diff --git a/src/XML/fed/AbstractPseudonymBasisType.php b/src/XML/fed/AbstractPseudonymBasisType.php
index da250cb0..f104d4f6 100644
--- a/src/XML/fed/AbstractPseudonymBasisType.php
+++ b/src/XML/fed/AbstractPseudonymBasisType.php
@@ -47,18 +47,6 @@ final public function __construct(
     }
 
 
-    /**
-     * Test if an object, at the state it's in, would produce an empty XML-element
-     *
-     * @return bool
-     */
-    public function isEmptyElement(): bool
-    {
-        return empty($this->getElements())
-            && empty($this->getAttributesNS());
-    }
-
-
     /**
      * Create an instance of this object from its XML representation.
      *
diff --git a/tests/WSSecurity/XML/fed/FederationMetadataHandler.php b/tests/WSSecurity/XML/fed/FederationMetadataHandlerTest.php
similarity index 100%
rename from tests/WSSecurity/XML/fed/FederationMetadataHandler.php
rename to tests/WSSecurity/XML/fed/FederationMetadataHandlerTest.php
diff --git a/tests/WSSecurity/XML/fed/ReferenceToken11Test.php b/tests/WSSecurity/XML/fed/ReferenceToken11Test.php
index 6d0b7e7b..7dd44744 100644
--- a/tests/WSSecurity/XML/fed/ReferenceToken11Test.php
+++ b/tests/WSSecurity/XML/fed/ReferenceToken11Test.php
@@ -74,4 +74,19 @@ public function testMarshalling(): void
             strval($referenceToken11),
         );
     }
+
+
+    /**
+     * Adding an empty X509lToken element should yield an empty element.
+     */
+    public function testMarshallingEmptyElement(): void
+    {
+        $fedns = C::NS_FED;
+        $referenceToken11 = new ReferenceToken11();
+        $this->assertEquals(
+            "<fed:ReferenceToken11 xmlns:fed=\"$fedns\"/>",
+            strval($referenceToken11),
+        );
+        $this->assertTrue($referenceToken11->isEmptyElement());
+    }
 }
diff --git a/tests/WSSecurity/XML/fed/ReferenceTokenTest.php b/tests/WSSecurity/XML/fed/ReferenceTokenTest.php
index 61951173..04691418 100644
--- a/tests/WSSecurity/XML/fed/ReferenceTokenTest.php
+++ b/tests/WSSecurity/XML/fed/ReferenceTokenTest.php
@@ -135,4 +135,19 @@ public function testMarshalling(): void
             strval($referenceToken)
         );
     }
+
+
+    /**
+     * Adding an empty ReferenceToken element should yield an empty element.
+     */
+    public function testMarshallingEmptyElement(): void
+    {
+        $fedns = C::NS_FED;
+        $referenceToken = new ReferenceToken();
+        $this->assertEquals(
+            "<fed:ReferenceToken xmlns:fed=\"$fedns\"/>",
+            strval($referenceToken),
+        );
+        $this->assertTrue($referenceToken->isEmptyElement());
+    }
 }
diff --git a/tests/WSSecurity/XML/fed/RelativeToTest.php b/tests/WSSecurity/XML/fed/RelativeToTest.php
index 58d620c0..4737630b 100644
--- a/tests/WSSecurity/XML/fed/RelativeToTest.php
+++ b/tests/WSSecurity/XML/fed/RelativeToTest.php
@@ -66,4 +66,19 @@ public function testMarshalling(): void
             strval($relativeTo),
         );
     }
+
+
+    /**
+     * Adding an empty RelativeTo element should yield an empty element.
+     */
+    public function testMarshallingEmptyElement(): void
+    {
+        $fedns = C::NS_FED;
+        $relativeTo = new RelativeTo();
+        $this->assertEquals(
+            "<fed:RelativeTo xmlns:fed=\"$fedns\"/>",
+            strval($relateTo),
+        );
+        $this->assertTrue($relativeTo->isEmptyElement());
+    }
 }
diff --git a/tests/WSSecurity/XML/wst/CodeTest.php b/tests/WSSecurity/XML/wst/CodeTest.php
index 136b0f18..7f952822 100644
--- a/tests/WSSecurity/XML/wst/CodeTest.php
+++ b/tests/WSSecurity/XML/wst/CodeTest.php
@@ -16,6 +16,7 @@
  * Class \SimpleSAML\WSSecurity\XML\wst\CodeTest
  *
  * @covers \SimpleSAML\WSSecurity\XML\wst\Code
+ * @covers \SimpleSAML\WSSecurity\XML\wst\AbstractStatusCodeOpenEnum
  * @covers \SimpleSAML\WSSecurity\XML\wst\AbstractWstElement
  *
  * @package tvdijen/ws-security
diff --git a/tests/WSSecurity/XML/wst/ComputedKeyTest.php b/tests/WSSecurity/XML/wst/ComputedKeyTest.php
index 75ad84c3..4b97b8b5 100644
--- a/tests/WSSecurity/XML/wst/ComputedKeyTest.php
+++ b/tests/WSSecurity/XML/wst/ComputedKeyTest.php
@@ -17,6 +17,7 @@
  * Class \SimpleSAML\WSSecurity\XML\wst\ComputedKeyTest
  *
  * @covers \SimpleSAML\WSSecurity\XML\wst\ComputedKey
+ * @covers \SimpleSAML\WSSecurity\XML\wst\AbstractComputedKeyOpenEnum
  * @covers \SimpleSAML\WSSecurity\XML\wst\AbstractWstElement
  *
  * @package tvdijen/ws-security
diff --git a/tests/WSSecurity/XML/wst/KeyTypeTest.php b/tests/WSSecurity/XML/wst/KeyTypeTest.php
index de819055..fb299252 100644
--- a/tests/WSSecurity/XML/wst/KeyTypeTest.php
+++ b/tests/WSSecurity/XML/wst/KeyTypeTest.php
@@ -17,6 +17,7 @@
  * Class \SimpleSAML\WSSecurity\XML\wst\KeyTypeTest
  *
  * @covers \SimpleSAML\WSSecurity\XML\wst\KeyType
+ * @covers \SimpleSAML\WSSecurity\XML\wst\AbstractKeyTypeOpenEnum
  * @covers \SimpleSAML\WSSecurity\XML\wst\AbstractWstElement
  *
  * @package tvdijen/ws-security
diff --git a/tests/WSSecurity/XML/wst/ParticipantsTest.php b/tests/WSSecurity/XML/wst/ParticipantsTest.php
index 544ff04d..610accc7 100644
--- a/tests/WSSecurity/XML/wst/ParticipantsTest.php
+++ b/tests/WSSecurity/XML/wst/ParticipantsTest.php
@@ -21,7 +21,7 @@
  * Class \SimpleSAML\WSSecurity\XML\wst\ParticipantsTest
  *
  * @covers \SimpleSAML\WSSecurity\XML\wst\Participants
- * @covers \SimpleSAML\WSSecurity\XML\wst\AbstractParticipantType
+ * @covers \SimpleSAML\WSSecurity\XML\wst\AbstractParticipantsType
  * @covers \SimpleSAML\WSSecurity\XML\wst\AbstractWstElement
  *
  * @package tvdijen/ws-security
@@ -66,4 +66,19 @@ public function testMarshalling(): void
             strval($participants),
         );
     }
+
+
+    /**
+     * Adding an empty Participants element should yield an empty element.
+     */
+    public function testMarshallingEmptyElement(): void
+    {
+        $fedns = C::NS_FED;
+        $participants = new Participants();
+        $this->assertEquals(
+            "<fed:Participants xmlns:fed=\"$fedns\"/>",
+            strval($participants),
+        );
+        $this->assertTrue($participants->isEmptyElement());
+    }
 }
diff --git a/tests/WSSecurity/XML/wst/SignChallengeTest.php b/tests/WSSecurity/XML/wst/SignChallengeTest.php
index cfa4c973..dcfb5a6e 100644
--- a/tests/WSSecurity/XML/wst/SignChallengeTest.php
+++ b/tests/WSSecurity/XML/wst/SignChallengeTest.php
@@ -66,4 +66,15 @@ public function testMarshalling(): void
             strval($signChallenge),
         );
     }
+
+
+    /**
+     * Test creating an empty SignChallenge object from scratch.
+     */
+    public function testMarshallingEmpty(): void
+    {
+        $signChallenge = new SignChallenge();
+
+        $this->assertTrue($signChallenge->isEmptyElement());
+    }
 }
diff --git a/tests/WSSecurity/XML/wst/StatusTest.php b/tests/WSSecurity/XML/wst/StatusTest.php
index 8c907408..e8bdf923 100644
--- a/tests/WSSecurity/XML/wst/StatusTest.php
+++ b/tests/WSSecurity/XML/wst/StatusTest.php
@@ -19,6 +19,7 @@
  * Class \SimpleSAML\WSSecurity\XML\wst\StatusTest
  *
  * @covers \SimpleSAML\WSSecurity\XML\wst\Status
+ * @covers \SimpleSAML\WSSecurity\XML\wst\AbstractStatusType
  * @covers \SimpleSAML\WSSecurity\XML\wst\AbstractWstElement
  *
  * @package tvdijen/ws-security