diff --git a/composer.json b/composer.json
index 9de761e07b..a42168dc5f 100644
--- a/composer.json
+++ b/composer.json
@@ -36,7 +36,7 @@
         "ext-xmlwriter": "*"
     },
     "require-dev": {
-        "phpunit/phpunit": "^4.0 || ^5.0 || ^6.0 || ^7.0 || ^8.0 || ^9.3.4"
+        "phpunit/phpunit": "^8.0 || ^9.3.4"
     },
     "bin": [
         "bin/phpcbf",
diff --git a/tests/AllTests.php b/tests/AllTests.php
index 4fa41d9d9c..0002ab7daa 100644
--- a/tests/AllTests.php
+++ b/tests/AllTests.php
@@ -11,23 +11,7 @@
 
 require_once 'Core/AllTests.php';
 require_once 'Standards/AllSniffs.php';
-
-// PHPUnit 7 made the TestSuite run() method incompatible with
-// older PHPUnit versions due to return type hints, so maintain
-// two different suite objects.
-$phpunit7 = false;
-if (class_exists('\PHPUnit\Runner\Version') === true) {
-    $version = \PHPUnit\Runner\Version::id();
-    if (version_compare($version, '7.0', '>=') === true) {
-        $phpunit7 = true;
-    }
-}
-
-if ($phpunit7 === true) {
-    include_once 'TestSuite7.php';
-} else {
-    include_once 'TestSuite.php';
-}
+require_once 'TestSuite.php';
 
 class PHP_CodeSniffer_AllTests
 {
diff --git a/tests/Core/AbstractMethodUnitTest.php b/tests/Core/AbstractMethodUnitTest.php
index c4c86c3e4e..e806a07622 100644
--- a/tests/Core/AbstractMethodUnitTest.php
+++ b/tests/Core/AbstractMethodUnitTest.php
@@ -42,11 +42,9 @@ abstract class AbstractMethodUnitTest extends TestCase
      * The test case file for a unit test class has to be in the same directory
      * directory and use the same file name as the test class, using the .inc extension.
      *
-     * @beforeClass
-     *
      * @return void
      */
-    public static function initializeFile()
+    public static function setUpBeforeClass(): void
     {
         $_SERVER['argv'] = [];
         $config          = new ConfigDouble();
@@ -67,20 +65,15 @@ public static function initializeFile()
         self::$phpcsFile = new DummyFile($contents, $ruleset, $config);
         self::$phpcsFile->parse();
 
-    }//end initializeFile()
+    }//end setUpBeforeClass()
 
 
     /**
      * Clean up after finished test by resetting all static properties on the class to their default values.
      *
-     * Note: This is a PHPUnit cross-version compatible {@see \PHPUnit\Framework\TestCase::tearDownAfterClass()}
-     * method.
-     *
-     * @afterClass
-     *
      * @return void
      */
-    public static function reset()
+    public static function tearDownAfterClass(): void
     {
         // Explicitly trigger __destruct() on the ConfigDouble to reset the Config statics.
         // The explicit method call prevents potential stray test-local references to the $config object
@@ -93,7 +86,7 @@ public static function reset()
         self::$tabWidth  = 4;
         self::$phpcsFile = null;
 
-    }//end reset()
+    }//end tearDownAfterClass()
 
 
     /**
@@ -246,16 +239,8 @@ public static function getTargetTokenFromFile(File $phpcsFile, $commentString, $
      */
     public function expectRunTimeException($message)
     {
-        $exception = 'PHP_CodeSniffer\Exceptions\RuntimeException';
-
-        if (method_exists($this, 'expectException') === true) {
-            // PHPUnit 5+.
-            $this->expectException($exception);
-            $this->expectExceptionMessage($message);
-        } else {
-            // PHPUnit 4.
-            $this->setExpectedException($exception, $message);
-        }
+        $this->expectException('PHP_CodeSniffer\Exceptions\RuntimeException');
+        $this->expectExceptionMessage($message);
 
     }//end expectRunTimeException()
 
diff --git a/tests/Core/Autoloader/DetermineLoadedClassTest.php b/tests/Core/Autoloader/DetermineLoadedClassTest.php
index e719c7eb74..c2dffde79d 100644
--- a/tests/Core/Autoloader/DetermineLoadedClassTest.php
+++ b/tests/Core/Autoloader/DetermineLoadedClassTest.php
@@ -24,15 +24,13 @@ final class DetermineLoadedClassTest extends TestCase
     /**
      * Load the test files.
      *
-     * @beforeClass
-     *
      * @return void
      */
-    public static function includeFixture()
+    public static function setUpBeforeClass(): void
     {
         include __DIR__.'/TestFiles/Sub/C.inc';
 
-    }//end includeFixture()
+    }//end setUpBeforeClass()
 
 
     /**
diff --git a/tests/Core/Config/AbstractRealConfigTestCase.php b/tests/Core/Config/AbstractRealConfigTestCase.php
index 6f5cd88443..e1a7975d4d 100644
--- a/tests/Core/Config/AbstractRealConfigTestCase.php
+++ b/tests/Core/Config/AbstractRealConfigTestCase.php
@@ -20,11 +20,9 @@ abstract class AbstractRealConfigTestCase extends TestCase
     /**
      * Set static properties in the Config class to prevent tests influencing each other.
      *
-     * @before
-     *
      * @return void
      */
-    protected function setConfigStatics()
+    protected function setUp(): void
     {
         // Set to the property's default value to clear out potentially set values from other tests.
         self::setStaticConfigProperty('overriddenDefaults', []);
@@ -35,32 +33,28 @@ protected function setConfigStatics()
         self::setStaticConfigProperty('configData', []);
         self::setStaticConfigProperty('configDataFile', '');
 
-    }//end setConfigStatics()
+    }//end setUp()
 
 
     /**
      * Clean up after each finished test.
      *
-     * @after
-     *
      * @return void
      */
-    protected function clearArgv()
+    protected function tearDown(): void
     {
         $_SERVER['argv'] = [];
 
-    }//end clearArgv()
+    }//end tearDown()
 
 
     /**
      * Reset the static properties in the Config class to their true defaults to prevent this class
      * from influencing other tests.
      *
-     * @afterClass
-     *
      * @return void
      */
-    public static function resetConfigToDefaults()
+    public static function tearDownAfterClass(): void
     {
         self::setStaticConfigProperty('overriddenDefaults', []);
         self::setStaticConfigProperty('executablePaths', []);
@@ -68,7 +62,7 @@ public static function resetConfigToDefaults()
         self::setStaticConfigProperty('configDataFile', null);
         $_SERVER['argv'] = [];
 
-    }//end resetConfigToDefaults()
+    }//end tearDownAfterClass()
 
 
     /**
diff --git a/tests/Core/Config/GeneratorArgTest.php b/tests/Core/Config/GeneratorArgTest.php
index 5def5f68f8..16135549f1 100644
--- a/tests/Core/Config/GeneratorArgTest.php
+++ b/tests/Core/Config/GeneratorArgTest.php
@@ -112,14 +112,8 @@ public function testInvalidGenerator($generatorName)
         $exception = 'PHP_CodeSniffer\Exceptions\DeepExitException';
         $message   = 'ERROR: "'.$generatorName.'" is not a valid generator. The following generators are supported: Text, HTML and Markdown.';
 
-        if (method_exists($this, 'expectException') === true) {
-            // PHPUnit 5+.
-            $this->expectException($exception);
-            $this->expectExceptionMessage($message);
-        } else {
-            // PHPUnit 4.
-            $this->setExpectedException($exception, $message);
-        }
+        $this->expectException($exception);
+        $this->expectExceptionMessage($message);
 
         new ConfigDouble(["--generator={$generatorName}"]);
 
diff --git a/tests/Core/Config/ReportWidthTest.php b/tests/Core/Config/ReportWidthTest.php
index 28b996228d..71e20a9549 100644
--- a/tests/Core/Config/ReportWidthTest.php
+++ b/tests/Core/Config/ReportWidthTest.php
@@ -34,7 +34,7 @@ public function testReportWidthDefault()
         $config = new Config(['--standard=PSR1']);
 
         // Can't test the exact value as "auto" will resolve differently depending on the machine running the tests.
-        $this->assertTrue(is_int($config->reportWidth), 'Report width is not an integer');
+        $this->assertIsInt($config->reportWidth, 'Report width is not an integer');
         $this->assertGreaterThan(0, $config->reportWidth, 'Report width is not greater than 0');
 
     }//end testReportWidthDefault()
@@ -60,7 +60,7 @@ public function testReportWidthWillBeSetFromAutoWhenNotFoundInConfFile()
         $config = new Config(['--standard=PSR1']);
 
         // Can't test the exact value as "auto" will resolve differently depending on the machine running the tests.
-        $this->assertTrue(is_int($config->reportWidth), 'Report width is not an integer');
+        $this->assertIsInt($config->reportWidth, 'Report width is not an integer');
         $this->assertGreaterThan(0, $config->reportWidth, 'Report width is not greater than 0');
 
     }//end testReportWidthWillBeSetFromAutoWhenNotFoundInConfFile()
@@ -181,7 +181,7 @@ public function testReportWidthInputHandlingForAuto()
         $config->reportWidth = 'auto';
 
         // Can't test the exact value as "auto" will resolve differently depending on the machine running the tests.
-        $this->assertTrue(is_int($config->reportWidth), 'Report width is not an integer');
+        $this->assertIsInt($config->reportWidth, 'Report width is not an integer');
         $this->assertGreaterThan(0, $config->reportWidth, 'Report width is not greater than 0');
 
     }//end testReportWidthInputHandlingForAuto()
diff --git a/tests/Core/Config/SniffsExcludeArgsTest.php b/tests/Core/Config/SniffsExcludeArgsTest.php
index 59aabecc19..26bc7ebeb2 100644
--- a/tests/Core/Config/SniffsExcludeArgsTest.php
+++ b/tests/Core/Config/SniffsExcludeArgsTest.php
@@ -50,14 +50,8 @@ public function testInvalid($argument, $value, $errors, $suggestion)
         $message .= 'Run "phpcs --help" for usage information'.PHP_EOL;
         $message .= PHP_EOL;
 
-        if (method_exists($this, 'expectException') === true) {
-            // PHPUnit 5+.
-            $this->expectException($exception);
-            $this->expectExceptionMessage($message);
-        } else {
-            // PHPUnit 4.
-            $this->setExpectedException($exception, $message);
-        }
+        $this->expectException($exception);
+        $this->expectExceptionMessage($message);
 
         new ConfigDouble(["--$argument=$value"]);
 
diff --git a/tests/Core/File/GetConditionTest.php b/tests/Core/File/GetConditionTest.php
index 1f9d9a3454..c53a280b3a 100644
--- a/tests/Core/File/GetConditionTest.php
+++ b/tests/Core/File/GetConditionTest.php
@@ -123,11 +123,9 @@ final class GetConditionTest extends AbstractMethodUnitTest
      * Retrieves the test tokens and marker token stack pointer positions
      * only once and caches them as they won't change between the tests anyway.
      *
-     * @before
-     *
      * @return void
      */
-    protected function setUpCaches()
+    protected function setUp(): void
     {
         if (empty(self::$testTokens) === true) {
             foreach (self::$testTargets as $targetToken => $marker) {
@@ -141,7 +139,7 @@ protected function setUpCaches()
             }
         }
 
-    }//end setUpCaches()
+    }//end setUp()
 
 
     /**
diff --git a/tests/Core/Filters/AbstractFilterTestCase.php b/tests/Core/Filters/AbstractFilterTestCase.php
index 1087a22623..f95a51c0c7 100644
--- a/tests/Core/Filters/AbstractFilterTestCase.php
+++ b/tests/Core/Filters/AbstractFilterTestCase.php
@@ -39,29 +39,22 @@ abstract class AbstractFilterTestCase extends TestCase
     /**
      * Initialize the config and ruleset objects.
      *
-     * @beforeClass
-     *
      * @return void
      */
-    public static function initializeConfigAndRuleset()
+    public static function setUpBeforeClass(): void
     {
         self::$config  = new ConfigDouble();
         self::$ruleset = new Ruleset(self::$config);
 
-    }//end initializeConfigAndRuleset()
+    }//end setUpBeforeClass()
 
 
     /**
      * Clean up after finished test by resetting all static properties on the Config class to their default values.
      *
-     * Note: This is a PHPUnit cross-version compatible {@see \PHPUnit\Framework\TestCase::tearDownAfterClass()}
-     * method.
-     *
-     * @afterClass
-     *
      * @return void
      */
-    public static function reset()
+    public static function tearDownAfterClass(): void
     {
         // Explicitly trigger __destruct() on the ConfigDouble to reset the Config statics.
         // The explicit method call prevents potential stray test-local references to the $config object
@@ -71,7 +64,7 @@ public static function reset()
             self::$config->__destruct();
         }
 
-    }//end reset()
+    }//end tearDownAfterClass()
 
 
     /**
@@ -96,24 +89,15 @@ protected function getMockedClass($className, array $constructorArgs=[], $method
     {
         $mockedObj = $this->getMockBuilder($className);
 
-        if (method_exists($mockedObj, 'onlyMethods') === true) {
-            // PHPUnit 8+.
-            if (is_array($methodsToMock) === true) {
-                return $mockedObj
-                    ->setConstructorArgs($constructorArgs)
-                    ->onlyMethods($methodsToMock)
-                    ->getMock();
-            }
-
-            return $mockedObj->getMock()
-                ->setConstructorArgs($constructorArgs);
+        if (is_array($methodsToMock) === true) {
+            return $mockedObj
+                ->setConstructorArgs($constructorArgs)
+                ->onlyMethods($methodsToMock)
+                ->getMock();
         }
 
-        // PHPUnit < 8.
-        return $mockedObj
-            ->setConstructorArgs($constructorArgs)
-            ->setMethods($methodsToMock)
-            ->getMock();
+        return $mockedObj->getMock()
+            ->setConstructorArgs($constructorArgs);
 
     }//end getMockedClass()
 
diff --git a/tests/Core/Filters/Filter/AcceptTest.php b/tests/Core/Filters/Filter/AcceptTest.php
index d4da0a248c..f0723c134b 100644
--- a/tests/Core/Filters/Filter/AcceptTest.php
+++ b/tests/Core/Filters/Filter/AcceptTest.php
@@ -28,17 +28,15 @@ final class AcceptTest extends AbstractFilterTestCase
     /**
      * Initialize the config and ruleset objects based on the `AcceptTest.xml` ruleset file.
      *
-     * @beforeClass
-     *
      * @return void
      */
-    public static function initializeConfigAndRuleset()
+    public static function setUpBeforeClass(): void
     {
         $standard      = __DIR__.'/'.basename(__FILE__, '.php').'.xml';
         self::$config  = new ConfigDouble(["--standard=$standard", '--ignore=*/somethingelse/*']);
         self::$ruleset = new Ruleset(self::$config);
 
-    }//end initializeConfigAndRuleset()
+    }//end setUpBeforeClass()
 
 
     /**
diff --git a/tests/Core/Fixer/GenerateDiffTest.php b/tests/Core/Fixer/GenerateDiffTest.php
index b7902bbe61..940584e52f 100644
--- a/tests/Core/Fixer/GenerateDiffTest.php
+++ b/tests/Core/Fixer/GenerateDiffTest.php
@@ -46,11 +46,9 @@ final class GenerateDiffTest extends TestCase
      * prevent doing tab replacement when parsing the file. This is to allow for testing a
      * diff with tabs vs spaces (which wouldn't yield a diff if tabs had already been replaced).
      *
-     * @beforeClass
-     *
      * @return void
      */
-    public static function initializeFile()
+    public static function setUpBeforeClass(): void
     {
         $config  = new ConfigDouble();
         $ruleset = new Ruleset($config);
@@ -59,7 +57,7 @@ public static function initializeFile()
         self::$phpcsFile->parse();
         self::$phpcsFile->fixer->startFile(self::$phpcsFile);
 
-    }//end initializeFile()
+    }//end setUpBeforeClass()
 
 
     /**
diff --git a/tests/Core/Generators/GeneratorTest.php b/tests/Core/Generators/GeneratorTest.php
index 8fb0ee2516..fb237b3a39 100644
--- a/tests/Core/Generators/GeneratorTest.php
+++ b/tests/Core/Generators/GeneratorTest.php
@@ -106,24 +106,13 @@ public function testGeneratingInvalidDocsResultsInException()
         $ruleset  = new Ruleset($config);
 
         if (PHP_VERSION_ID >= 80000) {
-            $exception = 'TypeError';
-            $message   = 'processSniff(): Argument #1 ($doc) must be of type DOMNode, null given';
-        } else if (PHP_VERSION_ID >= 70000) {
-            $exception = 'TypeError';
-            $message   = 'processSniff() must be an instance of DOMNode, null given';
+            $message = 'processSniff(): Argument #1 ($doc) must be of type DOMNode, null given';
         } else {
-            $exception = 'PHPUnit_Framework_Error';
-            $message   = 'processSniff() must be an instance of DOMNode, null given';
+            $message = 'processSniff() must be an instance of DOMNode, null given';
         }
 
-        if (method_exists($this, 'expectExceptionMessage') === true) {
-            // PHPUnit 5.2.0+.
-            $this->expectException($exception);
-            $this->expectExceptionMessage($message);
-        } else {
-            // Ancient PHPUnit.
-            $this->setExpectedException($exception, $message);
-        }
+        $this->expectException('TypeError');
+        $this->expectExceptionMessage($message);
 
         $generator = new MockGenerator($ruleset);
         $generator->generate();
diff --git a/tests/Core/Ruleset/AbstractRulesetTestCase.php b/tests/Core/Ruleset/AbstractRulesetTestCase.php
index 41c6394431..5b944bd25e 100644
--- a/tests/Core/Ruleset/AbstractRulesetTestCase.php
+++ b/tests/Core/Ruleset/AbstractRulesetTestCase.php
@@ -75,14 +75,8 @@ protected function assertXObjectNotHasProperty($propertyName, $object, $message=
      */
     protected function expectRuntimeExceptionMessage($message)
     {
-        if (method_exists($this, 'expectException') === true) {
-            // PHPUnit 5+.
-            $this->expectException(self::RUNTIME_EXCEPTION);
-            $this->expectExceptionMessage($message);
-        } else {
-            // PHPUnit 4.
-            $this->setExpectedException(self::RUNTIME_EXCEPTION, $message);
-        }
+        $this->expectException(self::RUNTIME_EXCEPTION);
+        $this->expectExceptionMessage($message);
 
     }//end expectRuntimeExceptionMessage()
 
@@ -100,13 +94,10 @@ protected function expectRuntimeExceptionRegex($regex)
         if (method_exists($this, 'expectExceptionMessageMatches') === true) {
             $this->expectException(self::RUNTIME_EXCEPTION);
             $this->expectExceptionMessageMatches($regex);
-        } else if (method_exists($this, 'expectExceptionMessageRegExp') === true) {
+        } else {
             // PHPUnit < 8.4.0.
             $this->expectException(self::RUNTIME_EXCEPTION);
             $this->expectExceptionMessageRegExp($regex);
-        } else {
-            // PHPUnit < 5.2.0.
-            $this->setExpectedExceptionRegExp(self::RUNTIME_EXCEPTION, $regex);
         }
 
     }//end expectRuntimeExceptionRegex()
diff --git a/tests/Core/Ruleset/ExpandRulesetReferenceHomePathTest.php b/tests/Core/Ruleset/ExpandRulesetReferenceHomePathTest.php
index 10a4dd9813..80fa9e0a03 100644
--- a/tests/Core/Ruleset/ExpandRulesetReferenceHomePathTest.php
+++ b/tests/Core/Ruleset/ExpandRulesetReferenceHomePathTest.php
@@ -32,25 +32,21 @@ final class ExpandRulesetReferenceHomePathTest extends AbstractRulesetTestCase
     /**
      * Store the user's home path.
      *
-     * @beforeClass
-     *
      * @return void
      */
-    public static function storeHomePath()
+    public static function setUpBeforeClass(): void
     {
         self::$homepath = getenv('HOME');
 
-    }//end storeHomePath()
+    }//end setUpBeforeClass()
 
 
     /**
      * Restore the user's home path environment variable in case the test changed it or created it.
      *
-     * @afterClass
-     *
      * @return void
      */
-    public static function restoreHomePath()
+    public static function tearDownAfterClass(): void
     {
         if (is_string(self::$homepath) === true) {
             putenv('HOME='.self::$homepath);
@@ -59,22 +55,20 @@ public static function restoreHomePath()
             putenv('HOME');
         }
 
-    }//end restoreHomePath()
+    }//end tearDownAfterClass()
 
 
     /**
      * Set the home path to an alternative location.
      *
-     * @before
-     *
      * @return void
      */
-    protected function setHomePath()
+    protected function setUp(): void
     {
         $fakeHomePath = __DIR__.DIRECTORY_SEPARATOR.'Fixtures'.DIRECTORY_SEPARATOR.'FakeHomePath';
         putenv("HOME=$fakeHomePath");
 
-    }//end setHomePath()
+    }//end setUp()
 
 
     /**
diff --git a/tests/Core/Ruleset/GetIgnorePatternsTest.php b/tests/Core/Ruleset/GetIgnorePatternsTest.php
index ae6b8bea50..23fe0532c9 100644
--- a/tests/Core/Ruleset/GetIgnorePatternsTest.php
+++ b/tests/Core/Ruleset/GetIgnorePatternsTest.php
@@ -32,18 +32,16 @@ final class GetIgnorePatternsTest extends TestCase
     /**
      * Initialize the config and ruleset objects for this test.
      *
-     * @beforeClass
-     *
      * @return void
      */
-    public static function initializeConfigAndRuleset()
+    public static function setUpBeforeClass(): void
     {
         // Set up the ruleset.
         $standard      = __DIR__."/GetIgnorePatternsTest.xml";
         $config        = new ConfigDouble(["--standard=$standard"]);
         self::$ruleset = new Ruleset($config);
 
-    }//end initializeConfigAndRuleset()
+    }//end setUpBeforeClass()
 
 
     /**
diff --git a/tests/Core/Ruleset/GetIncludePatternsTest.php b/tests/Core/Ruleset/GetIncludePatternsTest.php
index a38401b614..b67c189e11 100644
--- a/tests/Core/Ruleset/GetIncludePatternsTest.php
+++ b/tests/Core/Ruleset/GetIncludePatternsTest.php
@@ -32,18 +32,16 @@ final class GetIncludePatternsTest extends TestCase
     /**
      * Initialize the config and ruleset objects for this test.
      *
-     * @beforeClass
-     *
      * @return void
      */
-    public static function initializeConfigAndRuleset()
+    public static function setUpBeforeClass(): void
     {
         // Set up the ruleset.
         $standard      = __DIR__."/GetIncludePatternsTest.xml";
         $config        = new ConfigDouble(["--standard=$standard"]);
         self::$ruleset = new Ruleset($config);
 
-    }//end initializeConfigAndRuleset()
+    }//end setUpBeforeClass()
 
 
     /**
diff --git a/tests/Core/Ruleset/PopulateTokenListenersTest.php b/tests/Core/Ruleset/PopulateTokenListenersTest.php
index db494b9590..68a30e3a4b 100644
--- a/tests/Core/Ruleset/PopulateTokenListenersTest.php
+++ b/tests/Core/Ruleset/PopulateTokenListenersTest.php
@@ -35,11 +35,9 @@ final class PopulateTokenListenersTest extends AbstractRulesetTestCase
     /**
      * Initialize the config and ruleset objects for this test only once (but do allow recording code coverage).
      *
-     * @before
-     *
      * @return void
      */
-    protected function initializeConfigAndRuleset()
+    protected function setUp(): void
     {
         if (isset(self::$ruleset) === false) {
             // Set up the ruleset.
@@ -48,7 +46,7 @@ protected function initializeConfigAndRuleset()
             self::$ruleset = new Ruleset($config);
         }
 
-    }//end initializeConfigAndRuleset()
+    }//end setUp()
 
 
     /**
@@ -85,7 +83,7 @@ public function testSniffWithRegisterMethodReturningEmptyArrayIsSilentlyIgnored(
         $target = 'Fixtures\\TestStandard\\Sniffs\\ValidSniffs\\RegisterEmptyArraySniff';
 
         foreach (self::$ruleset->tokenListeners as $token => $listeners) {
-            $this->assertTrue(is_array($listeners), 'No listeners registered for token'.Tokens::tokenName($token));
+            $this->assertIsArray($listeners, 'No listeners registered for token'.Tokens::tokenName($token));
             $this->assertArrayNotHasKey(
                 $target,
                 $listeners,
@@ -174,7 +172,7 @@ public function testRegistersWhenADeprecatedSniffIsLoaded()
 
         // Only verify there is one deprecated sniff registered.
         // There are other tests which test the deprecated sniff handling in more detail.
-        $this->assertTrue(is_array($actualValue));
+        $this->assertIsArray($actualValue);
         $this->assertCount(1, $actualValue);
 
     }//end testRegistersWhenADeprecatedSniffIsLoaded()
@@ -263,7 +261,7 @@ public static function dataTriggersPropertySettingWhenPropertiesProvided()
     public function testSetsClassAndSourceIndexes()
     {
         foreach (self::$ruleset->tokenListeners as $token => $listeners) {
-            $this->assertTrue(is_array($listeners), 'No listeners registered for token'.Tokens::tokenName($token));
+            $this->assertIsArray($listeners, 'No listeners registered for token'.Tokens::tokenName($token));
 
             foreach ($listeners as $className => $details) {
                 $this->assertArrayHasKey(
@@ -284,8 +282,8 @@ public function testSetsClassAndSourceIndexes()
                     sprintf('"source" key missing for sniff class %s for token %s', $className, Tokens::tokenName($token))
                 );
 
-                $this->assertTrue(
-                    is_string($details['source']),
+                $this->assertIsString(
+                    $details['source'],
                     sprintf('Value for "source" key is not a string for token %s', Tokens::tokenName($token))
                 );
 
@@ -312,7 +310,7 @@ public function testSetsIncludePatternsToEmptyArrayByDefault()
         $exclude = 'PHP_CodeSniffer\\Standards\\Generic\\Sniffs\\NamingConventions\\UpperCaseConstantNameSniff';
 
         foreach (self::$ruleset->tokenListeners as $token => $listeners) {
-            $this->assertTrue(is_array($listeners), 'No listeners registered for token'.Tokens::tokenName($token));
+            $this->assertIsArray($listeners, 'No listeners registered for token'.Tokens::tokenName($token));
 
             foreach ($listeners as $className => $details) {
                 if ($className === $exclude) {
@@ -347,7 +345,7 @@ public function testSetsIgnorePatternsToEmptyArrayByDefault()
         $exclude = 'PHP_CodeSniffer\\Standards\\PSR1\\Sniffs\\Files\\SideEffectsSniff';
 
         foreach (self::$ruleset->tokenListeners as $token => $listeners) {
-            $this->assertTrue(is_array($listeners), 'No listeners registered for token'.Tokens::tokenName($token));
+            $this->assertIsArray($listeners, 'No listeners registered for token'.Tokens::tokenName($token));
 
             foreach ($listeners as $className => $details) {
                 if ($className === $exclude) {
diff --git a/tests/Core/Ruleset/ProcessRuleShouldProcessElementTest.php b/tests/Core/Ruleset/ProcessRuleShouldProcessElementTest.php
index c6c9e2160b..2ec67a9e46 100644
--- a/tests/Core/Ruleset/ProcessRuleShouldProcessElementTest.php
+++ b/tests/Core/Ruleset/ProcessRuleShouldProcessElementTest.php
@@ -33,11 +33,9 @@ final class ProcessRuleShouldProcessElementTest extends AbstractRulesetTestCase
     /**
      * Initialize the config and ruleset objects for this test.
      *
-     * @before
-     *
      * @return void
      */
-    protected function initializeConfigAndRuleset()
+    protected function setUp(): void
     {
         if (isset(self::$ruleset) === false) {
             // Set up the ruleset.
@@ -46,7 +44,7 @@ protected function initializeConfigAndRuleset()
             self::$ruleset = new Ruleset($config);
         }
 
-    }//end initializeConfigAndRuleset()
+    }//end setUp()
 
 
     /**
@@ -618,7 +616,7 @@ private function verifyShouldProcessElement($expected)
     private function assertHasRulesetDirective($sniffCode, $key)
     {
         $this->assertArrayHasKey($sniffCode, self::$ruleset->ruleset, "Sniff $sniffCode not registered");
-        $this->assertTrue(is_array(self::$ruleset->ruleset[$sniffCode]), "Sniff $sniffCode is not an array");
+        $this->assertIsArray(self::$ruleset->ruleset[$sniffCode], "Sniff $sniffCode is not an array");
         $this->assertArrayHasKey($key, self::$ruleset->ruleset[$sniffCode], "Directive $key not registered for sniff $sniffCode");
 
     }//end assertHasRulesetDirective()
diff --git a/tests/Core/Ruleset/ProcessRulesetShouldProcessElementTest.php b/tests/Core/Ruleset/ProcessRulesetShouldProcessElementTest.php
index 1f0780c44b..59ab1d675e 100644
--- a/tests/Core/Ruleset/ProcessRulesetShouldProcessElementTest.php
+++ b/tests/Core/Ruleset/ProcessRulesetShouldProcessElementTest.php
@@ -52,11 +52,9 @@ final class ProcessRulesetShouldProcessElementTest extends TestCase
     /**
      * Store the original ini values to allow for restoring them after the tests.
      *
-     * @beforeClass
-     *
      * @return void
      */
-    public static function saveOriginalIniValues()
+    public static function setUpBeforeClass(): void
     {
         foreach (self::$originalIniValues as $name => $null) {
             $value = ini_get($name);
@@ -65,17 +63,15 @@ public static function saveOriginalIniValues()
             }
         }
 
-    }//end saveOriginalIniValues()
+    }//end setUpBeforeClass()
 
 
     /**
      * Initialize the config and ruleset objects for this test only once (but do allow recording code coverage).
      *
-     * @before
-     *
      * @return void
      */
-    protected function initializeConfigAndRuleset()
+    protected function setUp(): void
     {
         if (isset(self::$ruleset) === false) {
             // Set up the ruleset.
@@ -84,17 +80,15 @@ protected function initializeConfigAndRuleset()
             self::$ruleset = new Ruleset(self::$config);
         }
 
-    }//end initializeConfigAndRuleset()
+    }//end setUp()
 
 
     /**
      * Destroy the Config object and restore the ini values after the tests.
      *
-     * @afterClass
-     *
      * @return void
      */
-    public static function restoreOriginalValues()
+    public static function tearDownAfterClass(): void
     {
         // Explicitly trigger __destruct() on the ConfigDouble to reset the Config statics.
         // The explicit method call prevents potential stray test-local references to the $config object
@@ -112,7 +106,7 @@ public static function restoreOriginalValues()
             ini_set($name, $value);
         }
 
-    }//end restoreOriginalValues()
+    }//end tearDownAfterClass()
 
 
     /**
diff --git a/tests/Core/Ruleset/ProcessRulesetTest.php b/tests/Core/Ruleset/ProcessRulesetTest.php
index 3ef1f67688..2e5f705bde 100644
--- a/tests/Core/Ruleset/ProcessRulesetTest.php
+++ b/tests/Core/Ruleset/ProcessRulesetTest.php
@@ -159,13 +159,13 @@ public function testIncludeSingleErrorCode()
 
         $sniffCode = 'Generic.PHP.RequireStrictTypes';
         $this->assertArrayHasKey($sniffCode, $ruleset->ruleset, "Sniff $sniffCode not registered");
-        $this->assertTrue(is_array($ruleset->ruleset[$sniffCode]), "Sniff $sniffCode is not an array");
+        $this->assertIsArray($ruleset->ruleset[$sniffCode], "Sniff $sniffCode is not an array");
         $this->assertArrayHasKey($key, $ruleset->ruleset[$sniffCode], "Directive $key not registered for sniff $sniffCode");
         $this->assertSame(0, $ruleset->ruleset[$sniffCode][$key], "$key has unexpected value for sniff $sniffCode");
 
         $sniffCode = 'Generic.PHP.RequireStrictTypes.MissingDeclaration';
         $this->assertArrayHasKey($sniffCode, $ruleset->ruleset, "Sniff $sniffCode not registered");
-        $this->assertTrue(is_array($ruleset->ruleset[$sniffCode]), "Sniff $sniffCode is not an array");
+        $this->assertIsArray($ruleset->ruleset[$sniffCode], "Sniff $sniffCode is not an array");
         $this->assertArrayHasKey($key, $ruleset->ruleset[$sniffCode], "Directive $key not registered for sniff $sniffCode");
         $this->assertSame(5, $ruleset->ruleset[$sniffCode][$key], "$key has unexpected value for sniff $sniffCode");
 
@@ -187,19 +187,19 @@ public function testErrorCodeIncludeAfterExclude()
 
         $sniffCode = 'PEAR.Files.IncludingFile';
         $this->assertArrayHasKey($sniffCode, $ruleset->ruleset, "Sniff $sniffCode not registered");
-        $this->assertTrue(is_array($ruleset->ruleset[$sniffCode]), "Sniff $sniffCode is not an array");
+        $this->assertIsArray($ruleset->ruleset[$sniffCode], "Sniff $sniffCode is not an array");
         $this->assertArrayHasKey($key, $ruleset->ruleset[$sniffCode], "Directive $key not registered for sniff $sniffCode");
         $this->assertSame(0, $ruleset->ruleset[$sniffCode][$key], "$key has unexpected value for sniff $sniffCode");
 
         $sniffCode = 'PEAR.Files.IncludingFile.BracketsNotRequired';
         $this->assertArrayHasKey($sniffCode, $ruleset->ruleset, "Sniff $sniffCode not registered");
-        $this->assertTrue(is_array($ruleset->ruleset[$sniffCode]), "Sniff $sniffCode is not an array");
+        $this->assertIsArray($ruleset->ruleset[$sniffCode], "Sniff $sniffCode is not an array");
         $this->assertArrayHasKey($key, $ruleset->ruleset[$sniffCode], "Directive $key not registered for sniff $sniffCode");
         $this->assertSame(5, $ruleset->ruleset[$sniffCode][$key], "$key has unexpected value for sniff $sniffCode");
 
         $sniffCode = 'PEAR.Files.IncludingFile.UseRequire';
         $this->assertArrayHasKey($sniffCode, $ruleset->ruleset, "Sniff $sniffCode not registered");
-        $this->assertTrue(is_array($ruleset->ruleset[$sniffCode]), "Sniff $sniffCode is not an array");
+        $this->assertIsArray($ruleset->ruleset[$sniffCode], "Sniff $sniffCode is not an array");
         $this->assertArrayHasKey($key, $ruleset->ruleset[$sniffCode], "Directive $key not registered for sniff $sniffCode");
         $this->assertSame(5, $ruleset->ruleset[$sniffCode][$key], "$key has unexpected value for sniff $sniffCode");
 
diff --git a/tests/Core/Ruleset/RegisterSniffsRemovedTokenizersTest.php b/tests/Core/Ruleset/RegisterSniffsRemovedTokenizersTest.php
index 4d12bf43f7..9ffd0a6404 100644
--- a/tests/Core/Ruleset/RegisterSniffsRemovedTokenizersTest.php
+++ b/tests/Core/Ruleset/RegisterSniffsRemovedTokenizersTest.php
@@ -32,17 +32,15 @@ final class RegisterSniffsRemovedTokenizersTest extends AbstractRulesetTestCase
     /**
      * Initialize the config and ruleset objects for this test.
      *
-     * @beforeClass
-     *
      * @return void
      */
-    public static function initializeConfig()
+    public static function setUpBeforeClass(): void
     {
         // Set up the ruleset.
         $standard     = __DIR__.'/RegisterSniffsRemovedTokenizersTest.xml';
         self::$config = new ConfigDouble(["--standard=$standard"]);
 
-    }//end initializeConfig()
+    }//end setUpBeforeClass()
 
 
     /**
diff --git a/tests/Core/Ruleset/RegisterSniffsTest.php b/tests/Core/Ruleset/RegisterSniffsTest.php
index 1ed3ee1821..37fe2b500d 100644
--- a/tests/Core/Ruleset/RegisterSniffsTest.php
+++ b/tests/Core/Ruleset/RegisterSniffsTest.php
@@ -62,11 +62,9 @@ final class RegisterSniffsTest extends TestCase
     /**
      * Initialize the config and ruleset objects which will be used for some of these tests.
      *
-     * @beforeClass
-     *
      * @return void
      */
-    public static function initializeConfigAndRuleset()
+    public static function setUpBeforeClass(): void
     {
         // Set up the ruleset.
         $config        = new ConfigDouble(['--standard=PSR1']);
@@ -85,7 +83,7 @@ public static function initializeConfigAndRuleset()
 
         self::$psr1SniffAbsolutePaths = self::relativeToAbsoluteSniffFiles($standardsDir, self::$psr1SniffFiles);
 
-    }//end initializeConfigAndRuleset()
+    }//end setUpBeforeClass()
 
 
     /**
@@ -113,16 +111,14 @@ public static function relativeToAbsoluteSniffFiles($baseDir, $relativePaths)
     /**
      * Clear out the Ruleset::$sniffs property.
      *
-     * @before
-     *
      * @return void
      */
-    protected function clearOutSniffs()
+    protected function setUp(): void
     {
         // Clear out the Ruleset::$sniffs property.
         self::$ruleset->sniffs = [];
 
-    }//end clearOutSniffs()
+    }//end setUp()
 
 
     /**
diff --git a/tests/Core/Ruleset/RuleInclusionAbsoluteLinuxTest.php b/tests/Core/Ruleset/RuleInclusionAbsoluteLinuxTest.php
index 6eb0d1a208..80eb4b7ae9 100644
--- a/tests/Core/Ruleset/RuleInclusionAbsoluteLinuxTest.php
+++ b/tests/Core/Ruleset/RuleInclusionAbsoluteLinuxTest.php
@@ -46,11 +46,9 @@ final class RuleInclusionAbsoluteLinuxTest extends TestCase
     /**
      * Initialize the config and ruleset objects.
      *
-     * @before
-     *
      * @return void
      */
-    protected function initializeConfigAndRuleset()
+    protected function setUp(): void
     {
         $this->standard = __DIR__.'/'.basename(__FILE__, '.php').'.xml';
         $repoRootDir    = dirname(dirname(dirname(__DIR__)));
@@ -74,21 +72,19 @@ protected function initializeConfigAndRuleset()
         $config        = new ConfigDouble(["--standard={$this->standard}"]);
         $this->ruleset = new Ruleset($config);
 
-    }//end initializeConfigAndRuleset()
+    }//end setUp()
 
 
     /**
      * Reset ruleset file.
      *
-     * @after
-     *
      * @return void
      */
-    protected function resetRuleset()
+    protected function tearDown(): void
     {
         file_put_contents($this->standard, $this->contents);
 
-    }//end resetRuleset()
+    }//end tearDown()
 
 
     /**
diff --git a/tests/Core/Ruleset/RuleInclusionAbsoluteWindowsTest.php b/tests/Core/Ruleset/RuleInclusionAbsoluteWindowsTest.php
index fc5d654885..73647cad0c 100644
--- a/tests/Core/Ruleset/RuleInclusionAbsoluteWindowsTest.php
+++ b/tests/Core/Ruleset/RuleInclusionAbsoluteWindowsTest.php
@@ -17,7 +17,7 @@
  * Tests for the \PHP_CodeSniffer\Ruleset class using a Windows-style absolute path to include a sniff.
  *
  * @covers   \PHP_CodeSniffer\Ruleset
- * @requires OS ^WIN.*.
+ * @requires OSFAMILY Windows
  * @group    Windows
  */
 final class RuleInclusionAbsoluteWindowsTest extends TestCase
@@ -48,11 +48,9 @@ final class RuleInclusionAbsoluteWindowsTest extends TestCase
     /**
      * Initialize the config and ruleset objects.
      *
-     * @before
-     *
      * @return void
      */
-    protected function initializeConfigAndRuleset()
+    protected function setUp(): void
     {
         $this->standard = __DIR__.'/'.basename(__FILE__, '.php').'.xml';
         $repoRootDir    = dirname(dirname(dirname(__DIR__)));
@@ -71,21 +69,19 @@ protected function initializeConfigAndRuleset()
         $config        = new ConfigDouble(["--standard={$this->standard}"]);
         $this->ruleset = new Ruleset($config);
 
-    }//end initializeConfigAndRuleset()
+    }//end setUp()
 
 
     /**
      * Reset ruleset file.
      *
-     * @after
-     *
      * @return void
      */
-    protected function resetRuleset()
+    protected function tearDown(): void
     {
         file_put_contents($this->standard, $this->contents);
 
-    }//end resetRuleset()
+    }//end tearDown()
 
 
     /**
diff --git a/tests/Core/Ruleset/RuleInclusionTest.php b/tests/Core/Ruleset/RuleInclusionTest.php
index d91a6c2590..9c31d1b79a 100644
--- a/tests/Core/Ruleset/RuleInclusionTest.php
+++ b/tests/Core/Ruleset/RuleInclusionTest.php
@@ -46,11 +46,9 @@ final class RuleInclusionTest extends AbstractRulesetTestCase
     /**
      * Initialize the config and ruleset objects based on the `RuleInclusionTest.xml` ruleset file.
      *
-     * @before
-     *
      * @return void
      */
-    protected function initializeConfigAndRuleset()
+    protected function setUp(): void
     {
         if (self::$standard === '') {
             $standard       = __DIR__.'/'.basename(__FILE__, '.php').'.xml';
@@ -78,21 +76,19 @@ protected function initializeConfigAndRuleset()
             self::$ruleset = new Ruleset($config);
         }//end if
 
-    }//end initializeConfigAndRuleset()
+    }//end setUp()
 
 
     /**
      * Reset ruleset file.
      *
-     * @after
-     *
      * @return void
      */
-    public function resetRuleset()
+    public function tearDown(): void
     {
         file_put_contents(self::$standard, self::$contents);
 
-    }//end resetRuleset()
+    }//end tearDown()
 
 
     /**
diff --git a/tests/Core/Runner/PrintProgressTest.php b/tests/Core/Runner/PrintProgressTest.php
index 93535417e0..82ab98fa7d 100644
--- a/tests/Core/Runner/PrintProgressTest.php
+++ b/tests/Core/Runner/PrintProgressTest.php
@@ -54,11 +54,9 @@ final class PrintProgressTest extends TestCase
     /**
      * Create some re-usable objects for use in the tests.
      *
-     * @beforeClass
-     *
      * @return void
      */
-    public static function initializeConfigRulesetRunner()
+    public static function setUpBeforeClass(): void
     {
         self::$config            = new ConfigDouble(['-p']);
         self::$config->standards = ['Generic'];
@@ -73,32 +71,28 @@ public static function initializeConfigRulesetRunner()
         self::$fileWithoutErrorsOrWarnings = new DummyFile($content, self::$ruleset, self::$config);
         self::$fileWithoutErrorsOrWarnings->process();
 
-    }//end initializeConfigRulesetRunner()
+    }//end setUpBeforeClass()
 
 
     /**
      * Reset some flags between tests.
      *
-     * @after
-     *
      * @return void
      */
-    protected function resetObjectFlags()
+    protected function tearDown(): void
     {
         self::$config->showProgress = true;
         self::$fileWithoutErrorsOrWarnings->ignored = false;
 
-    }//end resetObjectFlags()
+    }//end tearDown()
 
 
     /**
      * Destroy the Config object after the test to reset statics.
      *
-     * @afterClass
-     *
      * @return void
      */
-    public static function reset()
+    public static function tearDownAfterClass(): void
     {
         // Explicitly trigger __destruct() on the ConfigDouble to reset the Config statics.
         // The explicit method call prevents potential stray test-local references to the $config object
@@ -106,7 +100,7 @@ public static function reset()
         // automagically triggered when this object is destroyed, but we can't definitively rely on that).
         self::$config->__destruct();
 
-    }//end reset()
+    }//end tearDownAfterClass()
 
 
     /**
diff --git a/tests/Core/Sniffs/AbstractArraySniffTest.php b/tests/Core/Sniffs/AbstractArraySniffTest.php
index 993603a53b..d5a6f501e6 100644
--- a/tests/Core/Sniffs/AbstractArraySniffTest.php
+++ b/tests/Core/Sniffs/AbstractArraySniffTest.php
@@ -36,16 +36,14 @@ final class AbstractArraySniffTest extends AbstractMethodUnitTest
      * The test case file for a unit test class has to be in the same directory
      * directory and use the same file name as the test class, using the .inc extension.
      *
-     * @beforeClass
-     *
      * @return void
      */
-    public static function initializeFile()
+    public static function setUpBeforeClass(): void
     {
         self::$sniff = new AbstractArraySniffTestable();
-        parent::initializeFile();
+        parent::setUpBeforeClass();
 
-    }//end initializeFile()
+    }//end setUpBeforeClass()
 
 
     /**
diff --git a/tests/Core/Tokenizers/AbstractTokenizerTestCase.php b/tests/Core/Tokenizers/AbstractTokenizerTestCase.php
index ac9f8e3e9f..4c1fb1a8a3 100644
--- a/tests/Core/Tokenizers/AbstractTokenizerTestCase.php
+++ b/tests/Core/Tokenizers/AbstractTokenizerTestCase.php
@@ -45,11 +45,9 @@ abstract class AbstractTokenizerTestCase extends TestCase
      * The test case file for a unit test class has to be in the same directory
      * directory and use the same file name as the test class, using the .inc extension.
      *
-     * @before
-     *
      * @return void
      */
-    protected function initializeFile()
+    protected function setUp(): void
     {
         if (isset($this->phpcsFile) === false) {
             $_SERVER['argv'] = [];
@@ -73,7 +71,7 @@ protected function initializeFile()
             $this->phpcsFile->parse();
         }//end if
 
-    }//end initializeFile()
+    }//end setUp()
 
 
     /**
diff --git a/tests/Core/Tokenizers/PHP/GotoLabelTest.php b/tests/Core/Tokenizers/PHP/GotoLabelTest.php
index 09bb6fe2fd..93be957e13 100644
--- a/tests/Core/Tokenizers/PHP/GotoLabelTest.php
+++ b/tests/Core/Tokenizers/PHP/GotoLabelTest.php
@@ -36,7 +36,7 @@ public function testGotoStatement($testMarker, $testContent)
 
         $label = $this->getTargetToken($testMarker, T_STRING);
 
-        $this->assertTrue(is_int($label));
+        $this->assertIsInt($label);
         $this->assertSame($testContent, $tokens[$label]['content']);
 
     }//end testGotoStatement()
@@ -89,7 +89,7 @@ public function testGotoDeclaration($testMarker, $testContent)
 
         $label = $this->getTargetToken($testMarker, T_GOTO_LABEL);
 
-        $this->assertTrue(is_int($label));
+        $this->assertIsInt($label);
         $this->assertSame($testContent, $tokens[$label]['content']);
 
     }//end testGotoDeclaration()
diff --git a/tests/Core/Tokenizers/PHP/OtherContextSensitiveKeywordsTest.php b/tests/Core/Tokenizers/PHP/OtherContextSensitiveKeywordsTest.php
index 35c8997148..d49fcfaa16 100644
--- a/tests/Core/Tokenizers/PHP/OtherContextSensitiveKeywordsTest.php
+++ b/tests/Core/Tokenizers/PHP/OtherContextSensitiveKeywordsTest.php
@@ -25,15 +25,13 @@ final class OtherContextSensitiveKeywordsTest extends AbstractTokenizerTestCase
      * Clear the "resolved tokens" cache before running this test as otherwise the code
      * under test may not be run during the test.
      *
-     * @beforeClass
-     *
      * @return void
      */
-    public static function clearTokenCache()
+    public static function setUpBeforeClass(): void
     {
         parent::clearResolvedTokensCache();
 
-    }//end clearTokenCache()
+    }//end setUpBeforeClass()
 
 
     /**
diff --git a/tests/Core/Tokenizers/PHP/ResolveSimpleTokenTest.php b/tests/Core/Tokenizers/PHP/ResolveSimpleTokenTest.php
index 06a130c249..84ac47f5e1 100644
--- a/tests/Core/Tokenizers/PHP/ResolveSimpleTokenTest.php
+++ b/tests/Core/Tokenizers/PHP/ResolveSimpleTokenTest.php
@@ -25,15 +25,13 @@ final class ResolveSimpleTokenTest extends AbstractTokenizerTestCase
      * Clear the "resolved tokens" cache before running this test as otherwise the code
      * under test may not be run during the test.
      *
-     * @beforeClass
-     *
      * @return void
      */
-    public static function clearTokenCache()
+    public static function setUpBeforeClass(): void
     {
         parent::clearResolvedTokensCache();
 
-    }//end clearTokenCache()
+    }//end setUpBeforeClass()
 
 
     /**
diff --git a/tests/Core/Tokenizers/Tokenizer/ReplaceTabsInTokenMiscTest.php b/tests/Core/Tokenizers/Tokenizer/ReplaceTabsInTokenMiscTest.php
index f4bd711a6f..18b9ac548c 100644
--- a/tests/Core/Tokenizers/Tokenizer/ReplaceTabsInTokenMiscTest.php
+++ b/tests/Core/Tokenizers/Tokenizer/ReplaceTabsInTokenMiscTest.php
@@ -44,7 +44,7 @@ public function testTabWidthNotSet()
         $target = $phpcsFile->findNext(T_WHITESPACE, 0);
 
         // Verify initial state.
-        $this->assertTrue(is_int($target), 'Target token was not found');
+        $this->assertIsInt($target, 'Target token was not found');
         $this->assertSame('		', $tokens[$target]['content'], 'Content after initial parsing does not contain tabs');
         $this->assertSame(2, $tokens[$target]['length'], 'Length after initial parsing is not as expected');
         $this->assertArrayNotHasKey('orig_content', $tokens[$target], "Key 'orig_content' found in the initial token array.");
@@ -82,7 +82,7 @@ public function testLengthSettingRespectsEncoding()
         $tokens = $phpcsFile->getTokens();
         $target = $phpcsFile->findNext(T_CONSTANT_ENCAPSED_STRING, 0);
 
-        $this->assertTrue(is_int($target), 'Target token was not found');
+        $this->assertIsInt($target, 'Target token was not found');
         $this->assertSame("'пасха     пасха'", $tokens[$target]['content'], 'Content is not as expected');
         $this->assertSame(17, $tokens[$target]['length'], 'Length is not as expected');
         $this->assertArrayHasKey('orig_content', $tokens[$target], "Key 'orig_content' not found in the token array.");
@@ -114,7 +114,7 @@ public function testLengthSettingFallsBackToBytesWhenTextContainsIllegalChars()
         $tokens = $phpcsFile->getTokens();
         $target = $phpcsFile->findNext(T_CONSTANT_ENCAPSED_STRING, 0);
 
-        $this->assertTrue(is_int($target), 'Target token was not found');
+        $this->assertIsInt($target, 'Target token was not found');
         $this->assertSame(11, $tokens[$target]['length'], 'Length is not as expected');
         $this->assertArrayHasKey('orig_content', $tokens[$target], "Key 'orig_content' not found in the token array.");
 
diff --git a/tests/Core/Tokenizers/Tokenizer/ReplaceTabsInTokenTestCase.php b/tests/Core/Tokenizers/Tokenizer/ReplaceTabsInTokenTestCase.php
index 93964e1607..883c0779ee 100644
--- a/tests/Core/Tokenizers/Tokenizer/ReplaceTabsInTokenTestCase.php
+++ b/tests/Core/Tokenizers/Tokenizer/ReplaceTabsInTokenTestCase.php
@@ -31,13 +31,11 @@ abstract class ReplaceTabsInTokenTestCase extends AbstractTokenizerTestCase
     /**
      * Make a copy the test case file we want to use for this test (as the file will be used by multiple tests).
      *
-     * @beforeClass
-     *
      * @return void
      *
      * @throws \Exception In case the base test case file would not be available.
      */
-    public static function copyCaseFile()
+    public static function setUpBeforeClass(): void
     {
         $relativeCN         = str_replace(__NAMESPACE__.'\\', '', get_called_class());
         self::$caseFileName = __DIR__.DIRECTORY_SEPARATOR.$relativeCN.'.inc';
@@ -51,21 +49,19 @@ public static function copyCaseFile()
             throw new Exception(sprintf('Failed to copy test case file "ReplaceTabsInTokenTest.inc" to %s', self::$caseFileName));
         }
 
-    }//end copyCaseFile()
+    }//end setUpBeforeClass()
 
 
     /**
      * Delete the copied test case file after use.
      *
-     * @afterClass
-     *
      * @return void
      */
-    public static function deleteCaseFile()
+    public static function tearDownAfterClass(): void
     {
         @unlink(self::$caseFileName);
 
-    }//end deleteCaseFile()
+    }//end tearDownAfterClass()
 
 
     /**
diff --git a/tests/Core/Util/Common/GetSniffCodeTest.php b/tests/Core/Util/Common/GetSniffCodeTest.php
index 4b4083dedf..a2e92a923f 100644
--- a/tests/Core/Util/Common/GetSniffCodeTest.php
+++ b/tests/Core/Util/Common/GetSniffCodeTest.php
@@ -35,14 +35,8 @@ public function testGetSniffCodeThrowsExceptionOnInvalidInput($input)
         $exception = 'InvalidArgumentException';
         $message   = 'The $sniffClass parameter must be a non-empty string';
 
-        if (method_exists($this, 'expectException') === true) {
-            // PHPUnit 5+.
-            $this->expectException($exception);
-            $this->expectExceptionMessage($message);
-        } else {
-            // PHPUnit 4.
-            $this->setExpectedException($exception, $message);
-        }
+        $this->expectException($exception);
+        $this->expectExceptionMessage($message);
 
         Common::getSniffCode($input);
 
@@ -81,14 +75,8 @@ public function testGetSniffCodeThrowsExceptionOnInputWhichIsNotASniffTestClass(
         $exception = 'InvalidArgumentException';
         $message   = 'The $sniffClass parameter was not passed a fully qualified sniff(test) class name. Received:';
 
-        if (method_exists($this, 'expectException') === true) {
-            // PHPUnit 5+.
-            $this->expectException($exception);
-            $this->expectExceptionMessage($message);
-        } else {
-            // PHPUnit 4.
-            $this->setExpectedException($exception, $message);
-        }
+        $this->expectException($exception);
+        $this->expectExceptionMessage($message);
 
         Common::getSniffCode($input);
 
diff --git a/tests/Core/Util/Common/PrepareForOutputTest.php b/tests/Core/Util/Common/PrepareForOutputTest.php
index 8eb2fc22f9..3f4d595a4b 100644
--- a/tests/Core/Util/Common/PrepareForOutputTest.php
+++ b/tests/Core/Util/Common/PrepareForOutputTest.php
@@ -49,7 +49,7 @@ public function testPrepareForOutput($content, $exclude, $expected, $expectedWin
      * @param string   $expected    Expected function output (unused in this test).
      * @param string   $expectedWin Expected function output on Windows.
      *
-     * @requires     OS ^WIN.*.
+     * @requires     OSFAMILY Windows
      * @dataProvider dataPrepareForOutput
      *
      * @return void
diff --git a/tests/Core/Util/Help/HelpTest.php b/tests/Core/Util/Help/HelpTest.php
index b3d51a5c78..8249b3d2a9 100644
--- a/tests/Core/Util/Help/HelpTest.php
+++ b/tests/Core/Util/Help/HelpTest.php
@@ -150,14 +150,8 @@ public function testConstructorInvalidArgumentException()
         $exception = 'InvalidArgumentException';
         $message   = 'The $shortOptions parameter must be a string';
 
-        if (method_exists($this, 'expectException') === true) {
-            // PHPUnit 5+.
-            $this->expectException($exception);
-            $this->expectExceptionMessage($message);
-        } else {
-            // PHPUnit 4.
-            $this->setExpectedException($exception, $message);
-        }
+        $this->expectException($exception);
+        $this->expectExceptionMessage($message);
 
         new Help(new ConfigDouble(), [], []);
 
diff --git a/tests/Core/Util/MessageCollector/MessageCollectorTest.php b/tests/Core/Util/MessageCollector/MessageCollectorTest.php
index faa98ca415..0f69967784 100644
--- a/tests/Core/Util/MessageCollector/MessageCollectorTest.php
+++ b/tests/Core/Util/MessageCollector/MessageCollectorTest.php
@@ -33,14 +33,9 @@ public function testAddingNonStringMessageResultsInException($message)
     {
         $exception    = 'InvalidArgumentException';
         $exceptionMsg = 'The $message should be of type string. Received: ';
-        if (method_exists($this, 'expectException') === true) {
-            // PHPUnit 5+.
-            $this->expectException($exception);
-            $this->expectExceptionMessage($exceptionMsg);
-        } else {
-            // PHPUnit 4.
-            $this->setExpectedException($exception, $exceptionMsg);
-        }
+
+        $this->expectException($exception);
+        $this->expectExceptionMessage($exceptionMsg);
 
         $msgCollector = new MessageCollector();
         $msgCollector->add($message);
@@ -80,14 +75,9 @@ public function testAddingMessageWithUnsupportedMessageTypeResultsInException($t
     {
         $exception    = 'InvalidArgumentException';
         $exceptionMsg = 'The message $type should be one of the predefined MessageCollector constants. Received: ';
-        if (method_exists($this, 'expectException') === true) {
-            // PHPUnit 5+.
-            $this->expectException($exception);
-            $this->expectExceptionMessage($exceptionMsg);
-        } else {
-            // PHPUnit 4.
-            $this->setExpectedException($exception, $exceptionMsg);
-        }
+
+        $this->expectException($exception);
+        $this->expectExceptionMessage($exceptionMsg);
 
         $msgCollector = new MessageCollector();
         $msgCollector->add('Message', $type);
@@ -309,14 +299,9 @@ public static function dataDisplayingNonBlockingMessages()
     public function testDisplayingBlockingErrors($messages, $expected)
     {
         $exception = 'PHP_CodeSniffer\Exceptions\RuntimeException';
-        if (method_exists($this, 'expectException') === true) {
-            // PHPUnit 5+.
-            $this->expectException($exception);
-            $this->expectExceptionMessage($expected);
-        } else {
-            // PHPUnit 4.
-            $this->setExpectedException($exception, $expected);
-        }
+
+        $this->expectException($exception);
+        $this->expectExceptionMessage($expected);
 
         $msgCollector = new MessageCollector();
         $this->createErrorCache($msgCollector, $messages);
diff --git a/tests/Core/Util/Timing/TimingTest.php b/tests/Core/Util/Timing/TimingTest.php
index f5ef115643..a8cf2d04e4 100644
--- a/tests/Core/Util/Timing/TimingTest.php
+++ b/tests/Core/Util/Timing/TimingTest.php
@@ -51,7 +51,7 @@ public function testGetDurationWithStartReturnsMilliseconds()
         usleep(1500);
         $duration = Timing::getDuration();
 
-        $this->assertTrue(is_float($duration));
+        $this->assertIsFloat($duration);
         $this->assertGreaterThan(1, $duration);
         $this->assertLessThan(15, $duration);
 
diff --git a/tests/Standards/AbstractSniffUnitTest.php b/tests/Standards/AbstractSniffUnitTest.php
index ccd90c513c..a62374cf55 100644
--- a/tests/Standards/AbstractSniffUnitTest.php
+++ b/tests/Standards/AbstractSniffUnitTest.php
@@ -51,17 +51,15 @@ abstract class AbstractSniffUnitTest extends TestCase
     /**
      * Sets up this unit test.
      *
-     * @before
-     *
      * @return void
      */
-    protected function setUpPrerequisites()
+    protected function setUp(): void
     {
         $class = get_class($this);
         $this->standardsDir = $GLOBALS['PHP_CODESNIFFER_STANDARD_DIRS'][$class];
         $this->testsDir     = $GLOBALS['PHP_CODESNIFFER_TEST_DIRS'][$class];
 
-    }//end setUpPrerequisites()
+    }//end setUp()
 
 
     /**
diff --git a/tests/TestSuite.php b/tests/TestSuite.php
index 4598a85623..ad0947c58f 100644
--- a/tests/TestSuite.php
+++ b/tests/TestSuite.php
@@ -19,11 +19,11 @@ class TestSuite extends PHPUnit_TestSuite
     /**
      * Runs the tests and collects their result in a TestResult.
      *
-     * @param \PHPUnit\Framework\TestResult $result A test result.
+     * @param \PHPUnit\Framework\TestResult|null $result A test result.
      *
      * @return \PHPUnit\Framework\TestResult
      */
-    public function run(TestResult $result=null)
+    public function run(?TestResult $result=null): TestResult
     {
         $result = parent::run($result);
         printPHPCodeSnifferTestOutput();
diff --git a/tests/TestSuite7.php b/tests/TestSuite7.php
deleted file mode 100644
index ad0947c58f..0000000000
--- a/tests/TestSuite7.php
+++ /dev/null
@@ -1,35 +0,0 @@
-<?php
-/**
- * A PHP_CodeSniffer specific test suite for PHPUnit.
- *
- * @author    Greg Sherwood <gsherwood@squiz.net>
- * @copyright 2006-2015 Squiz Pty Ltd (ABN 77 084 670 600)
- * @license   https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/master/licence.txt BSD Licence
- */
-
-namespace PHP_CodeSniffer\Tests;
-
-use PHPUnit\Framework\TestResult;
-use PHPUnit\Framework\TestSuite as PHPUnit_TestSuite;
-
-class TestSuite extends PHPUnit_TestSuite
-{
-
-
-    /**
-     * Runs the tests and collects their result in a TestResult.
-     *
-     * @param \PHPUnit\Framework\TestResult|null $result A test result.
-     *
-     * @return \PHPUnit\Framework\TestResult
-     */
-    public function run(?TestResult $result=null): TestResult
-    {
-        $result = parent::run($result);
-        printPHPCodeSnifferTestOutput();
-        return $result;
-
-    }//end run()
-
-
-}//end class
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index e8ebdbbdd0..f90d98c49f 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -42,23 +42,6 @@
 
 $tokens = new \PHP_CodeSniffer\Util\Tokens();
 
-// Compatibility for PHPUnit < 6 and PHPUnit 6+.
-if (class_exists('PHPUnit_Framework_TestSuite') === true && class_exists('PHPUnit\Framework\TestSuite') === false) {
-    class_alias('PHPUnit_Framework_TestSuite', 'PHPUnit'.'\Framework\TestSuite');
-}
-
-if (class_exists('PHPUnit_Framework_TestCase') === true && class_exists('PHPUnit\Framework\TestCase') === false) {
-    class_alias('PHPUnit_Framework_TestCase', 'PHPUnit'.'\Framework\TestCase');
-}
-
-if (class_exists('PHPUnit_TextUI_TestRunner') === true && class_exists('PHPUnit\TextUI\TestRunner') === false) {
-    class_alias('PHPUnit_TextUI_TestRunner', 'PHPUnit'.'\TextUI\TestRunner');
-}
-
-if (class_exists('PHPUnit_Framework_TestResult') === true && class_exists('PHPUnit\Framework\TestResult') === false) {
-    class_alias('PHPUnit_Framework_TestResult', 'PHPUnit'.'\Framework\TestResult');
-}
-
 
 /**
  * A global util function to help print unit test fixing data.