diff --git a/phpunit.xml b/phpunit.xml
index 07b339d..52f96fc 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -2,7 +2,8 @@
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/11.0/phpunit.xsd" colors="true" bootstrap="vendor/autoload.php" cacheDirectory=".phpunit.cache">
   <testsuites>
     <testsuite name="CallbackValidator Test Suite">
-      <directory>./tests</directory>
+      <directory>./tests/Base</directory>
+      <directory phpVersion="8.2.0" phpVersionOperator=">=">./tests/Php82</directory>
     </testsuite>
   </testsuites>
   <source>
diff --git a/tests/CallbackTypeTest.php b/tests/Base/CallbackTypeTest.php
similarity index 86%
rename from tests/CallbackTypeTest.php
rename to tests/Base/CallbackTypeTest.php
index 5b325b1..b5c7f06 100644
--- a/tests/CallbackTypeTest.php
+++ b/tests/Base/CallbackTypeTest.php
@@ -1,10 +1,10 @@
 <?php
 
-namespace DaveRandom\CallbackValidator\Test;
+namespace DaveRandom\CallbackValidator\Test\Base;
 
 use DaveRandom\CallbackValidator\CallbackType;
-use DaveRandom\CallbackValidator\Test\Fixtures\Interface1;
-use DaveRandom\CallbackValidator\Test\Fixtures\Interface2;
+use DaveRandom\CallbackValidator\Test\Base\Fixtures\Interface1;
+use DaveRandom\CallbackValidator\Test\Base\Fixtures\Interface2;
 use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\TestCase;
 
@@ -26,10 +26,6 @@ public static function returnCovarianceProvider() : \Generator{
 		yield [function() : Interface1{}, function() : Interface1&Interface2{}, true, "covariant intersection type"];
 		yield [function() : Interface1&Interface2{}, function() : Interface1{}, false, "given type not covariant with required intersection"];
 
-		//DNF types - PHP 8.2+ only
-		yield [function() : (Interface1&Interface2)|string{}, function() : Interface1{}, false, "given type not covariant with any part of required union"];
-		yield [function() : (Interface1&Interface2)|string{}, function() : Interface1&Interface2{}, true, "given type covariant with at least 1 part of required union"];
-
 		yield [function() : mixed{}, function() : int{}, true, "int is covariant with mixed"];
 		yield [function() : mixed{}, function() : int|string{}, true, "int|string is covariant with mixed"];
 		yield [function() : mixed{}, function() : Interface1&Interface2{}, true, "intersection is covariant with mixed"];
@@ -55,9 +51,6 @@ public static function paramContravarianceProvider() : \Generator{
 		yield [function(Interface1&Interface2 $a) : void{}, function(Interface1&Interface2 $a) : void{}, true, "same type"];
 		yield [function(Interface1 $a) : void{}, function(Interface1&Interface2 $a) : void{}, false, "intersection given is not contravariant with required"];
 
-		yield [function((Interface1&Interface2)|string $a) : void{}, function(Interface1&Interface2 $a) : void{}, false, "given type must accept string"];
-		yield [function(Interface1&Interface2 $a) : void{}, function((Interface1&Interface2)|string $a) : void{}, true, "given type accepts string, which is not required by the signature"];
-
 		yield [function(int $a) : void{}, function(float $a) : void{}, true, "float is contravariant with int"];
 
 		yield [function(int $a = 0) : void{}, function(int $a) : void{}, false, "required parameter cannot satisfy optional"];
@@ -77,7 +70,6 @@ public static function paramContravarianceProvider() : \Generator{
 		yield [function(int $a) : void{}, function(mixed $a) : void{}, true, "mixed is contravariant with int"];
 		yield [function(int|string $a) : void{}, function(mixed $a) : void{}, true, "mixed is contravariant with int|string"];
 		yield [function(Interface1&Interface2 $a) : void{}, function(mixed $a) : void{}, true, "mixed is contravariant with intersection"];
-		yield [function((Interface1&Interface2)|string $a) : void{}, function(mixed $a) : void{}, true, "mixed is contravariant with DNF type"];
 
 		yield [function(mixed $a) : void{}, function($a) : void{}, true, "unspecified parameter type is equivalent to mixed"];
 
diff --git a/tests/Fixtures/ClassImplementingInvoke.php b/tests/Base/Fixtures/ClassImplementingInvoke.php
similarity index 63%
rename from tests/Fixtures/ClassImplementingInvoke.php
rename to tests/Base/Fixtures/ClassImplementingInvoke.php
index 21978e7..5f2a69a 100644
--- a/tests/Fixtures/ClassImplementingInvoke.php
+++ b/tests/Base/Fixtures/ClassImplementingInvoke.php
@@ -1,6 +1,6 @@
 <?php declare(strict_types = 1);
 
-namespace DaveRandom\CallbackValidator\Test\Fixtures;
+namespace DaveRandom\CallbackValidator\Test\Base\Fixtures;
 
 class ClassImplementingInvoke
 {
diff --git a/tests/Fixtures/ClassImplementingIteratorAggregate.php b/tests/Base/Fixtures/ClassImplementingIteratorAggregate.php
similarity index 66%
rename from tests/Fixtures/ClassImplementingIteratorAggregate.php
rename to tests/Base/Fixtures/ClassImplementingIteratorAggregate.php
index 7d6f753..430432f 100644
--- a/tests/Fixtures/ClassImplementingIteratorAggregate.php
+++ b/tests/Base/Fixtures/ClassImplementingIteratorAggregate.php
@@ -1,5 +1,5 @@
 <?php declare(strict_types = 1);
 
-namespace DaveRandom\CallbackValidator\Test\Fixtures;
+namespace DaveRandom\CallbackValidator\Test\Base\Fixtures;
 
 abstract class ClassImplementingIteratorAggregate implements \IteratorAggregate {}
diff --git a/tests/Fixtures/ClassImplementingNothing.php b/tests/Base/Fixtures/ClassImplementingNothing.php
similarity index 53%
rename from tests/Fixtures/ClassImplementingNothing.php
rename to tests/Base/Fixtures/ClassImplementingNothing.php
index 39e5e66..cfee266 100644
--- a/tests/Fixtures/ClassImplementingNothing.php
+++ b/tests/Base/Fixtures/ClassImplementingNothing.php
@@ -1,5 +1,5 @@
 <?php declare(strict_types = 1);
 
-namespace DaveRandom\CallbackValidator\Test\Fixtures;
+namespace DaveRandom\CallbackValidator\Test\Base\Fixtures;
 
 class ClassImplementingNothing {}
diff --git a/tests/Fixtures/ClassImplementingToString.php b/tests/Base/Fixtures/ClassImplementingToString.php
similarity index 66%
rename from tests/Fixtures/ClassImplementingToString.php
rename to tests/Base/Fixtures/ClassImplementingToString.php
index 248ea55..70c3acc 100644
--- a/tests/Fixtures/ClassImplementingToString.php
+++ b/tests/Base/Fixtures/ClassImplementingToString.php
@@ -1,6 +1,6 @@
 <?php declare(strict_types = 1);
 
-namespace DaveRandom\CallbackValidator\Test\Fixtures;
+namespace DaveRandom\CallbackValidator\Test\Base\Fixtures;
 
 class ClassImplementingToString
 {
diff --git a/tests/Base/Fixtures/Interface1.php b/tests/Base/Fixtures/Interface1.php
new file mode 100644
index 0000000..0a4938c
--- /dev/null
+++ b/tests/Base/Fixtures/Interface1.php
@@ -0,0 +1,7 @@
+<?php
+
+namespace DaveRandom\CallbackValidator\Test\Base\Fixtures;
+
+interface Interface1{
+
+}
diff --git a/tests/Base/Fixtures/Interface2.php b/tests/Base/Fixtures/Interface2.php
new file mode 100644
index 0000000..980b742
--- /dev/null
+++ b/tests/Base/Fixtures/Interface2.php
@@ -0,0 +1,7 @@
+<?php
+
+namespace DaveRandom\CallbackValidator\Test\Base\Fixtures;
+
+interface Interface2{
+
+}
diff --git a/tests/Fixtures/Interface1.php b/tests/Fixtures/Interface1.php
deleted file mode 100644
index 70b8d4a..0000000
--- a/tests/Fixtures/Interface1.php
+++ /dev/null
@@ -1,7 +0,0 @@
-<?php
-
-namespace DaveRandom\CallbackValidator\Test\Fixtures;
-
-interface Interface1{
-
-}
diff --git a/tests/Fixtures/Interface2.php b/tests/Fixtures/Interface2.php
deleted file mode 100644
index 1faa433..0000000
--- a/tests/Fixtures/Interface2.php
+++ /dev/null
@@ -1,7 +0,0 @@
-<?php
-
-namespace DaveRandom\CallbackValidator\Test\Fixtures;
-
-interface Interface2{
-
-}
diff --git a/tests/Php82/CallbackTypeTest.php b/tests/Php82/CallbackTypeTest.php
new file mode 100644
index 0000000..9ebc355
--- /dev/null
+++ b/tests/Php82/CallbackTypeTest.php
@@ -0,0 +1,36 @@
+<?php
+
+namespace DaveRandom\CallbackValidator\Test\Php82;
+
+use DaveRandom\CallbackValidator\CallbackType;
+use DaveRandom\CallbackValidator\Test\Base\Fixtures\Interface1;
+use DaveRandom\CallbackValidator\Test\Base\Fixtures\Interface2;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\TestCase;
+
+class CallbackTypeTest extends TestCase{
+
+	public static function returnCovarianceProvider() : \Generator{
+		//DNF types - PHP 8.2+ only
+		yield [function() : (Interface1&Interface2)|string{}, function() : Interface1{}, false, "given type not covariant with any part of required union"];
+		yield [function() : (Interface1&Interface2)|string{}, function() : Interface1&Interface2{}, true, "given type covariant with at least 1 part of required union"];
+	}
+
+	public static function paramContravarianceProvider() : \Generator{
+		//DNF types - PHP 8.2+ only
+		yield [function((Interface1&Interface2)|string $a) : void{}, function(Interface1&Interface2 $a) : void{}, false, "given type must accept string"];
+		yield [function(Interface1&Interface2 $a) : void{}, function((Interface1&Interface2)|string $a) : void{}, true, "given type accepts string, which is not required by the signature"];
+
+		yield [function((Interface1&Interface2)|string $a) : void{}, function(mixed $a) : void{}, true, "mixed is contravariant with DNF type"];
+	}
+
+	#[DataProvider('returnCovarianceProvider')]
+	#[DataProvider('paramContravarianceProvider')]
+	public function testCompatibility(\Closure $required, \Closure $given, bool $matches, string $reason) : void{
+		$required = CallbackType::createFromCallable($required);
+
+		$serializedRequire = (string) $required;
+		$serializedGiven = (string) CallbackType::createFromCallable($given);
+		self::assertSame($required->isSatisfiedBy($given), $matches, $reason . " ($serializedRequire, $serializedGiven)");
+	}
+}