update phpunit

Author: marc-mabe

.gitattributes

@@ -6,4 +6,5 @@
 .travis.yml export-ignore
 phpbench.json export-ignore
 phpunit.xml.dist export-ignore
+phpstan.neon.dist export-ignore
 psalm.xml export-ignore

.gitignore

@@ -11,3 +11,6 @@ vendor
 
 #phpbench
 _storage
+
+#phpunit
+.phpunit.result.cache

composer.json

@@ -23,7 +23,7 @@
     "require-dev": {
         "phpbench/phpbench": "^0.16.10",
         "phpstan/phpstan": "^0.12.42",
-        "phpunit/phpunit": "^7.5.20",
+        "phpunit/phpunit": "^7.5.20 | ^8.5.8 | ^9.3.8",
         "vimeo/psalm": "^3.15.0"
     },
     "autoload": {

tests/MabeEnumTest/EnumSerializableTraitTest.php

@@ -23,7 +23,7 @@ class EnumSerializableTraitTest extends TestCase
     public function testSerializeSerializableEnum(): void
     {
         $serialized = serialize(SerializableEnum::get(SerializableEnum::NIL));
-        $this->assertInternalType('string', $serialized);
+        $this->assertIsString($serialized);
 
         $unserialized = unserialize($serialized);
         $this->assertInstanceOf(SerializableEnum::class, $unserialized);
@@ -32,7 +32,7 @@ public function testSerializeSerializableEnum(): void
     public function testUnserializeFirstWillHoldTheSameInstance(): void
     {
         $serialized = serialize(SerializableEnum::get(SerializableEnum::STR));
-        $this->assertInternalType('string', $serialized);
+        $this->assertIsString($serialized);
 
         // clear all instantiated instances so we can virtual test unserializing first
         $this->clearEnumeration(SerializableEnum::class);
@@ -74,7 +74,7 @@ public function testInheritence(): void
         $enum = ExtendedSerializableEnum::EXTENDED();
 
         $serialized = serialize($enum);
-        $this->assertInternalType('string', $serialized);
+        $this->assertIsString($serialized);
 
         $unserialized = unserialize($serialized);
         $this->assertInstanceOf(ExtendedSerializableEnum::class, $unserialized);