diff --git a/.github/workflows/php.yml b/.github/workflows/php.yml
index 9c67e3a..3ad0492 100644
--- a/.github/workflows/php.yml
+++ b/.github/workflows/php.yml
@@ -78,7 +78,7 @@ jobs:
         run: composer install --no-progress --prefer-dist --optimize-autoloader
 
       - name: Check code for hard dependencies missing in composer.json
-        run: composer-require-checker check composer.json
+        run: composer-require-checker check --config-file=tools/composer-require-checker.json composer.json
 
       - name: Check code for unused dependencies in composer.json
         run: composer-unused
diff --git a/composer.json b/composer.json
index 172013d..57cbd22 100644
--- a/composer.json
+++ b/composer.json
@@ -37,7 +37,7 @@
         "simplesamlphp/assert": "^1.1"
     },
     "require-dev": {
-        "simplesamlphp/simplesamlphp-test-framework": "^1.5"
+        "simplesamlphp/simplesamlphp-test-framework": "^1.6"
     },
     "support": {
         "issues": "https://github.com/simplesamlphp/xml-common/issues",
diff --git a/src/TestUtils/SchemaValidationTestTrait.php b/src/TestUtils/SchemaValidationTestTrait.php
index c9ebf8d..bf5048e 100644
--- a/src/TestUtils/SchemaValidationTestTrait.php
+++ b/src/TestUtils/SchemaValidationTestTrait.php
@@ -7,6 +7,7 @@
 use DOMDocument;
 use Exception;
 use LibXMLError; // Officially spelled with a lower-case `l`, but that breaks composer-require-checker
+use PHPUnit\Framework\Attributes\Depends;
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\XML\Exception\SchemaViolationException;
 use XMLReader;
@@ -37,9 +38,8 @@ trait SchemaValidationTestTrait
 
     /**
      * Test schema validation.
-     *
-     * @depends testSerialization
      */
+    #[Depends('testSerialization')]
     public function testSchemaValidation(): void
     {
         if (!class_exists(self::$testedClass)) {
diff --git a/src/TestUtils/SerializableElementTestTrait.php b/src/TestUtils/SerializableElementTestTrait.php
index 27736a1..ede744e 100644
--- a/src/TestUtils/SerializableElementTestTrait.php
+++ b/src/TestUtils/SerializableElementTestTrait.php
@@ -5,6 +5,7 @@
 namespace SimpleSAML\XML\TestUtils;
 
 use DOMDocument;
+use PHPUnit\Framework\Attributes\Depends;
 
 use function class_exists;
 
@@ -56,10 +57,9 @@ public function testUnmarshalling(): void
 
     /**
      * Test serialization / unserialization.
-     *
-     * @depends testMarshalling
-     * @depends testUnmarshalling
      */
+    #[Depends('testMarshalling')]
+    #[Depends('testUnmarshalling')]
     public function testSerialization(): void
     {
         if (!class_exists(self::$testedClass)) {
diff --git a/tests/Utils/RandomTest.php b/tests/Utils/RandomTest.php
index 507c6c4..1e671ed 100644
--- a/tests/Utils/RandomTest.php
+++ b/tests/Utils/RandomTest.php
@@ -4,6 +4,7 @@
 
 namespace SimpleSAML\Test\XML\Utils;
 
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\XML\Utils\Random;
 
@@ -11,9 +12,8 @@
 
 /**
  * Tests for SimpleSAML\XML\Utils\Random.
- *
- * @covers \SimpleSAML\XML\Utils\Random
  */
+#[CoversClass(Random::class)]
 class RandomTest extends TestCase
 {
     /**
diff --git a/tests/XML/AbstractElementTest.php b/tests/XML/AbstractElementTest.php
index 8f91d9b..1f87099 100644
--- a/tests/XML/AbstractElementTest.php
+++ b/tests/XML/AbstractElementTest.php
@@ -4,8 +4,10 @@
 
 namespace SimpleSAML\Test\XML;
 
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\Test\XML\Element;
+use SimpleSAML\XML\AbstractElement;
 use SimpleSAML\XML\DOMDocumentFactory;
 use SimpleSAML\XML\Exception\MissingAttributeException;
 use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
@@ -16,11 +18,10 @@
 /**
  * Class \SimpleSAML\XML\AbstractElementTest
  *
- * @covers \SimpleSAML\XML\TestUtils\SerializableElementTestTrait
- * @covers \SimpleSAML\XML\AbstractElement
- *
  * @package simplesamlphp\xml-common
  */
+#[CoversClass(SerializableElementTestTrait::class)]
+#[CoversClass(AbstractElement::class)]
 final class AbstractElementTest extends TestCase
 {
     use SerializableElementTestTrait;
diff --git a/tests/XML/AttributeTest.php b/tests/XML/AttributeTest.php
index 549f137..84d9766 100644
--- a/tests/XML/AttributeTest.php
+++ b/tests/XML/AttributeTest.php
@@ -5,6 +5,7 @@
 namespace SimpleSAML\Test\XML;
 
 use DOMDocument;
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\XML\Attribute;
 use SimpleSAML\XML\DOMDocumentFactory;
@@ -13,11 +14,10 @@
 /**
  * Class \SimpleSAML\XML\AttributeTest
  *
- * @covers \SimpleSAML\XML\Attribute
- * @covers \SimpleSAML\XML\TestUtils\ArrayizableElementTestTrait
- *
  * @package simplesamlphp\xml-common
  */
+#[CoversClass(ArrayizableElementTestTrait::class)]
+#[CoversClass(Attribute::class)]
 final class AttributeTest extends TestCase
 {
     use ArrayizableElementTestTrait;
diff --git a/tests/XML/Base64ElementTraitTest.php b/tests/XML/Base64ElementTraitTest.php
index 8765f81..e817271 100644
--- a/tests/XML/Base64ElementTraitTest.php
+++ b/tests/XML/Base64ElementTraitTest.php
@@ -4,9 +4,14 @@
 
 namespace SimpleSAML\Test\XML;
 
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\Test\XML\XMLDumper;
+use SimpleSAML\XML\AbstractElement;
+use SimpleSAML\XML\Base64ElementTrait;
 use SimpleSAML\XML\DOMDocumentFactory;
+use SimpleSAML\XML\StringElementTrait;
 use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
 
 use function dirname;
@@ -15,13 +20,12 @@
 /**
  * Class \SimpleSAML\XML\Base64ElementTraitTest
  *
- * @covers \SimpleSAML\XML\TestUtils\SerializableElementTestTrait
- * @covers \SimpleSAML\XML\Base64ElementTrait
- * @covers \SimpleSAML\XML\StringElementTrait
- * @covers \SimpleSAML\XML\AbstractElement
- *
  * @package simplesamlphp\xml-common
  */
+#[CoversClass(SerializableElementTestTrait::class)]
+#[CoversClass(Base64ElementTrait::class)]
+#[CoversClass(StringElementTrait::class)]
+#[CoversClass(AbstractElement::class)]
 final class Base64ElementTraitTest extends TestCase
 {
     use SerializableElementTestTrait;
@@ -65,8 +69,8 @@ public function testUnmarshalling(): void
 
     /**
      * @param non-empty-string $xml
-     * @dataProvider provideBase64Cases
      */
+    #[DataProvider('provideBase64Cases')]
     public function testBase64Cases(string $xml): void
     {
         $xmlRepresentation = DOMDocumentFactory::fromString($xml);
diff --git a/tests/XML/BooleanElementTraitTest.php b/tests/XML/BooleanElementTraitTest.php
index 9565787..e31cc69 100644
--- a/tests/XML/BooleanElementTraitTest.php
+++ b/tests/XML/BooleanElementTraitTest.php
@@ -4,8 +4,11 @@
 
 namespace SimpleSAML\Test\XML;
 
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\Test\XML\BooleanElement;
+use SimpleSAML\XML\AbstractElement;
+use SimpleSAML\XML\BooleanElementTrait;
 use SimpleSAML\XML\DOMDocumentFactory;
 use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
 
@@ -15,12 +18,11 @@
 /**
  * Class \SimpleSAML\XML\BooleanElementTraitTest
  *
- * @covers \SimpleSAML\XML\TestUtils\SerializableElementTestTrait
- * @covers \SimpleSAML\XML\BooleanElementTrait
- * @covers \SimpleSAML\XML\AbstractElement
- *
  * @package simplesamlphp\xml-common
  */
+#[CoversClass(SerializableElementTestTrait::class)]
+#[CoversClass(BooleanElementTrait::class)]
+#[CoversClass(AbstractElement::class)]
 final class BooleanElementTraitTest extends TestCase
 {
     use SerializableElementTestTrait;
diff --git a/tests/XML/ChunkTest.php b/tests/XML/ChunkTest.php
index c413adc..5893b0c 100644
--- a/tests/XML/ChunkTest.php
+++ b/tests/XML/ChunkTest.php
@@ -4,6 +4,7 @@
 
 namespace SimpleSAML\Test\XML;
 
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\XML\Chunk;
 use SimpleSAML\XML\DOMDocumentFactory;
@@ -16,11 +17,10 @@
 /**
  * Class \SimpleSAML\XML\ChunkTest
  *
- * @covers \SimpleSAML\XML\TestUtils\SerializableElementTestTrait
- * @covers \SimpleSAML\XML\Chunk
- *
  * @package simplesamlphp\xml-common
  */
+#[CoversClass(SerializableElementTestTrait::class)]
+#[CoversClass(Chunk::class)]
 final class ChunkTest extends TestCase
 {
     use SerializableElementTestTrait;
diff --git a/tests/XML/DOMDocumentFactoryTest.php b/tests/XML/DOMDocumentFactoryTest.php
index 9c01396..2e01f03 100644
--- a/tests/XML/DOMDocumentFactoryTest.php
+++ b/tests/XML/DOMDocumentFactoryTest.php
@@ -4,6 +4,8 @@
 
 namespace SimpleSAML\Test\XML;
 
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\Group;
 use PHPUnit\Framework\TestCase;
 use RuntimeException;
 use SimpleSAML\Assert\AssertionFailedException;
@@ -13,14 +15,12 @@
 use function strval;
 
 /**
- * @covers \SimpleSAML\XML\DOMDocumentFactory
  * @package simplesamlphp\xml-common
  */
+#[CoversClass(DOMDocumentFactory::class)]
+#[Group('domdocument')]
 final class DOMDocumentFactoryTest extends TestCase
 {
-    /**
-     * @group domdocument
-     */
     public function testNotXmlStringRaisesAnException(): void
     {
         $this->expectException(UnparseableXMLException::class);
@@ -28,9 +28,6 @@ public function testNotXmlStringRaisesAnException(): void
     }
 
 
-    /**
-     * @group domdocument
-     */
     public function testXmlStringIsCorrectlyLoaded(): void
     {
         $xml = '<root/>';
@@ -41,8 +38,6 @@ public function testXmlStringIsCorrectlyLoaded(): void
     }
 
 
-    /**
-     */
     public function testFileThatDoesNotExistIsNotAccepted(): void
     {
         $this->expectException(RuntimeException::class);
@@ -51,9 +46,6 @@ public function testFileThatDoesNotExistIsNotAccepted(): void
     }
 
 
-    /**
-     * @group domdocument
-     */
     public function testFileThatDoesNotContainXMLCannotBeLoaded(): void
     {
         $this->expectException(RuntimeException::class);
@@ -61,9 +53,6 @@ public function testFileThatDoesNotContainXMLCannotBeLoaded(): void
     }
 
 
-    /**
-     * @group domdocument
-     */
     public function testFileWithValidXMLCanBeLoaded(): void
     {
         $file = 'resources/xml/domdocument_valid_xml.xml';
@@ -73,9 +62,6 @@ public function testFileWithValidXMLCanBeLoaded(): void
     }
 
 
-    /**
-     * @group domdocument
-     */
     public function testFileThatContainsDocTypeIsNotAccepted(): void
     {
         $file = 'resources/xml/domdocument_doctype.xml';
@@ -87,9 +73,6 @@ public function testFileThatContainsDocTypeIsNotAccepted(): void
     }
 
 
-    /**
-     * @group domdocument
-     */
     public function testStringThatContainsDocTypeIsNotAccepted(): void
     {
         $xml = '<!DOCTYPE foo [<!ELEMENT foo ANY > <!ENTITY xxe SYSTEM "file:///dev/random" >]><foo />';
@@ -101,9 +84,6 @@ public function testStringThatContainsDocTypeIsNotAccepted(): void
     }
 
 
-    /**
-     * @group domdocument
-     */
     public function testEmptyFileIsNotValid(): void
     {
         $file = 'resources/xml/domdocument_empty.xml';
@@ -113,9 +93,6 @@ public function testEmptyFileIsNotValid(): void
     }
 
 
-    /**
-     * @group                    domdocument
-     */
     public function testEmptyStringIsNotValid(): void
     {
         $this->expectException(AssertionFailedException::class);
diff --git a/tests/XML/Exception/IOExceptionTest.php b/tests/XML/Exception/IOExceptionTest.php
index 6aec975..6fd7887 100644
--- a/tests/XML/Exception/IOExceptionTest.php
+++ b/tests/XML/Exception/IOExceptionTest.php
@@ -4,6 +4,7 @@
 
 namespace SimpleSAML\Test\XML;
 
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\XML\Exception\IOException;
 
@@ -11,9 +12,8 @@
  * Empty shell class for testing IOException.
  *
  * @package simplesaml/xml-security
- *
- * @covers \SimpleSAML\XML\Exception\IOException
  */
+#[CoversClass(IOException::class)]
 final class IOExceptionTest extends TestCase
 {
     /**
diff --git a/tests/XML/Exception/UnparseableXMLExceptionTest.php b/tests/XML/Exception/UnparseableXMLExceptionTest.php
index 557d004..7f3f1de 100644
--- a/tests/XML/Exception/UnparseableXMLExceptionTest.php
+++ b/tests/XML/Exception/UnparseableXMLExceptionTest.php
@@ -5,6 +5,7 @@
 namespace SimpleSAML\Test\XML;
 
 use LibXMLError;
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\XML\Exception\UnparseableXMLException;
 
@@ -12,9 +13,8 @@
  * Empty shell class for testing UnparseableXMLException.
  *
  * @package simplesaml/xml-security
- *
- * @covers \SimpleSAML\XML\Exception\UnparseableXMLException
  */
+#[CoversClass(UnparseableXMLException::class)]
 final class UnparseableXMLExceptionTest extends TestCase
 {
     /** @var \LibXMLError $libxmlerror */
diff --git a/tests/XML/ExtendableAttributesTest.php b/tests/XML/ExtendableAttributesTest.php
index 2cfe820..17603f4 100644
--- a/tests/XML/ExtendableAttributesTest.php
+++ b/tests/XML/ExtendableAttributesTest.php
@@ -4,6 +4,7 @@
 
 namespace SimpleSAML\Test\XML;
 
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\Test\XML\ExtendableAttributesElement;
 use SimpleSAML\XML\Attribute;
@@ -16,11 +17,10 @@
 /**
  * Class \SimpleSAML\XML\ExtendableAttributesTest
  *
- * @covers \SimpleSAML\XML\TestUtils\SchemaValidationTestTrait
- * @covers \SimpleSAML\XML\TestUtils\SerializableElementTestTrait
- *
  * @package simplesamlphp\xml-common
  */
+#[CoversClass(SchemaValidationTestTrait::class)]
+#[CoversClass(SerializableElementTestTrait::class)]
 final class ExtendableAttributesTest extends TestCase
 {
     use SchemaValidationTestTrait;
diff --git a/tests/XML/ExtendableAttributesTraitTest.php b/tests/XML/ExtendableAttributesTraitTest.php
index a6178b6..725c35e 100644
--- a/tests/XML/ExtendableAttributesTraitTest.php
+++ b/tests/XML/ExtendableAttributesTraitTest.php
@@ -4,21 +4,24 @@
 
 namespace SimpleSAML\Test\XML;
 
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\Assert\AssertionFailedException;
 use SimpleSAML\Test\XML\ExtendableAttributesElement;
 use SimpleSAML\XML\Attribute;
+use SimpleSAML\XML\ExtendableAttributesTrait;
+use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
+use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
 use SimpleSAML\XML\XsNamespace as NS;
 
 /**
  * Class \SimpleSAML\XML\ExtendableAttributesTraitTest
  *
- * @covers \SimpleSAML\XML\TestUtils\SchemaValidationTestTrait
- * @covers \SimpleSAML\XML\TestUtils\SerializableElementTestTrait
- * @covers \SimpleSAML\XML\ExtendableAttributesTrait
- *
  * @package simplesamlphp\xml-common
  */
+#[CoversClass(SchemaValidationTestTrait::class)]
+#[CoversClass(SerializableElementTestTrait::class)]
+#[CoversClass(ExtendableAttributesTrait::class)]
 final class ExtendableAttributesTraitTest extends TestCase
 {
     /** @var \SimpleSAML\XML\Attribute */
diff --git a/tests/XML/ExtendableElementTest.php b/tests/XML/ExtendableElementTest.php
index 5cf1073..9d09ca1 100644
--- a/tests/XML/ExtendableElementTest.php
+++ b/tests/XML/ExtendableElementTest.php
@@ -4,6 +4,7 @@
 
 namespace SimpleSAML\Test\XML;
 
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\XML\Chunk;
 use SimpleSAML\XML\DOMDocumentFactory;
@@ -16,11 +17,10 @@
 /**
  * Class \SimpleSAML\XML\ExtendableElementTest
  *
- * @covers \SimpleSAML\XML\TestUtils\SchemaValidationTestTrait
- * @covers \SimpleSAML\XML\TestUtils\SerializableElementTestTrait
- *
  * @package simplesamlphp\xml-common
  */
+#[CoversClass(SchemaValidationTestTrait::class)]
+#[CoversClass(SerializableElementTestTrait::class)]
 final class ExtendableElementTest extends TestCase
 {
     use SchemaValidationTestTrait;
diff --git a/tests/XML/ExtendableElementTraitTest.php b/tests/XML/ExtendableElementTraitTest.php
index 8c40b44..ea09589 100644
--- a/tests/XML/ExtendableElementTraitTest.php
+++ b/tests/XML/ExtendableElementTraitTest.php
@@ -4,23 +4,26 @@
 
 namespace SimpleSAML\Test\XML;
 
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\Assert\AssertionFailedException;
 use SimpleSAML\Test\XML\ExtendableElement;
 use SimpleSAML\XML\Chunk;
 use SimpleSAML\XML\DOMDocumentFactory;
 use SimpleSAML\XML\ElementInterface;
+use SimpleSAML\XML\ExtendableElementTrait;
+use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
+use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
 use SimpleSAML\XML\XsNamespace as NS;
 
 /**
  * Class \SimpleSAML\XML\ExtendableElementTraitTest
  *
- * @covers \SimpleSAML\XML\TestUtils\SchemaValidationTestTrait
- * @covers \SimpleSAML\XML\TestUtils\SerializableElementTestTrait
- * @covers \SimpleSAML\XML\ExtendableElementTrait
- *
  * @package simplesamlphp\xml-common
  */
+#[CoversClass(SchemaValidationTestTrait::class)]
+#[CoversClass(SerializableElementTestTrait::class)]
+#[CoversClass(ExtendableElementTrait::class)]
 final class ExtendableElementTraitTest extends TestCase
 {
     /** @var \SimpleSAML\XML\SerializableElementInterface */
diff --git a/tests/XML/LocalizedStringElementTraitTest.php b/tests/XML/LocalizedStringElementTraitTest.php
index c4198ad..4266630 100644
--- a/tests/XML/LocalizedStringElementTraitTest.php
+++ b/tests/XML/LocalizedStringElementTraitTest.php
@@ -4,9 +4,12 @@
 
 namespace SimpleSAML\Test\XML;
 
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\Test\XML\LocalizedStringElement;
+use SimpleSAML\XML\AbstractElement;
 use SimpleSAML\XML\DOMDocumentFactory;
+use SimpleSAML\XML\LocalizedStringElementTrait;
 use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
 
 use function dirname;
@@ -15,12 +18,11 @@
 /**
  * Class \SimpleSAML\XML\LocalizedStringElementTraitTest
  *
- * @covers \SimpleSAML\XML\TestUtils\SerializableElementTestTrait
- * @covers \SimpleSAML\XML\LocalizedStringElementTrait
- * @covers \SimpleSAML\XML\AbstractElement
- *
  * @package simplesamlphp\xml-common
  */
+#[CoversClass(SerializableElementTestTrait::class)]
+#[CoversClass(LocalizedStringElementTrait::class)]
+#[CoversClass(AbstractElement::class)]
 final class LocalizedStringElementTraitTest extends TestCase
 {
     use SerializableElementTestTrait;
diff --git a/tests/XML/QNameElementTraitTest.php b/tests/XML/QNameElementTraitTest.php
index f0300f6..4610efe 100644
--- a/tests/XML/QNameElementTraitTest.php
+++ b/tests/XML/QNameElementTraitTest.php
@@ -4,9 +4,11 @@
 
 namespace SimpleSAML\Test\XML;
 
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\XML\DOMDocumentFactory;
 use SimpleSAML\XML\Exception\SchemaViolationException;
+use SimpleSAML\XML\QNameElementTrait;
 use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
 
 use function dirname;
@@ -15,11 +17,10 @@
 /**
  * Class \SimpleSAML\Test\XML\QNameElementTraitTest
  *
- * @covers \SimpleSAML\XML\TestUtils\SerializableElementTestTrait
- * @covers \SimpleSAML\XML\QNameElementTrait
- *
  * @package simplesamlphp\xml-common
  */
+#[CoversClass(SerializableElementTestTrait::class)]
+#[CoversClass(QNameElementTrait::class)]
 final class QNameElementTraitTest extends TestCase
 {
     use SerializableElementTestTrait;
diff --git a/tests/XML/StringElementTraitTest.php b/tests/XML/StringElementTraitTest.php
index 5b2750c..aeb66b8 100644
--- a/tests/XML/StringElementTraitTest.php
+++ b/tests/XML/StringElementTraitTest.php
@@ -4,9 +4,12 @@
 
 namespace SimpleSAML\Test\XML;
 
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\Test\XML\StringElement;
+use SimpleSAML\XML\AbstractElement;
 use SimpleSAML\XML\DOMDocumentFactory;
+use SimpleSAML\XML\StringElementTrait;
 use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
 
 use function dirname;
@@ -15,12 +18,11 @@
 /**
  * Class \SimpleSAML\XML\StringElementTraitTest
  *
- * @covers \SimpleSAML\XML\TestUtils\SerializableElementTestTrait
- * @covers \SimpleSAML\XML\StringElementTrait
- * @covers \SimpleSAML\XML\AbstractElement
- *
  * @package simplesamlphp\xml-common
  */
+#[CoversClass(SerializableElementTestTrait::class)]
+#[CoversClass(StringElementTrait::class)]
+#[CoversClass(AbstractElement::class)]
 final class StringElementTraitTest extends TestCase
 {
     use SerializableElementTestTrait;
diff --git a/tests/XML/URIElementTraitTest.php b/tests/XML/URIElementTraitTest.php
index be7f4bb..55094f7 100644
--- a/tests/XML/URIElementTraitTest.php
+++ b/tests/XML/URIElementTraitTest.php
@@ -4,10 +4,13 @@
 
 namespace SimpleSAML\Test\XML;
 
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\Test\XML\URIElement;
+use SimpleSAML\XML\AbstractElement;
 use SimpleSAML\XML\DOMDocumentFactory;
 use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\URIElementTrait;
 
 use function dirname;
 use function strval;
@@ -15,12 +18,11 @@
 /**
  * Class \SimpleSAML\XML\URIElementTraitTest
  *
- * @covers \SimpleSAML\XML\TestUtils\SerializableElementTestTrait
- * @covers \SimpleSAML\XML\URIElementTrait
- * @covers \SimpleSAML\XML\AbstractElement
- *
  * @package simplesamlphp\xml-common
  */
+#[CoversClass(SerializableElementTestTrait::class)]
+#[CoversClass(URIElementTrait::class)]
+#[CoversClass(AbstractElement::class)]
 final class URIElementTraitTest extends TestCase
 {
     use SerializableElementTestTrait;
diff --git a/tools/composer-require-checker.json b/tools/composer-require-checker.json
new file mode 100644
index 0000000..a7085db
--- /dev/null
+++ b/tools/composer-require-checker.json
@@ -0,0 +1,5 @@
+{
+  "symbol-whitelist": [
+    "PHPUnit\\Framework\\Attributes\\Depends"
+  ]
+}