diff --git a/composer.lock b/composer.lock
index b04f0a2..814ca6a 100644
--- a/composer.lock
+++ b/composer.lock
@@ -63,7 +63,7 @@
             "source": {
                 "type": "git",
                 "url": "mensbeam-gitea:MensBeam/HTML-Parser.git",
-                "reference": "5495e7c81e36409bebb998962f8624b5744a1b30"
+                "reference": "afaf10d602ee04d7eba437d3a08ef10ebef4f5b0"
             },
             "require": {
                 "ext-dom": "*",
@@ -130,7 +130,7 @@
                 "parsing",
                 "whatwg"
             ],
-            "time": "2021-11-18T17:39:20+00:00"
+            "time": "2021-11-22T01:55:09+00:00"
         },
         {
             "name": "mensbeam/intl",
diff --git a/lib/Attr.php b/lib/Attr.php
index 449237d..2a14cfe 100644
--- a/lib/Attr.php
+++ b/lib/Attr.php
@@ -25,14 +25,18 @@ class Attr extends Node {
     }
 
     protected function __get_namespaceURI(): ?string {
-        $namespace = $this->innerNode->namespaceURI;
-        return (!$this->ownerDocument instanceof XMLDocument && $namespace === null) ? Node::HTML_NAMESPACE : $namespace;
+        return $this->innerNode->namespaceURI;
     }
 
-    protected function __get_ownerElement(): Element {
+    protected function __get_ownerElement(): ?Element {
         // PHP's DOM does this correctly already.
-        $wrapperNode = $this->innerNode->ownerDocument->getWrapperNode($this->innerNode->ownerElement);
-        return $wrapperNode;
+        $innerOwnerElement = $this->innerNode->ownerElement;
+
+        if ($innerOwnerElement === null) {
+            return null;
+        }
+
+        return $this->innerNode->ownerDocument->getWrapperNode($this->innerNode->ownerElement);
     }
 
     protected function __get_prefix(): string {
diff --git a/lib/DOMException.php b/lib/DOMException.php
index 08e61c3..b0211ed 100644
--- a/lib/DOMException.php
+++ b/lib/DOMException.php
@@ -18,6 +18,7 @@ class DOMException extends Exception {
     public const NO_MODIFICATION_ALLOWED = 7;
     public const NOT_FOUND = 8;
     public const NOT_SUPPORTED = 9;
+    public const IN_USE_ATTRIBUTE = 10;
     public const SYNTAX_ERROR = 12;
     public const INVALID_MODIFICATION = 13;
     public const NAMESPACE_ERROR = 14;
@@ -35,6 +36,7 @@ class DOMException extends Exception {
               7 => 'Modification not allowed here',
               8 => 'Not found error',
               9 => 'Feature is not supported',
+             10 => 'The attribute is in use',
              12 => 'Syntax error',
              13 => 'Invalid modification error',
              14 => 'Namespace error',
diff --git a/lib/Element.php b/lib/Element.php
index b936a2d..75272ee 100644
--- a/lib/Element.php
+++ b/lib/Element.php
@@ -22,16 +22,28 @@ class Element extends Node {
         return Reflection::createFromProtectedConstructor(__NAMESPACE__ . '\\NamedNodeMap', $this, ($this instanceof Document) ? $this->innerNode : $this->innerNode->ownerDocument, $this->innerNode->attributes);
     }
 
+    protected function __get_className(): string {
+        # The className attribute must reflect the "class" content attribute.
+        # Return the result of running get an attribute value given this and name.
+        return $this->getAttribute('class') ?? '';
+    }
+
+    protected function __set_className(string $value): void {
+        # The className attribute must reflect the "class" content attribute.
+        # Set an attribute value for this using name and the given value.
+        $this->setAttribute('class', $value);
+    }
+
     protected function __get_id(): string {
         # The id attribute must reflect the "id" content attribute.
         # Return the result of running get an attribute value given this and name.
         return $this->getAttribute('id') ?? '';
     }
 
-    protected function __set_id(string $value): string {
+    protected function __set_id(string $value): void {
         # The id attribute must reflect the "id" content attribute.
         # Set an attribute value for this using name and the given value.
-        return $this->setAttribute('id', $value);
+        $this->setAttribute('id', $value);
     }
 
     protected function __get_localName(): ?string {
@@ -39,14 +51,13 @@ class Element extends Node {
         return $this->innerNode->localName;
     }
 
-    protected function __get_namespaceURI(): string {
+    protected function __get_namespaceURI(): ?string {
         // PHP's DOM uses null incorrectly for the HTML namespace, and if you attempt to
         // use the HTML namespace anyway it has additional bugs we don't have to work
         // around because of the wrapper classes; So, use the null namespace internally
         // but print out the HTML namespace instead.
         $namespace = $this->innerNode->namespaceURI;
-        $doc = $this->ownerDocument;
-        return (!$doc instanceof XMLDocument && $namespace === null) ? self::HTML_NAMESPACE : $namespace;
+        return (!$this->ownerDocument instanceof XMLDocument && $namespace === null) ? self::HTML_NAMESPACE : $namespace;
     }
 
     protected function __get_prefix(): ?string {
@@ -94,42 +105,6 @@ class Element extends Node {
         return $list;
     }
 
-    public function getAttributeNodeNS(?string $namespace, string $localName): ?Attr {
-        # The getAttributeNodeNS(namespace, localName) method steps are to return the
-        # result of getting an attribute given namespace, localName, and this.
-        #
-        # To get an attribute by namespace and local name given a namespace, localName,
-        # and element element, run these steps:
-        #
-        # 1. If namespace is the empty string, then set it to null.
-        if ($namespace === '') {
-            $namespace = null;
-        }
-
-        # 2. Return the attribute in element’s attribute list whose namespace is namespace
-        #    and local name is localName, if any; otherwise null.
-        // Going to try to handle this by getting the PHP DOM to do the heavy lifting
-        // when we can because it's faster.
-        $value = $this->innerNode->getAttributeNodeNS($namespace, $localName);
-        if (!$value) {
-            // Replace any offending characters with "UHHHHHH" where H are the uppercase
-            // hexadecimal digits of the character's code point
-            $localName = $this->coerceName($localName);
-
-            // The PHP DOM does not acknowledge the presence of XMLNS-namespace attributes
-            // sometimes, too... so this will get those as well in those circumstances.
-            $attributes = $this->innerNode->attributes;
-            foreach ($attributes as $a) {
-                if ($a->namespaceURI === $namespace && $a->localName === $localName) {
-                    return $this->innerNode->ownerDocument->getWrapperNode($a);
-                }
-            }
-            return null;
-        }
-
-        return ($value !== false) ? $this->innerNode->ownerDocument->getWrapperNode($value) : null;
-    }
-
     public function getAttributeNode(string $qualifiedName): ?Attr {
         # The getAttributeNode(qualifiedName) method steps are to return the result of
         # getting an attribute given qualifiedName and this.
@@ -139,31 +114,56 @@ class Element extends Node {
         #
         # 1. If element is in the HTML namespace and its node document is an HTML document,
         #    then set qualifiedName to qualifiedName in ASCII lowercase.
-        // Document will always be an HTML document
         if (!$this instanceof XMLDocument && $this->namespaceURI === self::HTML_NAMESPACE) {
             $qualifiedName = strtolower($qualifiedName);
         }
 
+        $qualifiedName = $this->coerceName($qualifiedName);
+
         # 2. Return the first attribute in element’s attribute list whose qualified name is
         #    qualifiedName; otherwise null.
-        // Going to try to handle this by getting the PHP DOM to do the heavy lifting
-        // when we can because it's faster.
-        $attr = $this->innerNode->getAttributeNode($qualifiedName);
-        if ($attr === false) {
-            // Replace any offending characters with "UHHHHHH" where H are the uppercase
-            // hexadecimal digits of the character's code point
-            $qualifiedName = $this->coerceName($qualifiedName);
+        // Manually going through the attributes because PHP DOM has issues, returning
+        // odd "DOMNamespaceNode" objects sometimes instead of the actual attributes...
+        // yeah...
+        $attributes = $this->innerNode->attributes;
+        foreach ($attributes as $attr) {
+            if ($attr->nodeName === $qualifiedName) {
+                return $this->innerNode->ownerDocument->getWrapperNode($attr);
+            }
+        }
 
-            $attributes = $this->innerNode->attributes;
-            foreach ($attributes as $a) {
-                if ($a->nodeName === $qualifiedName) {
-                    return $this->innerNode->ownerDocument->getWrapperNode($a);
-                }
+        return null;
+    }
+
+    public function getAttributeNodeNS(?string $namespace, string $localName): ?Attr {
+        static $count = 0;
+        $count++;
+        # The getAttributeNodeNS(namespace, localName) method steps are to return the
+        # result of getting an attribute given namespace, localName, and this.
+        #
+        # To get an attribute by namespace and local name given a namespace, localName,
+        # and element element, run these steps:
+        #
+        # 1. If namespace is the empty string, then set it to null.
+        if ($namespace === '') {
+            $namespace = null;
+        }
+
+        $localName = $this->coerceName($localName);
+
+        # 2. Return the attribute in element’s attribute list whose namespace is namespace
+        #    and local name is localName, if any; otherwise null.
+        // Manually going through the attributes because PHP DOM has issues, returning
+        // odd "DOMNamespaceNode" objects sometimes instead of the actual attributes...
+        // yeah...
+        $attributes = $this->innerNode->attributes;
+        foreach ($attributes as $attr) {
+            if ($attr->namespaceURI === $namespace && $attr->localName === $localName) {
+                return $this->innerNode->ownerDocument->getWrapperNode($attr);
             }
-            return null;
         }
 
-        return ($attr !== false) ? $this->innerNode->ownerDocument->getWrapperNode($attr) : null;
+        return null;
     }
 
     public function getAttributeNS(?string $namespace, string $localName): ?string {
@@ -183,13 +183,6 @@ class Element extends Node {
         return $attr->value;
     }
 
-    public function hasAttributes(): bool {
-        # The hasAttributes() method steps are to return false if this’s attribute list
-        # is empty; otherwise true.
-        // PHP's DOM does this correctly already.
-        return $this->innerNode->hasAttributes();
-    }
-
     public function hasAttribute(string $qualifiedName): bool {
         # The hasAttribute(qualifiedName) method steps are:
         #
@@ -215,16 +208,47 @@ class Element extends Node {
         return $value;
     }
 
+    public function hasAttributeNS(?string $namespace, string $localName): bool {
+        # The hasAttributeNS(namespace, localName) method steps are:
+        #
+        # 1. If namespace is the empty string, then set it to null.
+        if ($namespace === '') {
+            $namespace = null;
+        }
+
+        # 2. Return true if this has an attribute whose namespace is namespace and local
+        #    name is localName; otherwise false.
+        # An element has an attribute A if its attribute list contains A.
+        // Going to try to handle this by getting the PHP DOM to do the heavy lifting
+        // when we can because it's faster.
+        $value = $this->innerNode->hasAttributeNS($namespace, $localName);
+        if (!$value) {
+            // PHP DOM does not acknowledge the presence of XMLNS-namespace attributes,
+            // so try it again just in case; getAttributeNode will coerce names if
+            // necessary, too.
+            $value = ($this->getAttributeNodeNS($namespace, $localName) !== null);
+        }
+
+        return $value;
+    }
+
+    public function hasAttributes(): bool {
+        # The hasAttributes() method steps are to return false if this’s attribute list
+        # is empty; otherwise true.
+        // PHP's DOM does this correctly already.
+        return $this->innerNode->hasAttributes();
+    }
+
     public function setAttribute(string $qualifiedName, string $value): void {
         # 1. If qualifiedName does not match the Name production in XML, then throw an
         #    "InvalidCharacterError" DOMException.
-        if (preg_match(InnerDocument::NAME_PRODUCTION_REGEX, $qualifiedName) !== 1) {
+        if (!preg_match(InnerDocument::NAME_PRODUCTION_REGEX, $qualifiedName)) {
             throw new DOMException(DOMException::INVALID_CHARACTER);
         }
 
         # 2. If this is in the HTML namespace and its node document is an HTML document,
         #    then set qualifiedName to qualifiedName in ASCII lowercase.
-        if (!$this instanceof XMLDocument) {
+        if (!$this->ownerDocument instanceof XMLDocument && $this->namespaceURI === Node::HTML_NAMESPACE) {
             $qualifiedName = strtolower($qualifiedName);
         }
 
@@ -253,20 +277,41 @@ class Element extends Node {
     }
 
     public function setAttributeNode(Attr $attr): ?Attr {
-        $innerNode = $this->innerNode;
-        $innerAttr = $this->getInnerNode($attr);
-
         # The setAttributeNode(attr) and setAttributeNodeNS(attr) methods steps are to
         # return the result of setting an attribute given attr and this.
-        $this->innerNode->setAttributeNode($innerAttr);
+        #
+        # To set an attribute given an attr and element, run these steps:
+        #
+        # 1. If attr’s element is neither null nor element, throw an
+        #    "InUseAttributeError" DOMException.
+        $ownerElement = $attr->ownerElement;
+        if ($ownerElement !== null && $ownerElement !== $this) {
+            throw new DOMException(DOMException::IN_USE_ATTRIBUTE);
+        }
 
-        // If you create an id attribute it won't be used by PHP in getElementById, so
-        // let's fix that.
-        if ($innerAttr->namespaceURI === null && $innerAttr->localName === 'id') {
-            $innerNode->setIdAttributeNode($attr, true);
+        // PHP's DOM doesn't do this method correctly. It returns the old node if it is
+        // replaced and null otherwise. It's always supposed to return a node.
+
+        $oldAttr = $this->getAttributeNodeNS($attr->namespaceURI, $attr->localName);
+
+        # 3. If oldAttr is attr, return attr.
+        if ($oldAttr === $attr) {
+            return $attr;
         }
 
-        return $attr;
+        # 4. If oldAttr is non-null, then replace oldAttr with attr.
+        if ($oldAttr !== null) {
+            $this->innerNode->setAttributeNode($this->getInnerNode($attr));
+            return $attr;
+        }
+        # 5. Otherwise, append attr to element.
+        else {
+            $this->innerNode->appendChild($this->getInnerNode($attr));
+            return $attr;
+        }
+
+        # 6. Return oldAttr.
+        return $oldAttr;
     }
 
     public function setAttributeNodeNS(Attr $attr): ?Attr {
@@ -277,10 +322,25 @@ class Element extends Node {
         # 1. Let namespace, prefix, and localName be the result of passing namespace and
         #    qualifiedName to validate and extract.
         [ 'namespace' => $namespace, 'prefix' => $prefix, 'localName' => $localName ] = $this->validateAndExtract($qualifiedName, $namespace);
+
+        $prefix = ($prefix === null) ? null : $this->coerceName($prefix);
+        $localName = $this->coerceName($localName);
         $qualifiedName = ($prefix === null || $prefix === '') ? $localName : "{$prefix}:{$localName}";
 
         # 2. Set an attribute value for this using localName, value, and also prefix and
         #    namespace.
+        // NOTE: We create attribute nodes so that xmlns attributes don't get lost;
+        // otherwise they cannot be serialized
+        if ($namespace === self::XMLNS_NAMESPACE) {
+            $attr = $this->ownerDocument->createAttributeNS($namespace, $qualifiedName);
+            $attr->value = $this->escapeString($value, true);
+            $this->setAttributeNodeNS($attr);
+        } else {
+            $this->innerNode->setAttributeNS($namespace, $qualifiedName, $value);
+        }
+
+        /*# 2. Set an attribute value for this using localName, value, and also prefix and
+        #    namespace.
         // Going to try to handle this by getting the PHP DOM to do the heavy lifting
         // when we can because it's faster.
         // NOTE: We create attribute nodes so that xmlns attributes don't get lost;
@@ -310,14 +370,12 @@ class Element extends Node {
 
                 $this->innerNode->setAttributeNS($namespace, $qualifiedName, $value);
             }
-        }
+        }*/
 
-        if ($namespace === null) {
-            // If you create an id attribute this way it won't be used by PHP in
-            // getElementById, so let's fix that.
-            if ($qualifiedName === 'id') {
-                $this->innerNode->setIdAttribute($qualifiedName, true);
-            }
+        // If you create an id attribute this way it won't be used by PHP in
+        // getElementById, so let's fix that.
+        if ($namespace === null && $qualifiedName === 'id') {
+            $this->innerNode->setIdAttribute($qualifiedName, true);
         }
     }
 }
\ No newline at end of file
diff --git a/tests/cases/TestElement.php b/tests/cases/TestElement.php
index b016958..9ed00e5 100644
--- a/tests/cases/TestElement.php
+++ b/tests/cases/TestElement.php
@@ -121,7 +121,7 @@ class TestElement extends \PHPUnit\Framework\TestCase {
      * @covers \MensBeam\HTML\DOM\Inner\Reflection::getProtectedProperty
      */
     public function testMethod_getAttributeNS() {
-        $d = new Document('<!DOCTYPE html><html><head></head><body><svg xmlns="' . Node::SVG_NAMESPACE . '" xmlns:xlink="' . Node::XLINK_NAMESPACE . '" viewBox="0 0 42 42"></svg></body></html>');
+        $d = new Document('<!DOCTYPE html><html><head></head><body><svg xmlns="' . Node::SVG_NAMESPACE . '" xmlns:xlink="' . Node::XLINK_NAMESPACE . '" viewBox="0 0 42 42"></svg></body></html>', 'UTF-8');
         $svg = $d->getElementsByTagNameNS(Node::SVG_NAMESPACE, 'svg')[0];
         // Parser per the spec doesn't parse xmlns prefixed attributes except xlink, so let's add one manually instead to test coercion.
         $svg->setAttributeNS(Node::XMLNS_NAMESPACE, 'xmlns:poop💩', 'https://poop💩.poop');
@@ -137,4 +137,419 @@ class TestElement extends \PHPUnit\Framework\TestCase {
         // empty string namespace
         $this->assertSame('0 0 42 42', $svg->getAttributeNS('', 'viewBox'));
     }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\Element::hasAttribute
+     *
+     * @covers \MensBeam\HTML\DOM\Collection::__construct
+     * @covers \MensBeam\HTML\DOM\Collection::item
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::__get_documentElement
+     * @covers \MensBeam\HTML\DOM\Document::load
+     * @covers \MensBeam\HTML\DOM\DocumentOrElement::getElementsByTagNameNS
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__get_namespaceURI
+     * @covers \MensBeam\HTML\DOM\Element::getAttributeNode
+     * @covers \MensBeam\HTML\DOM\HTMLCollection::item
+     * @covers \MensBeam\HTML\DOM\HTMLCollection::offsetGet
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__get_ownerDocument
+     * @covers \MensBeam\HTML\DOM\Node::getInnerDocument
+     * @covers \MensBeam\HTML\DOM\Node::hasChildNodes
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__get_wrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     */
+    public function testMethod_hasAttribute() {
+        $d = new Document('<!DOCTYPE html><html id="ook" poop💩="jeff"></html>', 'UTF-8');
+        $documentElement = $d->documentElement;
+        $svg = $d->getElementsByTagNameNS(Node::SVG_NAMESPACE, 'svg')[0];
+
+        $this->assertTrue($documentElement->hasAttribute('id'));
+        $this->assertTrue($documentElement->hasAttribute('poop💩'));
+    }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\Element::hasAttributeNS
+     *
+     * @covers \MensBeam\HTML\DOM\Attr::__set_value
+     * @covers \MensBeam\HTML\DOM\Collection::__construct
+     * @covers \MensBeam\HTML\DOM\Collection::item
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::__get_documentElement
+     * @covers \MensBeam\HTML\DOM\Document::createAttributeNS
+     * @covers \MensBeam\HTML\DOM\Document::load
+     * @covers \MensBeam\HTML\DOM\DocumentOrElement::getElementsByTagNameNS
+     * @covers \MensBeam\HTML\DOM\DocumentOrElement::validateAndExtract
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__construct
+     * @covers \MensBeam\HTML\DOM\Element::getAttributeNodeNS
+     * @covers \MensBeam\HTML\DOM\Element::setAttributeNode
+     * @covers \MensBeam\HTML\DOM\Element::setAttributeNodeNS
+     * @covers \MensBeam\HTML\DOM\Element::setAttributeNS
+     * @covers \MensBeam\HTML\DOM\HTMLCollection::item
+     * @covers \MensBeam\HTML\DOM\HTMLCollection::offsetGet
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__get_ownerDocument
+     * @covers \MensBeam\HTML\DOM\Node::getInnerDocument
+     * @covers \MensBeam\HTML\DOM\Node::getInnerNode
+     * @covers \MensBeam\HTML\DOM\Node::hasChildNodes
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__get_wrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::getProtectedProperty
+     */
+    public function testMethod_hasAttributeNS() {
+        $d = new Document('<!DOCTYPE html><html><head></head><body><svg xmlns="' . Node::SVG_NAMESPACE . '" xmlns:xlink="' . Node::XLINK_NAMESPACE . '" viewBox="0 0 42 42"></svg></body></html>', 'UTF-8');
+        $svg = $d->getElementsByTagNameNS(Node::SVG_NAMESPACE, 'svg')[0];
+        // Parser per the spec doesn't parse xmlns prefixed attributes except xlink, so let's add one manually instead to test coercion.
+        $svg->setAttributeNS(Node::XMLNS_NAMESPACE, 'xmlns:poop💩', 'https://poop💩.poop');
+
+        // xmlns attribute
+        $this->assertTrue($svg->hasAttributeNS(Node::XMLNS_NAMESPACE, 'xmlns'));
+        // xmlns xlink attribute
+        $this->assertTrue($svg->hasAttributeNS(Node::XMLNS_NAMESPACE, 'xlink'));
+        // coerced namespaced attribute
+        $this->assertTrue($svg->hasAttributeNS(Node::XMLNS_NAMESPACE, 'poop💩'));
+        // nonexistent namespaced attribute
+        $this->assertFalse($svg->hasAttributeNS(Node::XMLNS_NAMESPACE, 'ook'));
+        // empty string namespace
+        $this->assertTrue($svg->hasAttributeNS('', 'viewBox'));
+    }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\Element::hasAttributes
+     *
+     * @covers \MensBeam\HTML\DOM\Collection::__construct
+     * @covers \MensBeam\HTML\DOM\Collection::item
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::load
+     * @covers \MensBeam\HTML\DOM\DocumentOrElement::getElementsByTagNameNS
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__construct
+     * @covers \MensBeam\HTML\DOM\HTMLCollection::item
+     * @covers \MensBeam\HTML\DOM\HTMLCollection::offsetGet
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Node::getInnerDocument
+     * @covers \MensBeam\HTML\DOM\Node::hasChildNodes
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     */
+    public function testMethod_hasAttributes() {
+        $d = new Document('<!DOCTYPE html><html><body><svg xmlns="' . Node::SVG_NAMESPACE . '" xmlns:xlink="' . Node::XLINK_NAMESPACE . '"></svg></body></html>', 'UTF-8');
+        $svg = $d->getElementsByTagNameNS(Node::SVG_NAMESPACE, 'svg')[0];
+        $this->assertTrue($svg->hasAttributes());
+    }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\Element::setAttribute
+     *
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::__get_documentElement
+     * @covers \MensBeam\HTML\DOM\Document::createElement
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__get_namespaceURI
+     * @covers \MensBeam\HTML\DOM\Element::getAttributeNode
+     * @covers \MensBeam\HTML\DOM\Element::hasAttribute
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__get_ownerDocument
+     * @covers \MensBeam\HTML\DOM\Node::appendChild
+     * @covers \MensBeam\HTML\DOM\Node::getInnerDocument
+     * @covers \MensBeam\HTML\DOM\Node::getInnerNode
+     * @covers \MensBeam\HTML\DOM\Node::getRootNode
+     * @covers \MensBeam\HTML\DOM\Node::postInsertionBugFixes
+     * @covers \MensBeam\HTML\DOM\Node::preInsertionBugFixes
+     * @covers \MensBeam\HTML\DOM\Node::preInsertionValidity
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__get_wrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::getProtectedProperty
+     */
+    public function testMethod_setAttribute() {
+        $d = new Document();
+        $d->appendChild($d->createElement('html'));
+        $documentElement = $d->documentElement;
+        // Just need to test coerced attributes; everything else has been covered
+        // elsewhere
+        $documentElement->setAttribute('poop💩', 'jeff');
+        $this->assertTrue($documentElement->hasAttribute('poop💩'));
+    }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\Element::setAttribute
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::__get_documentElement
+     * @covers \MensBeam\HTML\DOM\Document::createElement
+     * @covers \MensBeam\HTML\DOM\DOMException::__construct
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Node::appendChild
+     * @covers \MensBeam\HTML\DOM\Node::getInnerDocument
+     * @covers \MensBeam\HTML\DOM\Node::getInnerNode
+     * @covers \MensBeam\HTML\DOM\Node::getRootNode
+     * @covers \MensBeam\HTML\DOM\Node::postInsertionBugFixes
+     * @covers \MensBeam\HTML\DOM\Node::preInsertionBugFixes
+     * @covers \MensBeam\HTML\DOM\Node::preInsertionValidity
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::getProtectedProperty
+     */
+    public function testMethod_setAttribute_errors() {
+        $this->expectException(DOMException::class);
+        $this->expectExceptionCode(DOMException::INVALID_CHARACTER);
+        $d = new Document();
+        $d->appendChild($d->createElement('html'));
+        $d->documentElement->setAttribute('this will fail', 'fail');
+    }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\Element::setAttributeNode
+     * @covers \MensBeam\HTML\DOM\Attr::__get_localName
+     * @covers \MensBeam\HTML\DOM\Attr::__get_ownerElement
+     * @covers \MensBeam\HTML\DOM\Attr::__get_value
+     * @covers \MensBeam\HTML\DOM\Attr::__set_value
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::__get_documentElement
+     * @covers \MensBeam\HTML\DOM\Document::createAttribute
+     * @covers \MensBeam\HTML\DOM\Document::createElement
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__get_namespaceURI
+     * @covers \MensBeam\HTML\DOM\Element::getAttribute
+     * @covers \MensBeam\HTML\DOM\Element::getAttributeNode
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__get_ownerDocument
+     * @covers \MensBeam\HTML\DOM\Node::appendChild
+     * @covers \MensBeam\HTML\DOM\Node::getInnerDocument
+     * @covers \MensBeam\HTML\DOM\Node::getInnerNode
+     * @covers \MensBeam\HTML\DOM\Node::getRootNode
+     * @covers \MensBeam\HTML\DOM\Node::postInsertionBugFixes
+     * @covers \MensBeam\HTML\DOM\Node::preInsertionBugFixes
+     * @covers \MensBeam\HTML\DOM\Node::preInsertionValidity
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__get_wrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::getProtectedProperty
+     */
+    public function testMethod_setAttributeNode() {
+        $d = new Document();
+        $d->appendChild($d->createElement('html'));
+        $documentElement = $d->documentElement;
+        $attr = $d->createAttribute('poop💩');
+        $attr->value = 'jeff';
+        $documentElement->setAttributeNode($attr);
+
+        // Almost everything is covered. Just need to test same attributes and
+        // replacements.
+        $documentElement->setAttributeNode($attr);
+        $this->assertSame('jeff', $documentElement->getAttribute('poop💩'));
+        $attr = $d->createAttribute('poop💩');
+        $attr->value = 'jeff';
+        $documentElement->setAttributeNode($attr);
+        $this->assertSame('jeff', $documentElement->getAttribute('poop💩'));
+    }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\Element::setAttributeNode
+     *
+     * @covers \MensBeam\HTML\DOM\Attr::__get_localName
+     * @covers \MensBeam\HTML\DOM\Attr::__get_ownerElement
+     * @covers \MensBeam\HTML\DOM\Attr::__set_value
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::__get_documentElement
+     * @covers \MensBeam\HTML\DOM\Document::createAttribute
+     * @covers \MensBeam\HTML\DOM\Document::createElement
+     * @covers \MensBeam\HTML\DOM\DOMException::__construct
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__get_namespaceURI
+     * @covers \MensBeam\HTML\DOM\Element::getAttributeNode
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__get_ownerDocument
+     * @covers \MensBeam\HTML\DOM\Node::appendChild
+     * @covers \MensBeam\HTML\DOM\Node::getInnerDocument
+     * @covers \MensBeam\HTML\DOM\Node::getInnerNode
+     * @covers \MensBeam\HTML\DOM\Node::getRootNode
+     * @covers \MensBeam\HTML\DOM\Node::postInsertionBugFixes
+     * @covers \MensBeam\HTML\DOM\Node::preInsertionBugFixes
+     * @covers \MensBeam\HTML\DOM\Node::preInsertionValidity
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__get_wrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::getProtectedProperty
+     */
+    public function testMethod_setAttributeNode_errors() {
+        $this->expectException(DOMException::class);
+        $this->expectExceptionCode(DOMException::IN_USE_ATTRIBUTE);
+        $d = new Document();
+        $documentElement = $d->appendChild($d->createElement('html'));
+        $body = $documentElement->appendChild($d->createElement('body'));
+        $attr = $d->createAttribute('ook');
+        $attr->value = 'eek';
+        $body->setAttributeNode($attr);
+        $documentElement->setAttributeNode($attr);
+    }
+
+    /**
+     * @covers \MensBeam\HTML\DOM\Element::setAttributeNS
+     *
+     * @covers \MensBeam\HTML\DOM\Attr::__get_value
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::__get_documentElement
+     * @covers \MensBeam\HTML\DOM\Document::createElement
+     * @covers \MensBeam\HTML\DOM\DocumentOrElement::validateAndExtract
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__construct
+     * @covers \MensBeam\HTML\DOM\Element::getAttributeNodeNS
+     * @covers \MensBeam\HTML\DOM\Element::getAttributeNS
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Node::appendChild
+     * @covers \MensBeam\HTML\DOM\Node::getInnerDocument
+     * @covers \MensBeam\HTML\DOM\Node::getInnerNode
+     * @covers \MensBeam\HTML\DOM\Node::getRootNode
+     * @covers \MensBeam\HTML\DOM\Node::postInsertionBugFixes
+     * @covers \MensBeam\HTML\DOM\Node::preInsertionBugFixes
+     * @covers \MensBeam\HTML\DOM\Node::preInsertionValidity
+     * @covers \MensBeam\HTML\DOM\NonElementParentNode::getElementById
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::getProtectedProperty
+     */
+    public function testMethod_setAttributeNS() {
+        $d = new Document();
+        $d->appendChild($d->createElement('html'));
+        $documentElement = $d->documentElement;
+
+        // Just need to test setting of a bullshit namespaced attribute and id
+        // attribute; everything else is covered already.
+        $documentElement->setAttributeNS('https://poop💩.poop💩', 'poop💩:poop💩', 'jeff');
+        $this->assertSame('jeff', $documentElement->getAttributeNS('https://poop💩.poop💩', 'poop💩'));
+        $documentElement->setAttributeNS(null, 'id', 'ook');
+        $this->assertSame($documentElement, $d->getElementById('ook'));
+    }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\Element::__get_attributes
+     *
+     * @covers \MensBeam\HTML\DOM\Attr::__get_value
+     * @covers \MensBeam\HTML\DOM\Collection::__get_length
+     * @covers \MensBeam\HTML\DOM\Collection::count
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::__get_documentElement
+     * @covers \MensBeam\HTML\DOM\Document::load
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__get_namespaceURI
+     * @covers \MensBeam\HTML\DOM\Element::getAttribute
+     * @covers \MensBeam\HTML\DOM\Element::getAttributeNode
+     * @covers \MensBeam\HTML\DOM\NamedNodeMap::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__get_ownerDocument
+     * @covers \MensBeam\HTML\DOM\Node::hasChildNodes
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__get_wrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     */
+    public function testProperty_attributes() {
+        $d = new Document('<!DOCTYPE html><html id="ook" class="eek" ack="ack" foo="foo" bar="bar" xmlns="' . Node::HTML_NAMESPACE . '"></html>', 'UTF-8');
+        $documentElement = $d->documentElement;
+        $this->assertEquals(6, $documentElement->attributes->length);
+        $this->assertSame(Node::HTML_NAMESPACE, $documentElement->getAttribute('xmlns'));
+    }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\Element::__get_id
+     * @covers \MensBeam\HTML\DOM\Element::__set_id
+     *
+     * @covers \MensBeam\HTML\DOM\Attr::__get_value
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::createElement
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__get_namespaceURI
+     * @covers \MensBeam\HTML\DOM\Element::getAttribute
+     * @covers \MensBeam\HTML\DOM\Element::getAttributeNode
+     * @covers \MensBeam\HTML\DOM\Element::setAttribute
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__get_ownerDocument
+     * @covers \MensBeam\HTML\DOM\Node::appendChild
+     * @covers \MensBeam\HTML\DOM\Node::getInnerDocument
+     * @covers \MensBeam\HTML\DOM\Node::getInnerNode
+     * @covers \MensBeam\HTML\DOM\Node::getRootNode
+     * @covers \MensBeam\HTML\DOM\Node::postInsertionBugFixes
+     * @covers \MensBeam\HTML\DOM\Node::preInsertionBugFixes
+     * @covers \MensBeam\HTML\DOM\Node::preInsertionValidity
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__get_wrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::getProtectedProperty
+     */
+    public function testProperty_id() {
+        $d = new Document();
+        $documentElement = $d->appendChild($d->createElement('html'));
+        $documentElement->id = 'ook';
+        $this->assertSame('ook', $documentElement->id);
+    }
 }
\ No newline at end of file
diff --git a/vendor-bin/phpunit/composer.lock b/vendor-bin/phpunit/composer.lock
index 73a609c..8b462ee 100644
--- a/vendor-bin/phpunit/composer.lock
+++ b/vendor-bin/phpunit/composer.lock
@@ -529,16 +529,16 @@
         },
         {
             "name": "phpunit/php-code-coverage",
-            "version": "9.2.8",
+            "version": "9.2.9",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/php-code-coverage.git",
-                "reference": "cf04e88a2e3c56fc1a65488afd493325b4c1bc3e"
+                "reference": "f301eb1453c9e7a1bc912ee8b0ea9db22c60223b"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/php-code-coverage/zipball/cf04e88a2e3c56fc1a65488afd493325b4c1bc3e",
-                "reference": "cf04e88a2e3c56fc1a65488afd493325b4c1bc3e",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-code-coverage/zipball/f301eb1453c9e7a1bc912ee8b0ea9db22c60223b",
+                "reference": "f301eb1453c9e7a1bc912ee8b0ea9db22c60223b",
                 "shasum": ""
             },
             "require": {
@@ -594,7 +594,7 @@
             ],
             "support": {
                 "issues": "https://github.com/sebastianbergmann/php-code-coverage/issues",
-                "source": "https://github.com/sebastianbergmann/php-code-coverage/tree/9.2.8"
+                "source": "https://github.com/sebastianbergmann/php-code-coverage/tree/9.2.9"
             },
             "funding": [
                 {
@@ -602,7 +602,7 @@
                     "type": "github"
                 }
             ],
-            "time": "2021-10-30T08:01:38+00:00"
+            "time": "2021-11-19T15:21:02+00:00"
         },
         {
             "name": "phpunit/php-file-iterator",