diff --git a/dev/tests/api-functional/framework/Magento/TestFramework/Authentication/Rest/CurlClient.php b/dev/tests/api-functional/framework/Magento/TestFramework/Authentication/Rest/CurlClient.php
index 1c1d1bb7cea5a..43491f0949d31 100644
--- a/dev/tests/api-functional/framework/Magento/TestFramework/Authentication/Rest/CurlClient.php
+++ b/dev/tests/api-functional/framework/Magento/TestFramework/Authentication/Rest/CurlClient.php
@@ -13,7 +13,7 @@
 class CurlClient extends \OAuth\Common\Http\Client\CurlClient
 {
     /**
-     * {@inheritdoc}
+     * @inheritdoc
      */
     public function retrieveResponse(
         UriInterface $endpoint,
diff --git a/dev/tests/static/framework/Magento/TestFramework/Integrity/Library/PhpParser/StaticCalls.php b/dev/tests/static/framework/Magento/TestFramework/Integrity/Library/PhpParser/StaticCalls.php
index e70c7c3b5c1c6..f1f9d68491f33 100644
--- a/dev/tests/static/framework/Magento/TestFramework/Integrity/Library/PhpParser/StaticCalls.php
+++ b/dev/tests/static/framework/Magento/TestFramework/Integrity/Library/PhpParser/StaticCalls.php
@@ -82,6 +82,13 @@ protected function getClassByStaticCall($staticCall)
     {
         $step = 1;
         $staticClassParts = [];
+
+        $token = $this->tokens->getTokenCodeByKey($staticCall - $step);
+        if ($token === T_NAME_FULLY_QUALIFIED || $token === T_NAME_QUALIFIED) {
+            return $this->tokens->getTokenValueByKey($staticCall - $step);
+        }
+
+        // PHP 7 compatibility
         while ($this->tokens->getTokenCodeByKey(
             $staticCall - $step
         ) == T_STRING || $this->tokens->getTokenCodeByKey(
@@ -90,6 +97,7 @@ protected function getClassByStaticCall($staticCall)
             $staticClassParts[] = $this->tokens->getTokenValueByKey($staticCall - $step);
             $step++;
         }
+
         return implode(array_reverse($staticClassParts));
     }
 
diff --git a/dev/tests/static/framework/Magento/TestFramework/Integrity/Library/PhpParser/Throws.php b/dev/tests/static/framework/Magento/TestFramework/Integrity/Library/PhpParser/Throws.php
index 5e60333b24492..e14b3f21ab95c 100644
--- a/dev/tests/static/framework/Magento/TestFramework/Integrity/Library/PhpParser/Throws.php
+++ b/dev/tests/static/framework/Magento/TestFramework/Integrity/Library/PhpParser/Throws.php
@@ -57,14 +57,19 @@ public function getDependencies(Uses $uses)
             $class = '';
             if ($this->tokens->getTokenCodeByKey($throw + 2) == T_NEW) {
                 $step = 4;
-                while ($this->tokens->getTokenCodeByKey(
-                    $throw + $step
-                ) == T_STRING || $this->tokens->getTokenCodeByKey(
-                    $throw + $step
-                ) == T_NS_SEPARATOR) {
-                    $class .= trim($this->tokens->getTokenValueByKey($throw + $step));
-                    $step++;
+
+                $token = $this->tokens->getTokenCodeByKey($throw + $step);
+                if ($token === T_NAME_FULLY_QUALIFIED || $token === T_NAME_QUALIFIED) {
+                    $class = $this->tokens->getTokenValueByKey($throw + $step);
+                } else {
+                    // PHP 7 compatibility
+                    while ($this->tokens->getTokenCodeByKey($throw + $step) === T_STRING
+                        || $this->tokens->getTokenCodeByKey($throw + $step) === T_NS_SEPARATOR) {
+                        $class .= trim($this->tokens->getTokenValueByKey($throw + $step));
+                        $step++;
+                    }
                 }
+
                 if ($uses->hasUses()) {
                     $class = $uses->getClassNameWithNamespace($class);
                 }
diff --git a/dev/tests/static/testsuite/Magento/Test/Integrity/Di/CompilerTest.php b/dev/tests/static/testsuite/Magento/Test/Integrity/Di/CompilerTest.php
index 622dfb329acac..0a917a8a3f20d 100644
--- a/dev/tests/static/testsuite/Magento/Test/Integrity/Di/CompilerTest.php
+++ b/dev/tests/static/testsuite/Magento/Test/Integrity/Di/CompilerTest.php
@@ -127,11 +127,9 @@ private function getPluginBlacklist(): array
             );
             $blacklistItems = [];
             foreach (glob($blacklistFiles) as $fileName) {
-                $blacklistItems = array_merge(
-                    $blacklistItems,
-                    file($fileName, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES)
-                );
+                $blacklistItems[] = file($fileName, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
             }
+            $blacklistItems = array_merge([], ...$blacklistItems);
             $this->pluginBlacklist = $blacklistItems;
         }
         return $this->pluginBlacklist;
@@ -243,10 +241,10 @@ protected function _phpClassesDataProvider()
         $allowedFiles = array_keys($classes);
         foreach ($classes as $class) {
             if (!in_array($class, $output)) {
-                $output = array_merge($output, $this->_buildInheritanceHierarchyTree($class, $allowedFiles));
-                $output = array_unique($output);
+                $output[] = $this->_buildInheritanceHierarchyTree($class, $allowedFiles);
             }
         }
+        $output = array_unique(array_merge([], ...$output));
 
         /** Convert data into data provider format */
         $outputClasses = [];
@@ -409,7 +407,7 @@ protected function pluginDataProvider()
                     $plugin = $node->attributes->getNamedItem('type')->nodeValue;
                     if (!in_array($plugin, $this->getPluginBlacklist())) {
                         $plugin = \Magento\Framework\App\Utility\Classes::resolveVirtualType($plugin);
-                        $plugins[] = ['plugin' => $plugin, 'intercepted type' => $type];
+                        $plugins[] = [$plugin, $type];
                     }
                 }
             }
diff --git a/dev/tests/static/testsuite/Magento/Test/Integrity/Magento/Framework/Api/ExtensibleInterfacesTest.php b/dev/tests/static/testsuite/Magento/Test/Integrity/Magento/Framework/Api/ExtensibleInterfacesTest.php
index d7ed6e2127f44..323f379fdffa9 100644
--- a/dev/tests/static/testsuite/Magento/Test/Integrity/Magento/Framework/Api/ExtensibleInterfacesTest.php
+++ b/dev/tests/static/testsuite/Magento/Test/Integrity/Magento/Framework/Api/ExtensibleInterfacesTest.php
@@ -135,9 +135,10 @@ private function checkSetExtensionAttributes(
             } else {
                 // Get the parameter name via a regular expression capture because the class may
                 // not exist which causes a fatal error
-                preg_match('/\[\s\<\w+?>\s([\w]+)/s', $methodParameters[0]->__toString(), $matches);
+                preg_match('/\[\s\<\w+?>\s([?]?[\w\\\]+)/s', $methodParameters[0]->__toString(), $matches);
                 $isCorrectParameter = false;
-                if (isset($matches[1]) && '\\' . $matches[1] != $extensionInterfaceName) {
+                if (isset($matches[1])
+                    && ('\\' . ltrim($matches[1], '?')) === $extensionInterfaceName) {
                     $isCorrectParameter = true;
                 }
 
diff --git a/dev/tests/static/testsuite/Magento/Test/Integrity/PublicCodeTest.php b/dev/tests/static/testsuite/Magento/Test/Integrity/PublicCodeTest.php
index 59183dc174682..2c94ab8ead5fc 100644
--- a/dev/tests/static/testsuite/Magento/Test/Integrity/PublicCodeTest.php
+++ b/dev/tests/static/testsuite/Magento/Test/Integrity/PublicCodeTest.php
@@ -11,6 +11,7 @@
 use PHPUnit\Framework\TestCase;
 use ReflectionClass;
 use ReflectionException;
+use ReflectionMethod;
 use ReflectionParameter;
 
 /**
@@ -111,9 +112,9 @@ public function testAllPHPClassesReferencedFromPublicClassesArePublic($class)
     {
         $nonPublishedClasses = [];
         $reflection = new \ReflectionClass($class);
-        $filter = \ReflectionMethod::IS_PUBLIC;
+        $filter = ReflectionMethod::IS_PUBLIC;
         if ($reflection->isAbstract()) {
-            $filter = $filter | \ReflectionMethod::IS_PROTECTED;
+            $filter = $filter | ReflectionMethod::IS_PROTECTED;
         }
         $methods = $reflection->getMethods($filter);
         foreach ($methods as $method) {
@@ -125,8 +126,11 @@ public function testAllPHPClassesReferencedFromPublicClassesArePublic($class)
              is written on early php 7 when return types are not actively used */
             $returnTypes = [];
             if ($method->hasReturnType()) {
-                if (!$method->getReturnType()->isBuiltin()) {
-                    $returnTypes = [trim($method->getReturnType()->getName(), '?[]')];
+                $methodReturnType = $method->getReturnType();
+                // For PHP 8.0 - ReflectionUnionType doesn't have isBuiltin method.
+                if (method_exists($methodReturnType, 'isBuiltin')
+                    && !$methodReturnType->isBuiltin()) {
+                    $returnTypes = [trim($methodReturnType->getName(), '?[]')];
                 }
             } else {
                 $returnTypes = $this->getReturnTypesFromDocComment($method->getDocComment());
@@ -260,16 +264,20 @@ private function checkReturnValues($class, array $returnTypes, array $nonPublish
 
     /**
      * Check if all method parameters are public
+     *
      * @param string $class
-     * @param \ReflectionMethod $method
+     * @param ReflectionMethod $method
      * @param array $nonPublishedClasses
+     *
      * @return array
+     * @SuppressWarnings(PHPMD.CyclomaticComplexity)
      */
-    private function checkParameters($class, \ReflectionMethod $method, array $nonPublishedClasses)
+    private function checkParameters($class, ReflectionMethod $method, array $nonPublishedClasses)
     {
         /* Ignoring docblocks for argument types */
         foreach ($method->getParameters() as $parameter) {
             if ($parameter->hasType()
+                && method_exists($parameter->getType(), 'isBuiltin')
                 && !$parameter->getType()->isBuiltin()
                 && !$this->isGenerated($parameter->getType()->getName())
             ) {
diff --git a/dev/tests/static/testsuite/Magento/Test/Integrity/Readme/ReadmeTest.php b/dev/tests/static/testsuite/Magento/Test/Integrity/Readme/ReadmeTest.php
index 050c9ca05a5ef..053da8c41d55a 100644
--- a/dev/tests/static/testsuite/Magento/Test/Integrity/Readme/ReadmeTest.php
+++ b/dev/tests/static/testsuite/Magento/Test/Integrity/Readme/ReadmeTest.php
@@ -57,7 +57,7 @@ private function getDirectories()
         $directories = [];
         foreach ($this->scanList as $dir) {
             if (!$this->isInBlacklist($dir)) {
-                $directories[][$dir] = $dir;
+                $directories[][] = $dir;
             }
         }