diff --git a/.gitignore b/.gitignore
index 4c51f4d0..6d6b9316 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
+.phpunit.result.cache
 /clover.xml
 /composer.lock
 /coveralls-upload.json
diff --git a/.travis.yml b/.travis.yml
index 8509c812..311d3039 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -12,26 +12,28 @@ env:
 matrix:
   fast_finish: true
   include:
-    - php: 7.1
+    - php: 7.3
       env:
         - DEPS=lowest
-    - php: 7.1
+    - php: 7.3
       env:
         - DEPS=latest
-        - CS_CHECK=true
-        - TEST_COVERAGE=true
-    - php: 7.2
+    - php: 7.4
       env:
         - DEPS=lowest
-    - php: 7.2
+    - php: 7.4
       env:
         - DEPS=latest
-    - php: 7.3
+        - CS_CHECK=true
+        - TEST_COVERAGE=true
+    - php: 8.0
       env:
-        - DEPS=latest
-    - php: 7.4
+        - DEPS=lowest
+        - COMPOSER_ARGS="--no-interaction --ignore-platform-reqs"
+    - php: 8.0
       env:
         - DEPS=latest
+        - COMPOSER_ARGS="--no-interaction --ignore-platform-reqs"
 
 before_install:
   - if [[ $TEST_COVERAGE != 'true' ]]; then phpenv config-rm xdebug.ini || return 0 ; fi
diff --git a/composer.json b/composer.json
index d43eba1e..aa5ded6f 100644
--- a/composer.json
+++ b/composer.json
@@ -25,7 +25,7 @@
         }
     },
     "require": {
-        "php": "^7.1",
+        "php": "^7.3 || ~8.0.0",
         "ext-iconv": "*",
         "laminas/laminas-loader": "^2.5",
         "laminas/laminas-mime": "^2.5",
@@ -36,10 +36,10 @@
     },
     "require-dev": {
         "laminas/laminas-coding-standard": "~1.0.0",
-        "laminas/laminas-config": "^2.6",
+        "laminas/laminas-config": "^3.4",
         "laminas/laminas-crypt": "^2.6 || ^3.0",
         "laminas/laminas-servicemanager": "^3.2.1",
-        "phpunit/phpunit": "^7.5.20"
+        "phpunit/phpunit": "^9.3"
     },
     "suggest": {
         "laminas/laminas-crypt": "Crammd5 support in SMTP Auth",
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 4d03446c..7bf32933 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:noNamespaceSchemaLocation="./vendor/phpunit/phpunit/phpunit.xsd"
+         xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
          bootstrap="./vendor/autoload.php"
          colors="true">
     <testsuites>
@@ -15,11 +15,11 @@
         </exclude>
     </groups>
 
-    <filter>
-        <whitelist addUncoveredFilesFromWhitelist="true">
+    <coverage includeUncoveredFiles="true">
+        <include>
             <directory suffix=".php">./src</directory>
-        </whitelist>
-    </filter>
+        </include>
+    </coverage>
 
     <php>
         <ini name="date.timezone" value="UTC"/>
diff --git a/test/Header/ContentTransferEncodingTest.php b/test/Header/ContentTransferEncodingTest.php
index 913e0306..ed4aabef 100644
--- a/test/Header/ContentTransferEncodingTest.php
+++ b/test/Header/ContentTransferEncodingTest.php
@@ -99,7 +99,7 @@ public function testProvidingParametersIntroducesHeaderFolding(): void
         $header->setTransferEncoding('quoted-printable');
         $string = $header->toString();
 
-        $this->assertContains("Content-Transfer-Encoding: quoted-printable", $string);
+        $this->assertStringContainsString("Content-Transfer-Encoding: quoted-printable", $string);
     }
 
     /**
diff --git a/test/Header/GenericHeaderTest.php b/test/Header/GenericHeaderTest.php
index eca46fe6..8e3a373b 100644
--- a/test/Header/GenericHeaderTest.php
+++ b/test/Header/GenericHeaderTest.php
@@ -92,8 +92,8 @@ public function testCRLFsequencesAreEncodedOnToString($fieldValue): void
         $header->setFieldValue($fieldValue);
 
         $serialized = $header->toString();
-        $this->assertNotContains("\n", $serialized);
-        $this->assertNotContains("\r", $serialized);
+        $this->assertStringNotContainsString("\n", $serialized);
+        $this->assertStringNotContainsString("\r", $serialized);
     }
 
     /**
@@ -196,10 +196,10 @@ public function testChangeEncodingToAsciiNotAllowedWhenHeaderValueContainsUtf8Ch
         $subject = new GenericHeader();
         $subject->setFieldValue('Accents òàùèéì');
 
-        self::assertSame('UTF-8', $subject->getEncoding());
+        $this->assertSame('UTF-8', $subject->getEncoding());
 
         $subject->setEncoding('ASCII');
-        self::assertSame('UTF-8', $subject->getEncoding());
+        $this->assertSame('UTF-8', $subject->getEncoding());
     }
 
     public function testChangeEncodingBackToAscii(): void
@@ -207,39 +207,39 @@ public function testChangeEncodingBackToAscii(): void
         $subject = new GenericHeader('X-Test');
         $subject->setFieldValue('test');
 
-        self::assertSame('ASCII', $subject->getEncoding());
+        $this->assertSame('ASCII', $subject->getEncoding());
 
         $subject->setEncoding('UTF-8');
-        self::assertSame('UTF-8', $subject->getEncoding());
+        $this->assertSame('UTF-8', $subject->getEncoding());
 
         $subject->setEncoding('ASCII');
-        self::assertSame('ASCII', $subject->getEncoding());
+        $this->assertSame('ASCII', $subject->getEncoding());
     }
 
     public function testSetNullEncoding(): void
     {
         $subject = GenericHeader::fromString('X-Test: test');
-        self::assertSame('ASCII', $subject->getEncoding());
+        $this->assertSame('ASCII', $subject->getEncoding());
 
         $subject->setEncoding(null);
-        self::assertSame('ASCII', $subject->getEncoding());
+        $this->assertSame('ASCII', $subject->getEncoding());
     }
 
     public function testSettingFieldValueCanChangeEncoding(): void
     {
         $subject = GenericHeader::fromString('X-Test: test');
-        self::assertSame('ASCII', $subject->getEncoding());
+        $this->assertSame('ASCII', $subject->getEncoding());
 
         $subject->setFieldValue('Accents òàùèéì');
-        self::assertSame('UTF-8', $subject->getEncoding());
+        $this->assertSame('UTF-8', $subject->getEncoding());
     }
 
     public function testSettingTheSameEncoding(): void
     {
         $subject = GenericHeader::fromString('X-Test: test');
-        self::assertSame('ASCII', $subject->getEncoding());
+        $this->assertSame('ASCII', $subject->getEncoding());
 
         $subject->setEncoding('ASCII');
-        self::assertSame('ASCII', $subject->getEncoding());
+        $this->assertSame('ASCII', $subject->getEncoding());
     }
 }
diff --git a/test/Header/MessageIdTest.php b/test/Header/MessageIdTest.php
index 9c4705fc..4808eb1f 100644
--- a/test/Header/MessageIdTest.php
+++ b/test/Header/MessageIdTest.php
@@ -35,7 +35,7 @@ public function testAutoGeneration(): void
         $messageid = new Header\MessageId();
         $messageid->setId();
 
-        $this->assertContains('@', $messageid->getFieldValue());
+        $this->assertStringContainsString('@', $messageid->getFieldValue());
     }
 
     public function testAutoGenerationWithServerVars(): void
@@ -46,7 +46,7 @@ public function testAutoGenerationWithServerVars(): void
         $messageid = new Header\MessageId();
         $messageid->setId();
 
-        $this->assertContains('@server-name.test', $messageid->getFieldValue());
+        $this->assertStringContainsString('@server-name.test', $messageid->getFieldValue());
         $_SERVER = $serverBeforeTest;
     }
 
diff --git a/test/Header/SubjectTest.php b/test/Header/SubjectTest.php
index b2c34504..c83f55d4 100644
--- a/test/Header/SubjectTest.php
+++ b/test/Header/SubjectTest.php
@@ -135,10 +135,10 @@ public function testChangeEncodingToAsciiNotAllowedWhenSubjectContainsUtf8Charac
         $subject = new Header\Subject();
         $subject->setSubject('Accents òàùèéì');
 
-        self::assertSame('UTF-8', $subject->getEncoding());
+        $this->assertSame('UTF-8', $subject->getEncoding());
 
         $subject->setEncoding('ASCII');
-        self::assertSame('UTF-8', $subject->getEncoding());
+        $this->assertSame('UTF-8', $subject->getEncoding());
     }
 
     public function testChangeEncodingBackToAscii(): void
@@ -146,39 +146,39 @@ public function testChangeEncodingBackToAscii(): void
         $subject = new Header\Subject();
         $subject->setSubject('test');
 
-        self::assertSame('ASCII', $subject->getEncoding());
+        $this->assertSame('ASCII', $subject->getEncoding());
 
         $subject->setEncoding('UTF-8');
-        self::assertSame('UTF-8', $subject->getEncoding());
+        $this->assertSame('UTF-8', $subject->getEncoding());
 
         $subject->setEncoding('ASCII');
-        self::assertSame('ASCII', $subject->getEncoding());
+        $this->assertSame('ASCII', $subject->getEncoding());
     }
 
     public function testSetNullEncoding(): void
     {
         $subject = Header\Subject::fromString('Subject: test');
-        self::assertSame('ASCII', $subject->getEncoding());
+        $this->assertSame('ASCII', $subject->getEncoding());
 
         $subject->setEncoding(null);
-        self::assertSame('ASCII', $subject->getEncoding());
+        $this->assertSame('ASCII', $subject->getEncoding());
     }
 
     public function testSettingSubjectCanChangeEncoding(): void
     {
         $subject = Header\Subject::fromString('Subject: test');
-        self::assertSame('ASCII', $subject->getEncoding());
+        $this->assertSame('ASCII', $subject->getEncoding());
 
         $subject->setSubject('Accents òàùèéì');
-        self::assertSame('UTF-8', $subject->getEncoding());
+        $this->assertSame('UTF-8', $subject->getEncoding());
     }
 
     public function testSettingTheSameEncoding(): void
     {
         $subject = Header\Subject::fromString('Subject: test');
-        self::assertSame('ASCII', $subject->getEncoding());
+        $this->assertSame('ASCII', $subject->getEncoding());
 
         $subject->setEncoding('ASCII');
-        self::assertSame('ASCII', $subject->getEncoding());
+        $this->assertSame('ASCII', $subject->getEncoding());
     }
 }
diff --git a/test/HeadersTest.php b/test/HeadersTest.php
index d9b40005..41bcd68c 100644
--- a/test/HeadersTest.php
+++ b/test/HeadersTest.php
@@ -606,7 +606,7 @@ public function testGetPluginClassLoaderEmitsDeprecationNotice(): void
         $this->setDeprecationErrorHandler();
         $headers = new Mail\Headers();
 
-        $this->expectException(Deprecated::class);
+        $this->expectDeprecation();
         $this->expectExceptionMessage('getPluginClassLoader is deprecated');
         $headers->getPluginClassLoader();
     }
@@ -618,9 +618,9 @@ public function testSetPluginClassLoaderEmitsDeprecationNotice(): void
     {
         $this->setDeprecationErrorHandler();
         $headers = new Mail\Headers();
-        $loader  = $this->prophesize(PluginClassLocator::class)->reveal();
+        $loader  = $this->createMock(PluginClassLocator::class);
 
-        $this->expectException(Deprecated::class);
+        $this->expectDeprecation();
         $this->expectExceptionMessage('deprecated');
         $headers->setPluginClassLoader($loader);
     }
@@ -635,7 +635,7 @@ public function testGetHeaderLocatorReturnsHeaderLocatorInstanceByDefault(): voi
     public function testCanInjectAlternateHeaderLocatorInstance(): void
     {
         $headers = new Mail\Headers();
-        $locator = $this->prophesize(Mail\Header\HeaderLocatorInterface::class)->reveal();
+        $locator = $this->createMock(Mail\Header\HeaderLocatorInterface::class);
 
         $headers->setHeaderLocator($locator);
         $this->assertSame($locator, $headers->getHeaderLocator());
diff --git a/test/MessageTest.php b/test/MessageTest.php
index c3920070..3fb98d6f 100644
--- a/test/MessageTest.php
+++ b/test/MessageTest.php
@@ -582,7 +582,7 @@ public function testSettingUtf8MailBodyFromSinglePartMimeUtf8MessageSetsAppropri
         $this->message->setEncoding('UTF-8');
         $this->message->setBody($body);
 
-        $this->assertContains(
+        $this->assertStringContainsString(
             'Content-Type: text/plain;' . Headers::FOLDING . 'charset="utf-8"' . Headers::EOL
             . 'Content-Transfer-Encoding: quoted-printable' . Headers::EOL,
             $this->message->getHeaders()->toString()
@@ -630,10 +630,10 @@ public function testRetrievingBodyTextFromMessageWithMultiPartMimeBodyReturnsMim
 
         $text = $this->message->getBodyText();
         $this->assertEquals($body->generateMessage(Headers::EOL), $text);
-        $this->assertContains('--foo-bar', $text);
-        $this->assertContains('--foo-bar--', $text);
-        $this->assertContains('Content-Type: text/plain', $text);
-        $this->assertContains('Content-Type: text/html', $text);
+        $this->assertStringContainsString('--foo-bar', $text);
+        $this->assertStringContainsString('--foo-bar--', $text);
+        $this->assertStringContainsString('Content-Type: text/plain', $text);
+        $this->assertStringContainsString('Content-Type: text/html', $text);
     }
 
     public function testEncodingIsAsciiByDefault(): void
@@ -666,23 +666,23 @@ public function testSettingNonAsciiEncodingForcesMimeEncodingOfSomeHeaders(): vo
         $test = $this->message->getHeaders()->toString();
 
         $expected = '=?UTF-8?Q?Laminas=20DevTeam?=';
-        $this->assertContains($expected, $test);
-        $this->assertContains('<test@example.com>', $test);
+        $this->assertStringContainsString($expected, $test);
+        $this->assertStringContainsString('<test@example.com>', $test);
 
         $expected = "=?UTF-8?Q?Matthew=20Weier=20O'Phinney?=";
-        $this->assertContains($expected, $test, $test);
-        $this->assertContains('<matthew@example.com>', $test);
+        $this->assertStringContainsString($expected, $test, $test);
+        $this->assertStringContainsString('<matthew@example.com>', $test);
 
         $expected = '=?UTF-8?Q?Laminas=20Contributors=20List?=';
-        $this->assertContains($expected, $test);
-        $this->assertContains('<list@example.com>', $test);
+        $this->assertStringContainsString($expected, $test);
+        $this->assertStringContainsString('<list@example.com>', $test);
 
         $expected = '=?UTF-8?Q?Laminas=20CR=20Team?=';
-        $this->assertContains($expected, $test);
-        $this->assertContains('<devs@example.com>', $test);
+        $this->assertStringContainsString($expected, $test);
+        $this->assertStringContainsString('<devs@example.com>', $test);
 
         $expected = 'Subject: =?UTF-8?Q?This=20is=20a=20subject?=';
-        $this->assertContains($expected, $test);
+        $this->assertStringContainsString($expected, $test);
     }
 
     /**
@@ -785,8 +785,8 @@ public function testDetectsCRLFInjectionViaSubject(): void
         $this->message->setSubject(implode(Headers::EOL, $subject));
 
         $serializedHeaders = $this->message->getHeaders()->toString();
-        $this->assertContains('example', $serializedHeaders);
-        $this->assertNotContains("\r\n<html>", $serializedHeaders);
+        $this->assertStringContainsString('example', $serializedHeaders);
+        $this->assertStringNotContainsString("\r\n<html>", $serializedHeaders);
     }
 
     public function testHeaderUnfoldingWorksAsExpectedForMultipartMessages(): void
@@ -820,8 +820,8 @@ public function testHeaderUnfoldingWorksAsExpectedForMultipartMessages(): void
 
         $contentType = $this->message->getHeaders()->get('Content-Type');
         $this->assertInstanceOf(ContentType::class, $contentType);
-        $this->assertContains('multipart/alternative', $contentType->getFieldValue());
-        $this->assertContains($multipartContent->getMime()->boundary(), $contentType->getFieldValue());
+        $this->assertStringContainsString('multipart/alternative', $contentType->getFieldValue());
+        $this->assertStringContainsString($multipartContent->getMime()->boundary(), $contentType->getFieldValue());
     }
 
     /**
@@ -832,7 +832,7 @@ public function testCanParseMultipartReport(): void
         $raw = file_get_contents(__DIR__ . '/_files/laminas-mail-19.txt');
         $message = Message::fromString($raw);
         $this->assertInstanceOf(Message::class, $message);
-        $this->assertInternalType('string', $message->getBody());
+        $this->assertIsString($message->getBody());
 
         $headers = $message->getHeaders();
         $this->assertCount(8, $headers);
@@ -861,7 +861,7 @@ public function testMailHeaderContainsZeroValue(): void
             ."I am a test message\r\n";
 
         $msg = Message::fromString($message);
-        $this->assertContains('X-Spam-Score: 0', $msg->toString());
+        $this->assertStringContainsString('X-Spam-Score: 0', $msg->toString());
     }
 
     /**
@@ -882,7 +882,7 @@ public function testMessageSubjectFromString(): void
             . ' =?UTF-8?Q?vowels=20=C3=B2=C3=A0=C3=B9=C3=A8=C3=A9=C3=AC?=';
         $mail = Message::fromString($rawMessage);
 
-        self::assertContains(
+        $this->assertStringContainsString(
             'Subject: =?UTF-8?Q?Non=20=E2=80=9Cascii=E2=80=9D=20characters=20like=20accented=20?=' . "\r\n"
             . ' =?UTF-8?Q?vowels=20=C3=B2=C3=A0=C3=B9=C3=A8=C3=A9=C3=AC?=' . "\r\n",
             $mail->toString()
@@ -894,7 +894,7 @@ public function testMessageSubjectSetSubject(): void
         $mail = new Message();
         $mail->setSubject('Non “ascii” characters like accented vowels òàùèéì');
 
-        self::assertContains(
+        $this->assertStringContainsString(
             'Subject: =?UTF-8?Q?Non=20=E2=80=9Cascii=E2=80=9D=20characters=20like=20accented=20?=' . "\r\n"
             . ' =?UTF-8?Q?vowels=20=C3=B2=C3=A0=C3=B9=C3=A8=C3=A9=C3=AC?=' . "\r\n",
             $mail->toString()
@@ -907,7 +907,7 @@ public function testCorrectHeaderEncodingAddHeader(): void
         $header = new GenericHeader('X-Test', 'Non “ascii” characters like accented vowels òàùèéì');
         $mail->getHeaders()->addHeader($header);
 
-        self::assertContains(
+        $this->assertStringContainsString(
             'X-Test: =?UTF-8?Q?Non=20=E2=80=9Cascii=E2=80=9D=20characters=20like=20accented=20?=' . "\r\n"
             . ' =?UTF-8?Q?vowels=20=C3=B2=C3=A0=C3=B9=C3=A8=C3=A9=C3=AC?=' . "\r\n",
             $mail->toString()
@@ -922,7 +922,7 @@ public function testCorrectHeaderEncodingSetHeaders(): void
         $headers->addHeader($header);
         $mail->setHeaders($headers);
 
-        self::assertContains(
+        $this->assertStringContainsString(
             'X-Test: =?UTF-8?Q?Non=20=E2=80=9Cascii=E2=80=9D=20characters=20like=20accented=20?=' . "\r\n"
             . ' =?UTF-8?Q?vowels=20=C3=B2=C3=A0=C3=B9=C3=A8=C3=A9=C3=AC?=' . "\r\n",
             $mail->toString()
@@ -937,7 +937,7 @@ public function testCorrectHeaderEncodingFromString(): void
         $header = GenericHeader::fromString($str);
         $mail->getHeaders()->addHeader($header);
 
-        self::assertContains(
+        $this->assertStringContainsString(
             'X-Test: =?UTF-8?Q?Non=20=E2=80=9Cascii=E2=80=9D=20characters=20like=20accented=20?=' . "\r\n"
             . ' =?UTF-8?Q?vowels=20=C3=B2=C3=A0=C3=B9=C3=A8=C3=A9=C3=AC?=' . "\r\n",
             $mail->toString()
@@ -955,7 +955,7 @@ public function testCorrectHeaderEncodingFromStringAndSetHeaders(): void
         $headers->addHeader($header);
         $mail->setHeaders($headers);
 
-        self::assertContains(
+        $this->assertStringContainsString(
             'X-Test: =?UTF-8?Q?Non=20=E2=80=9Cascii=E2=80=9D=20characters=20like=20accented=20?=' . "\r\n"
             . ' =?UTF-8?Q?vowels=20=C3=B2=C3=A0=C3=B9=C3=A8=C3=A9=C3=AC?=' . "\r\n",
             $mail->toString()
@@ -968,8 +968,8 @@ public function testMessageSubjectEncodingWhenEncodingSetAfterTheSubject(): void
         $mail->setSubject('hello world');
         $mail->setEncoding('UTF-8');
 
-        self::assertSame('UTF-8', $mail->getHeaders()->get('subject')->getEncoding());
-        self::assertSame(
+        $this->assertSame('UTF-8', $mail->getHeaders()->get('subject')->getEncoding());
+        $this->assertSame(
             'Subject: =?UTF-8?Q?hello=20world?=',
             $mail->getHeaders()->get('subject')->toString()
         );
@@ -981,8 +981,8 @@ public function testMessageSubjectEncodingWhenEcodingSetBeforeTheSubject(): void
         $mail->setEncoding('UTF-8');
         $mail->setSubject('hello world');
 
-        self::assertSame('UTF-8', $mail->getHeaders()->get('subject')->getEncoding());
-        self::assertSame(
+        $this->assertSame('UTF-8', $mail->getHeaders()->get('subject')->getEncoding());
+        $this->assertSame(
             'Subject: =?UTF-8?Q?hello=20world?=',
             $mail->getHeaders()->get('subject')->toString()
         );
diff --git a/test/Protocol/SmtpPluginManagerFactoryTest.php b/test/Protocol/SmtpPluginManagerFactoryTest.php
index 2928290b..3e68e5c0 100644
--- a/test/Protocol/SmtpPluginManagerFactoryTest.php
+++ b/test/Protocol/SmtpPluginManagerFactoryTest.php
@@ -14,20 +14,25 @@
 use Laminas\Mail\Protocol\SmtpPluginManagerFactory;
 use Laminas\ServiceManager\ServiceLocatorInterface;
 use PHPUnit\Framework\TestCase;
+use ReflectionClass;
 
 class SmtpPluginManagerFactoryTest extends TestCase
 {
     public function testFactoryReturnsPluginManager(): void
     {
-        $container = $this->prophesize(ContainerInterface::class)->reveal();
+        $container = $this->createMock(ContainerInterface::class);
         $factory = new SmtpPluginManagerFactory();
 
         $plugins = $factory($container, SmtpPluginManager::class);
         $this->assertInstanceOf(SmtpPluginManager::class, $plugins);
 
         if (method_exists($plugins, 'configure')) {
+            $reflectionClass = new ReflectionClass($plugins);
+            $creationContextProperty = $reflectionClass->getProperty('creationContext');
+            $creationContextProperty->setAccessible(true);
+
             // laminas-servicemanager v3
-            $this->assertAttributeSame($container, 'creationContext', $plugins);
+            $this->assertEquals($container, $creationContextProperty->getValue($plugins));
         } else {
             // laminas-servicemanager v2
             $this->assertSame($container, $plugins->getServiceLocator());
@@ -39,8 +44,8 @@ public function testFactoryReturnsPluginManager(): void
      */
     public function testFactoryConfiguresPluginManagerUnderContainerInterop(): void
     {
-        $container = $this->prophesize(ContainerInterface::class)->reveal();
-        $smtp = $this->prophesize(Smtp::class)->reveal();
+        $container = $this->createMock(ContainerInterface::class);
+        $smtp = $this->createMock(Smtp::class);
 
         $factory = new SmtpPluginManagerFactory();
         $plugins = $factory($container, SmtpPluginManager::class, [
@@ -56,10 +61,9 @@ public function testFactoryConfiguresPluginManagerUnderContainerInterop(): void
      */
     public function testFactoryConfiguresPluginManagerUnderServiceManagerV2(): void
     {
-        $container = $this->prophesize(ServiceLocatorInterface::class);
-        $container->willImplement(ContainerInterface::class);
+        $container = $this->createMock(ServiceLocatorInterface::class);
 
-        $smtp = $this->prophesize(Smtp::class)->reveal();
+        $smtp = $this->createMock(Smtp::class);
 
         $factory = new SmtpPluginManagerFactory();
         $factory->setCreationOptions([
@@ -68,7 +72,7 @@ public function testFactoryConfiguresPluginManagerUnderServiceManagerV2(): void
             ],
         ]);
 
-        $plugins = $factory->createService($container->reveal());
+        $plugins = $factory->createService($container);
         $this->assertSame($smtp, $plugins->get('test'));
     }
 }
diff --git a/test/Protocol/SmtpTest.php b/test/Protocol/SmtpTest.php
index c7be4270..8da08a1a 100644
--- a/test/Protocol/SmtpTest.php
+++ b/test/Protocol/SmtpTest.php
@@ -109,7 +109,7 @@ public function testConnectHasVerboseErrors(): void
         $smtp = new TestAsset\ErroneousSmtp();
 
         $this->expectException(Exception\RuntimeException::class);
-        $this->expectExceptionMessageRegExp('/nonexistentremote/');
+        $this->expectExceptionMessageMatches('/nonexistentremote/');
 
         $smtp->connect('nonexistentremote');
     }
@@ -123,7 +123,7 @@ public function testCanAvoidQuitRequest(): void
         $this->connection->helo();
         $this->connection->disconnect();
 
-        $this->assertContains('QUIT', $this->connection->getLog());
+        $this->assertStringContainsString('QUIT', $this->connection->getLog());
 
         $this->connection->setUseCompleteQuit(false);
         $this->assertFalse($this->connection->useCompleteQuit());
@@ -133,7 +133,7 @@ public function testCanAvoidQuitRequest(): void
         $this->connection->helo();
         $this->connection->disconnect();
 
-        $this->assertNotContains('QUIT', $this->connection->getLog());
+        $this->assertStringNotContainsString('QUIT', $this->connection->getLog());
 
         $connection = new SmtpProtocolSpy([
             'use_complete_quit' => false,
diff --git a/test/Storage/ImapTest.php b/test/Storage/ImapTest.php
index dc4726bc..952bb624 100644
--- a/test/Storage/ImapTest.php
+++ b/test/Storage/ImapTest.php
@@ -681,7 +681,7 @@ public function testStore(): void
         $result = $protocol->store(['\Flagged'], 1, null, '', false);
         $this->assertContains('\Flagged', $result[1]);
         $result = $protocol->store(['\Flagged'], 1, null, '-', false);
-        $this->assertNotContains('\Flagged', $result[1]);
+        $this->assertStringNotContainsString('\Flagged', $result[1]);
         $result = $protocol->store(['\Flagged'], 1, null, '+', false);
         $this->assertContains('\Flagged', $result[1]);
     }
diff --git a/test/Transport/FactoryTest.php b/test/Transport/FactoryTest.php
index c5768a60..9e1e8909 100644
--- a/test/Transport/FactoryTest.php
+++ b/test/Transport/FactoryTest.php
@@ -13,6 +13,7 @@
 use Laminas\Mail\Transport\Sendmail;
 use Laminas\Stdlib\ArrayObject;
 use PHPUnit\Framework\TestCase;
+use Laminas\Mail\Transport\Exception;
 use Laminas\Mail\Transport\File;
 use Laminas\Mail\Transport\Smtp;
 
@@ -23,11 +24,11 @@ class FactoryTest extends TestCase
 {
     /**
      * @dataProvider invalidSpecTypeProvider
-     * @expectedException \Laminas\Mail\Transport\Exception\InvalidArgumentException
      * @param $spec
      */
     public function testInvalidSpecThrowsInvalidArgumentException($spec): void
     {
+        $this->expectException(Exception\InvalidArgumentException::class);
         Factory::create($spec);
     }
 
@@ -128,11 +129,11 @@ public function testCanUseTraversableAsSpec(): void
 
     /**
      * @dataProvider invalidClassProvider
-     * @expectedException \Laminas\Mail\Transport\Exception\DomainException
      * @param $class
      */
     public function testInvalidClassThrowsDomainException($class): void
     {
+        $this->expectException(Exception\DomainException::class);
         Factory::create([
             'type' => $class,
         ]);
diff --git a/test/Transport/FileOptionsTest.php b/test/Transport/FileOptionsTest.php
index b6fb7774..c0e9a906 100644
--- a/test/Transport/FileOptionsTest.php
+++ b/test/Transport/FileOptionsTest.php
@@ -34,9 +34,9 @@ public function testPathIsSysTempDirByDefault(): void
     public function testDefaultCallbackIsSetByDefault(): void
     {
         $callback = $this->options->getCallback();
-        $this->assertInternalType('callable', $callback);
+        $this->assertIsCallable($callback);
         $test     = $callback('');
-        $this->assertRegExp('#^LaminasMail_\d+_\d+\.eml$#', $test);
+        $this->assertMatchesRegularExpression('#^LaminasMail_\d+_\d+\.eml$#', $test);
     }
 
     public function testPathIsMutable(): void
diff --git a/test/Transport/SendmailTest.php b/test/Transport/SendmailTest.php
index e95bc520..cc447729 100644
--- a/test/Transport/SendmailTest.php
+++ b/test/Transport/SendmailTest.php
@@ -91,12 +91,12 @@ public function testReceivesMailArtifactsOnUnixSystems(): void
         $this->assertEquals('Example Test <test@example.com>', $this->to);
         $this->assertEquals('Testing Laminas\Mail\Transport\Sendmail', $this->subject);
         $this->assertEquals('This is only a test.', trim($this->message));
-        $this->assertNotContains("To: Example Test <test@example.com>\n", $this->additional_headers);
-        $this->assertContains("Cc: matthew@example.com\n", $this->additional_headers);
-        $this->assertContains("Bcc: \"Example, List\" <list@example.com>\n", $this->additional_headers);
-        $this->assertContains("From: test@example.com,\n Matthew <matthew@example.com>\n", $this->additional_headers);
-        $this->assertContains("X-Foo-Bar: Matthew\n", $this->additional_headers);
-        $this->assertContains("Sender: Ralph Schindler <ralph@example.com>\n", $this->additional_headers);
+        $this->assertStringNotContainsString("To: Example Test <test@example.com>\n", $this->additional_headers);
+        $this->assertStringContainsString("Cc: matthew@example.com\n", $this->additional_headers);
+        $this->assertStringContainsString("Bcc: \"Example, List\" <list@example.com>\n", $this->additional_headers);
+        $this->assertStringContainsString("From: test@example.com,\n Matthew <matthew@example.com>\n", $this->additional_headers);
+        $this->assertStringContainsString("X-Foo-Bar: Matthew\n", $this->additional_headers);
+        $this->assertStringContainsString("Sender: Ralph Schindler <ralph@example.com>\n", $this->additional_headers);
         $this->assertEquals('-R hdrs -f\'ralph@example.com\'', $this->additional_parameters);
     }
 
@@ -112,15 +112,15 @@ public function testReceivesMailArtifactsOnWindowsSystems(): void
         $this->assertEquals('test@example.com', $this->to);
         $this->assertEquals('Testing Laminas\Mail\Transport\Sendmail', $this->subject);
         $this->assertEquals('This is only a test.', trim($this->message));
-        $this->assertContains("To: Example Test <test@example.com>\r\n", $this->additional_headers);
-        $this->assertContains("Cc: matthew@example.com\r\n", $this->additional_headers);
-        $this->assertContains("Bcc: \"Example, List\" <list@example.com>\r\n", $this->additional_headers);
-        $this->assertContains(
+        $this->assertStringContainsString("To: Example Test <test@example.com>\r\n", $this->additional_headers);
+        $this->assertStringContainsString("Cc: matthew@example.com\r\n", $this->additional_headers);
+        $this->assertStringContainsString("Bcc: \"Example, List\" <list@example.com>\r\n", $this->additional_headers);
+        $this->assertStringContainsString(
             "From: test@example.com,\r\n Matthew <matthew@example.com>\r\n",
             $this->additional_headers
         );
-        $this->assertContains("X-Foo-Bar: Matthew\r\n", $this->additional_headers);
-        $this->assertContains("Sender: Ralph Schindler <ralph@example.com>\r\n", $this->additional_headers);
+        $this->assertStringContainsString("X-Foo-Bar: Matthew\r\n", $this->additional_headers);
+        $this->assertStringContainsString("Sender: Ralph Schindler <ralph@example.com>\r\n", $this->additional_headers);
         $this->assertNull($this->additional_parameters);
     }
 
@@ -133,7 +133,7 @@ public function testLinesStartingWithFullStopsArePreparedProperlyForWindows(): v
         $message = $this->getMessage();
         $message->setBody("This is the first line.\n. This is the second");
         $this->transport->send($message);
-        $this->assertContains("line.\n.. This", trim($this->message));
+        $this->assertStringContainsString("line.\n.. This", trim($this->message));
     }
 
     public function testAssertSubjectEncoded(): void
@@ -165,7 +165,7 @@ public function testValidEmailLocaDomainInFromHeader(): void
         $message->setSubject('TestSubject');
 
         $this->transport->send($message);
-        $this->assertContains('From: Foo Bar <"foo-bar"@domain>', $this->additional_headers);
+        $this->assertStringContainsString('From: Foo Bar <"foo-bar"@domain>', $this->additional_headers);
     }
 
     /**
@@ -177,17 +177,17 @@ public function testPrepareParametersEscapesSenderUsingEscapeShellArg(): void
         $injectedEmail = 'user@xenial(tmp1 -be ${run{${substr{0}{1}{$spool_directory}}usr${substr{0}{1}{$spool_directory}}bin${substr{0}{1}{$spool_directory}}touch${substr{10}{1}{$tod_log}}${substr{0}{1}{$spool_directory}}tmp${substr{0}{1}{$spool_directory}}test}}  tmp2)';
         // @codingStandardsIgnoreEnd
 
-        $sender = $this->prophesize(AddressInterface::class);
-        $sender->getEmail()->willReturn($injectedEmail);
+        $sender = $this->createMock(AddressInterface::class);
+        $sender->method('getEmail')->willReturn($injectedEmail);
 
-        $message = $this->prophesize(Message::class);
-        $message->getSender()->will([$sender, 'reveal']);
-        $message->getFrom()->shouldNotBeCalled();
+        $message = $this->createMock(Message::class);
+        $message->method('getSender')->willReturn($sender);
+        $message->expects($this->never())->method('getFrom');
 
         $r = new ReflectionMethod($this->transport, 'prepareParameters');
         $r->setAccessible(true);
 
-        $parameters = $r->invoke($this->transport, $message->reveal());
+        $parameters = $r->invoke($this->transport, $message);
         $this->assertEquals(' -f' . escapeshellarg($injectedEmail), $parameters);
     }
 
@@ -200,20 +200,20 @@ public function testPrepareParametersEscapesFromAddressUsingEscapeShellArg(): vo
         $injectedEmail = 'user@xenial(tmp1 -be ${run{${substr{0}{1}{$spool_directory}}usr${substr{0}{1}{$spool_directory}}bin${substr{0}{1}{$spool_directory}}touch${substr{10}{1}{$tod_log}}${substr{0}{1}{$spool_directory}}tmp${substr{0}{1}{$spool_directory}}test}}  tmp2)';
         // @codingStandardsIgnoreEnd
 
-        $address = $this->prophesize(AddressInterface::class);
-        $address->getEmail()->willReturn($injectedEmail)->shouldBeCalledTimes(2);
+        $address = $this->createMock(AddressInterface::class);
+        $address->expects($this->exactly(2))->method('getEmail')->willReturn($injectedEmail);
 
         $from = new AddressList();
-        $from->add($address->reveal());
+        $from->add($address);
 
-        $message = $this->prophesize(Message::class);
-        $message->getSender()->willReturn(null);
-        $message->getFrom()->willReturn($from);
+        $message = $this->createMock(Message::class);
+        $message->method('getSender')->willReturn(null);
+        $message->method('getFrom')->willReturn($from);
 
         $r = new ReflectionMethod($this->transport, 'prepareParameters');
         $r->setAccessible(true);
 
-        $parameters = $r->invoke($this->transport, $message->reveal());
+        $parameters = $r->invoke($this->transport, $message);
         $this->assertEquals(' -f' . escapeshellarg($injectedEmail), $parameters);
     }
 
@@ -236,7 +236,7 @@ public function testAllowMessageWithEmptyToHeaderButHasCcHeader(): void
                 ->setBody('This is only a test.');
 
         $this->transport->send($message);
-        $this->assertContains('Sender: Ralph Schindler <ralph@example.com>', $this->additional_headers);
+        $this->assertStringContainsString('Sender: Ralph Schindler <ralph@example.com>', $this->additional_headers);
     }
 
     public function testAllowMessageWithEmptyToHeaderButHasBccHeader(): void
@@ -248,7 +248,7 @@ public function testAllowMessageWithEmptyToHeaderButHasBccHeader(): void
                 ->setBody('This is only a test.');
 
         $this->transport->send($message);
-        $this->assertContains('Sender: Ralph Schindler <ralph@example.com>', $this->additional_headers);
+        $this->assertStringContainsString('Sender: Ralph Schindler <ralph@example.com>', $this->additional_headers);
     }
 
     public function testDoNotAllowMessageWithoutToAndCcAndBccHeaders(): void
@@ -279,8 +279,8 @@ public function testHeadersToAndSubjectAreNotDuplicated(): void
         $this->assertEquals('matthew@example.org', $this->to);
         $this->assertEquals('Greetings and Salutations!', $this->subject);
 
-        $this->assertNotRegExp('/^To: matthew\@example\.org$/m', $this->additional_headers);
-        $this->assertNotRegExp('/^Subject: Greetings and Salutations!$/m', $this->additional_headers);
+        $this->assertDoesNotMatchRegularExpression('/^To: matthew\@example\.org$/m', $this->additional_headers);
+        $this->assertDoesNotMatchRegularExpression('/^Subject: Greetings and Salutations!$/m', $this->additional_headers);
     }
 
     public function additionalParametersContainingFromSwitch(): iterable
diff --git a/test/Transport/SmtpTest.php b/test/Transport/SmtpTest.php
index b2183360..07a1f9c9 100644
--- a/test/Transport/SmtpTest.php
+++ b/test/Transport/SmtpTest.php
@@ -95,10 +95,10 @@ public function testSendMailWithEnvelopeFrom(): void
         $this->transport->send($message);
 
         $data = $this->connection->getLog();
-        $this->assertContains('MAIL FROM:<mailer@example.com>', $data);
-        $this->assertContains('RCPT TO:<matthew@example.com>', $data);
-        $this->assertContains('RCPT TO:<list@example.com>', $data);
-        $this->assertContains("From: test@example.com,\r\n Matthew <matthew@example.com>\r\n", $data);
+        $this->assertStringContainsString('MAIL FROM:<mailer@example.com>', $data);
+        $this->assertStringContainsString('RCPT TO:<matthew@example.com>', $data);
+        $this->assertStringContainsString('RCPT TO:<list@example.com>', $data);
+        $this->assertStringContainsString("From: test@example.com,\r\n Matthew <matthew@example.com>\r\n", $data);
     }
 
     public function testSendMailWithEnvelopeTo(): void
@@ -111,9 +111,9 @@ public function testSendMailWithEnvelopeTo(): void
         $this->transport->send($message);
 
         $data = $this->connection->getLog();
-        $this->assertContains('MAIL FROM:<ralph@example.com>', $data);
-        $this->assertContains('RCPT TO:<users@example.com>', $data);
-        $this->assertContains('To: Example Test <test@example.com>', $data);
+        $this->assertStringContainsString('MAIL FROM:<ralph@example.com>', $data);
+        $this->assertStringContainsString('RCPT TO:<users@example.com>', $data);
+        $this->assertStringContainsString('To: Example Test <test@example.com>', $data);
     }
 
     public function testSendMailWithEnvelope(): void
@@ -130,9 +130,9 @@ public function testSendMailWithEnvelope(): void
         $this->assertEquals($to, $this->connection->getRecipients());
 
         $data = $this->connection->getLog();
-        $this->assertContains('MAIL FROM:<mailer@example.com>', $data);
-        $this->assertContains('RCPT TO:<users@example.com>', $data);
-        $this->assertContains('RCPT TO:<dev@example.com>', $data);
+        $this->assertStringContainsString('MAIL FROM:<mailer@example.com>', $data);
+        $this->assertStringContainsString('RCPT TO:<users@example.com>', $data);
+        $this->assertStringContainsString('RCPT TO:<dev@example.com>', $data);
     }
 
     public function testSendMinimalMail(): void
@@ -154,7 +154,7 @@ public function testSendMinimalMail(): void
 
         $this->transport->send($message);
 
-        $this->assertContains($expectedMessage, $this->connection->getLog());
+        $this->assertStringContainsString($expectedMessage, $this->connection->getLog());
     }
 
     public function testSendMinimalMailWithoutSender(): void
@@ -176,7 +176,7 @@ public function testSendMinimalMailWithoutSender(): void
 
         $this->transport->send($message);
 
-        $this->assertContains($expectedMessage, $this->connection->getLog());
+        $this->assertStringContainsString($expectedMessage, $this->connection->getLog());
     }
 
     public function testReceivesMailArtifacts(): void
@@ -188,15 +188,15 @@ public function testReceivesMailArtifacts(): void
         $this->assertEquals($expectedRecipients, $this->connection->getRecipients());
 
         $data = $this->connection->getLog();
-        $this->assertContains('MAIL FROM:<ralph@example.com>', $data);
-        $this->assertContains('To: Example Test <test@example.com>', $data);
-        $this->assertContains('Subject: Testing Laminas\Mail\Transport\Sendmail', $data);
-        $this->assertContains("Cc: matthew@example.com\r\n", $data);
-        $this->assertNotContains("Bcc: \"Example List\" <list@example.com>\r\n", $data);
-        $this->assertContains("From: test@example.com,\r\n Matthew <matthew@example.com>\r\n", $data);
-        $this->assertContains("X-Foo-Bar: Matthew\r\n", $data);
-        $this->assertContains("Sender: Ralph Schindler <ralph@example.com>\r\n", $data);
-        $this->assertContains("\r\n\r\nThis is only a test.", $data, $data);
+        $this->assertStringContainsString('MAIL FROM:<ralph@example.com>', $data);
+        $this->assertStringContainsString('To: Example Test <test@example.com>', $data);
+        $this->assertStringContainsString('Subject: Testing Laminas\Mail\Transport\Sendmail', $data);
+        $this->assertStringContainsString("Cc: matthew@example.com\r\n", $data);
+        $this->assertStringNotContainsString("Bcc: \"Example List\" <list@example.com>\r\n", $data);
+        $this->assertStringContainsString("From: test@example.com,\r\n Matthew <matthew@example.com>\r\n", $data);
+        $this->assertStringContainsString("X-Foo-Bar: Matthew\r\n", $data);
+        $this->assertStringContainsString("Sender: Ralph Schindler <ralph@example.com>\r\n", $data);
+        $this->assertStringContainsString("\r\n\r\nThis is only a test.", $data, $data);
     }
 
     public function testCanUseAuthenticationExtensionsViaPluginManager(): void
@@ -328,7 +328,7 @@ public function testAutoReconnect(): void
         $reflClass             = new \ReflectionClass($this->transport);
         $connectedTimeProperty = $reflClass->getProperty('connectedTime');
 
-        self::assertNotNull($connectedTimeProperty);
+        $this->assertNotNull($connectedTimeProperty);
         $connectedTimeProperty->setAccessible(true);
         $connectedTimeAfterFirstMail = $connectedTimeProperty->getValue($this->transport);
         $this->assertNotNull($connectedTimeAfterFirstMail);