!'
-        );
-        $this->pids[] = $pid;
-
-        sleep(2);
-        //Test a known-bad login
-        self::assertFalse(
-            POP3::popBeforeSmtp('localhost', 1101, 10, 'user', 'xxx'),
-            'POP before SMTP should have failed'
-        );
-        //Kill the fake server, don't care if it fails
-        @shell_exec('kill -TERM ' . escapeshellarg($pid));
-        sleep(2);
-    }
-
     /**
      * Test SMTP host connections.
      * This test can take a long time, so run it last.
diff --git a/test/POP3/PopBeforeSmtpTest.php b/test/POP3/PopBeforeSmtpTest.php
new file mode 100644
index 00000000..e34b6000
--- /dev/null
+++ b/test/POP3/PopBeforeSmtpTest.php
@@ -0,0 +1,114 @@
+<?php
+
+/**
+ * PHPMailer - PHP email transport unit tests.
+ * PHP version 5.5.
+ *
+ * @author    Marcus Bointon <phpmailer@synchromedia.co.uk>
+ * @author    Andy Prevost
+ * @copyright 2012 - 2020 Marcus Bointon
+ * @copyright 2004 - 2009 Andy Prevost
+ * @license   http://www.gnu.org/copyleft/lesser.html GNU Lesser General Public License
+ */
+
+namespace PHPMailer\Test\POP3;
+
+use PHPMailer\PHPMailer\POP3;
+use Yoast\PHPUnitPolyfills\TestCases\TestCase;
+
+/**
+ * Test Pop before Smtp functionality.
+ *
+ * @group pop3
+ *
+ * @covers PHPMailer\PHPMailer\POP3
+ */
+final class PopBeforeSmtpTest extends TestCase
+{
+
+    /**
+     * PIDs of any processes we need to kill.
+     *
+     * @var array
+     */
+    protected $pids = [];
+
+    /**
+     * Run before each test class.
+     */
+    public static function set_up_before_class()
+    {
+        if (defined('PHPMAILER_INCLUDE_DIR') === false) {
+            /*
+             * Set up default include path.
+             * Default to the dir above the test dir, i.e. the project home dir.
+             */
+            define('PHPMAILER_INCLUDE_DIR', dirname(__DIR__));
+        }
+    }
+
+    /**
+     * Run after each test is completed.
+     */
+    protected function tear_down()
+    {
+        foreach ($this->pids as $pid) {
+            $p = escapeshellarg($pid);
+            shell_exec("ps $p && kill -TERM $p");
+        }
+    }
+
+    /**
+     * Use a fake POP3 server to test POP-before-SMTP auth with a known-good login.
+     */
+    public function testPopBeforeSmtpGood()
+    {
+        // Start a fake POP server.
+        $pid = shell_exec(
+            '/usr/bin/nohup ' .
+            \PHPMAILER_INCLUDE_DIR .
+            '/test/runfakepopserver.sh 1100 >/dev/null 2>/dev/null & printf "%u" $!'
+        );
+        $this->pids[] = $pid;
+
+        sleep(1);
+
+        // Test a known-good login.
+        self::assertTrue(
+            POP3::popBeforeSmtp('localhost', 1100, 10, 'user', 'test'),
+            'POP before SMTP failed'
+        );
+
+        // Kill the fake server, don't care if it fails.
+        @shell_exec('kill -TERM ' . escapeshellarg($pid));
+        sleep(2);
+    }
+
+    /**
+     * Use a fake POP3 server to test POP-before-SMTP auth
+     * with a known-bad login.
+     */
+    public function testPopBeforeSmtpBad()
+    {
+        // Start a fake POP server on a different port,
+        // so we don't inadvertently connect to the previous instance.
+        $pid = shell_exec(
+            '/usr/bin/nohup ' .
+            \PHPMAILER_INCLUDE_DIR .
+            '/test/runfakepopserver.sh 1101 >/dev/null 2>/dev/null & printf "%u" $!'
+        );
+        $this->pids[] = $pid;
+
+        sleep(2);
+
+        // Test a known-bad login.
+        self::assertFalse(
+            POP3::popBeforeSmtp('localhost', 1101, 10, 'user', 'xxx'),
+            'POP before SMTP should have failed'
+        );
+
+        // Kill the fake server, don't care if it fails.
+        @shell_exec('kill -TERM ' . escapeshellarg($pid));
+        sleep(2);
+    }
+}
diff --git a/test/TestCase.php b/test/TestCase.php
index 00161a1b..6f968bca 100644
--- a/test/TestCase.php
+++ b/test/TestCase.php
@@ -50,13 +50,6 @@ abstract class TestCase extends PolyfillTestCase
      */
     private $NoteLog = [];
 
-    /**
-     * PIDs of any processes we need to kill.
-     *
-     * @var array
-     */
-    protected $pids = [];
-
     /**
      * Run before each test class.
      */
@@ -143,11 +136,6 @@ abstract class TestCase extends PolyfillTestCase
         $this->Mail = null;
         $this->ChangeLog = [];
         $this->NoteLog = [];
-
-        foreach ($this->pids as $pid) {
-            $p = escapeshellarg($pid);
-            shell_exec("ps $p && kill -TERM $p");
-        }
     }
 
     /**