diff --git a/.github/workflows/php.yml b/.github/workflows/php.yml
index 77b3aa5..9b0e461 100644
--- a/.github/workflows/php.yml
+++ b/.github/workflows/php.yml
@@ -30,6 +30,36 @@ jobs:
       -   name: Run PHPCSFixer
           run: php-cs-fixer fix --dry-run --diff
 
+  phpstan:
+    name: PHP Static Analysis
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        php: 
+            - '7.1'
+            - '7.2'
+            - '7.3'
+            - '7.4'
+            - '8.0'
+            - '8.1'
+            - '8.2'
+            - '8.3'
+    steps:
+        -   name: Setup PHP
+            uses: shivammathur/setup-php@v2
+            with:
+                php-version: ${{ matrix.php }}
+                extensions: xml
+
+        -   uses: actions/checkout@v2
+
+        -   name: Composer Install
+            run: composer install --ansi --prefer-dist --no-interaction --no-progress
+
+        -   name: Run phpstan
+            run: ./vendor/bin/phpstan analyse -c phpstan.neon.dist
+
   phpunit:
     name: PHPUnit
     runs-on: ubuntu-latest
diff --git a/composer.json b/composer.json
index 7637fb8..9532352 100644
--- a/composer.json
+++ b/composer.json
@@ -22,6 +22,7 @@
         "friendsofphp/php-cs-fixer": "^2.1"
     },
     "require-dev": {
-        "phpunit/phpunit": ">=7.0"
+        "phpunit/phpunit": ">=7.0",
+        "phpstan/phpstan": "^0.12.88 || ^1.0.0"
     }
 }
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
new file mode 100644
index 0000000..9521cfa
--- /dev/null
+++ b/phpstan.neon.dist
@@ -0,0 +1,12 @@
+parameters:
+  level: 7
+  bootstrapFiles:
+    - vendor/autoload.php
+  paths:
+    - src
+    - tests
+  reportUnmatchedIgnoredErrors: false
+  ignoreErrors:
+
+  ## Remove after remove ArrayObject
+  treatPhpDocTypesAsCertain: false
\ No newline at end of file
diff --git a/src/Math/Element/AbstractElement.php b/src/Math/Element/AbstractElement.php
index be7d4a8..3888de9 100644
--- a/src/Math/Element/AbstractElement.php
+++ b/src/Math/Element/AbstractElement.php
@@ -2,13 +2,18 @@
 
 namespace PhpOffice\Math\Element;
 
+use PhpOffice\Math\Math;
+
 abstract class AbstractElement
 {
     /**
-     * @var string
+     * @var Math|AbstractGroupElement|null
      */
     protected $parent;
 
+    /**
+     * @param Math|AbstractGroupElement|null $parent
+     */
     public function setParent($parent): self
     {
         $this->parent = $parent;
@@ -16,6 +21,9 @@ public function setParent($parent): self
         return $this;
     }
 
+    /**
+     * @return Math|AbstractGroupElement|null
+     */
     public function getParent()
     {
         return $this->parent;
diff --git a/src/Math/Math.php b/src/Math/Math.php
index 962d628..0eaeb2b 100644
--- a/src/Math/Math.php
+++ b/src/Math/Math.php
@@ -2,6 +2,8 @@
 
 namespace PhpOffice\Math;
 
+use PhpOffice\Math\Element\AbstractElement;
+
 class Math
 {
     /**
@@ -32,7 +34,7 @@ public function remove(Element\AbstractElement $element): self
         $this->elements = array_filter($this->elements, function ($child) use ($element) {
             return $child != $element;
         });
-        $component->setParent(null);
+        $element->setParent(null);
 
         return $this;
     }
diff --git a/src/Math/Reader/MathML.php b/src/Math/Reader/MathML.php
index eaa348f..8a370d9 100644
--- a/src/Math/Reader/MathML.php
+++ b/src/Math/Reader/MathML.php
@@ -4,6 +4,7 @@
 
 use DOMDocument;
 use DOMElement;
+use DOMNode;
 use DOMXPath;
 use Exception;
 use PhpOffice\Math\Element;
@@ -41,10 +42,13 @@ public function read(string $content): ?Math
         return $this->math;
     }
 
-    protected function parseNode(?DOMElement $nodeRowElement, $parent): void
+    /**
+     * @param Math|Element\AbstractGroupElement $parent
+     */
+    protected function parseNode(?DOMNode $nodeRowElement, $parent): void
     {
         $this->xpath = new DOMXpath($this->dom);
-        foreach ($this->xpath->query('*', $nodeRowElement) as $nodeElement) {
+        foreach ($this->xpath->query('*', $nodeRowElement) ?: [] as $nodeElement) {
             $element = $this->getElement($nodeElement);
             $parent->add($element);
 
@@ -54,14 +58,14 @@ protected function parseNode(?DOMElement $nodeRowElement, $parent): void
         }
     }
 
-    protected function getElement(DOMElement $nodeElement): Element\AbstractElement
+    protected function getElement(DOMNode $nodeElement): Element\AbstractElement
     {
         $nodeValue = trim($nodeElement->nodeValue);
         switch ($nodeElement->nodeName) {
             case 'mfrac':
                 $element = new Element\Fraction();
                 $nodeList = $this->xpath->query('*', $nodeElement);
-                if ($nodeList->length == 2) {
+                if ($nodeList && $nodeList->length == 2) {
                     $element
                         ->setNumerator($this->getElement($nodeList->item(0)))
                         ->setDenominator($this->getElement($nodeList->item(1)));
@@ -71,13 +75,15 @@ protected function getElement(DOMElement $nodeElement): Element\AbstractElement
             case 'mi':
                 return new Element\Identifier($nodeValue);
             case 'mn':
-                return new Element\Numeric($nodeValue);
+                return new Element\Numeric(floatval($nodeValue));
             case 'mo':
                 if (empty($nodeValue)) {
                     $nodeList = $this->xpath->query('*', $nodeElement);
                     if (
-                        $nodeList->length == 1
+                        $nodeList
+                        && $nodeList->length == 1
                         && $nodeList->item(0)->nodeName == 'mchar'
+                        && $nodeList->item(0) instanceof DOMElement
                         && $nodeList->item(0)->hasAttribute('name')
                     ) {
                         $nodeValue = $nodeList->item(0)->getAttribute('name');
@@ -90,7 +96,7 @@ protected function getElement(DOMElement $nodeElement): Element\AbstractElement
             case 'msup':
                 $element = new Element\Superscript();
                 $nodeList = $this->xpath->query('*', $nodeElement);
-                if ($nodeList->length == 2) {
+                if ($nodeList && $nodeList->length == 2) {
                     $element
                         ->setBase($this->getElement($nodeList->item(0)))
                         ->setSuperscript($this->getElement($nodeList->item(1)));
diff --git a/src/Math/Reader/OfficeMathML.php b/src/Math/Reader/OfficeMathML.php
index a6a7ee6..0f46874 100644
--- a/src/Math/Reader/OfficeMathML.php
+++ b/src/Math/Reader/OfficeMathML.php
@@ -3,7 +3,7 @@
 namespace PhpOffice\Math\Reader;
 
 use DOMDocument;
-use DOMElement;
+use DOMNode;
 use DOMXPath;
 use Exception;
 use PhpOffice\Math\Element;
@@ -11,12 +11,12 @@
 
 class OfficeMathML implements ReaderInterface
 {
+    /** @var DOMDocument */
+    protected $dom;
+
     /** @var Math */
     protected $math;
 
-    /** @var XMLReader */
-    protected $xmlReader;
-
     /** @var DOMXpath */
     protected $xpath;
 
@@ -46,11 +46,13 @@ public function read(string $content): ?Math
     /**
      * @see https://devblogs.microsoft.com/math-in-office/officemath/
      * @see https://learn.microsoft.com/fr-fr/archive/blogs/murrays/mathml-and-ecma-math-omml
+     *
+     * @param Math|Element\AbstractGroupElement $parent
      */
-    protected function parseNode(?DOMElement $nodeRowElement, $parent): void
+    protected function parseNode(?DOMNode $nodeRowElement, $parent): void
     {
         $this->xpath = new DOMXpath($this->dom);
-        foreach ($this->xpath->query('*', $nodeRowElement) as $nodeElement) {
+        foreach ($this->xpath->query('*', $nodeRowElement) ?: [] as $nodeElement) {
             $element = $this->getElement($nodeElement);
             $parent->add($element);
 
@@ -60,27 +62,27 @@ protected function parseNode(?DOMElement $nodeRowElement, $parent): void
         }
     }
 
-    protected function getElement(DOMElement $nodeElement): Element\AbstractElement
+    protected function getElement(DOMNode $nodeElement): Element\AbstractElement
     {
         switch ($nodeElement->nodeName) {
             case 'm:f':
                 $element = new Element\Fraction();
                 // Numerator
                 $nodeNumerator = $this->xpath->query('m:num/m:r/m:t', $nodeElement);
-                if ($nodeNumerator->length == 1) {
+                if ($nodeNumerator && $nodeNumerator->length == 1) {
                     $value = $nodeNumerator->item(0)->nodeValue;
                     if (is_numeric($value)) {
-                        $element->setNumerator(new Element\Numeric($value));
+                        $element->setNumerator(new Element\Numeric(floatval($value)));
                     } else {
                         $element->setNumerator(new Element\Identifier($value));
                     }
                 }
                 // Denominator
                 $nodeDenominator = $this->xpath->query('m:den/m:r/m:t', $nodeElement);
-                if ($nodeDenominator->length == 1) {
+                if ($nodeDenominator && $nodeDenominator->length == 1) {
                     $value = $nodeDenominator->item(0)->nodeValue;
                     if (is_numeric($value)) {
-                        $element->setDenominator(new Element\Numeric($value));
+                        $element->setDenominator(new Element\Numeric(floatval($value)));
                     } else {
                         $element->setDenominator(new Element\Identifier($value));
                     }
@@ -89,18 +91,19 @@ protected function getElement(DOMElement $nodeElement): Element\AbstractElement
                 return $element;
             case 'm:r':
                 $nodeText = $this->xpath->query('m:t', $nodeElement);
-                if ($nodeText->length == 1) {
+                if ($nodeText && $nodeText->length == 1) {
                     $value = trim($nodeText->item(0)->nodeValue);
                     if (in_array($value, $this->operators)) {
                         return new Element\Operator($value);
                     }
                     if (is_numeric($value)) {
-                        return new Element\Numeric($value);
+                        return new Element\Numeric(floatval($value));
                     }
 
                     return new Element\Identifier($value);
                 }
-                break;
+
+                return new Element\Identifier('');
             case 'm:oMath':
                 return new Element\Row();
             default:
diff --git a/src/Math/Writer/MathML.php b/src/Math/Writer/MathML.php
index 374131b..76d1a64 100644
--- a/src/Math/Writer/MathML.php
+++ b/src/Math/Writer/MathML.php
@@ -69,10 +69,21 @@ protected function writeElementItem(Element\AbstractElement $element): void
             return;
         }
 
-        // Element\AbstractElement
-        $this->output->startElement($this->getElementTagName($element));
-        $this->output->text((string) $element->getValue());
-        $this->output->endElement();
+        if ($element instanceof Element\Identifier
+          || $element instanceof Element\Numeric
+          || $element instanceof Element\Operator) {
+            $this->output->startElement($this->getElementTagName($element));
+            $this->output->text((string) $element->getValue());
+            $this->output->endElement();
+
+            return;
+        }
+
+        throw new Exception(sprintf(
+            '%s : The class `%s` is not implemented',
+            __METHOD__,
+            get_class($element)
+        ));
     }
 
     protected function getElementTagName(Element\AbstractElement $element): string
diff --git a/src/Math/Writer/OfficeMathML.php b/src/Math/Writer/OfficeMathML.php
index 3d986d4..11153ab 100644
--- a/src/Math/Writer/OfficeMathML.php
+++ b/src/Math/Writer/OfficeMathML.php
@@ -62,12 +62,23 @@ protected function writeElementItem(Element\AbstractElement $element): void
             return;
         }
 
-        // Element\AbstractElement
-        $this->output->startElement('m:r');
-        $this->output->startElement('m:t');
-        $this->output->text((string) $element->getValue());
-        $this->output->endElement();
-        $this->output->endElement();
+        if ($element instanceof Element\Identifier
+          || $element instanceof Element\Numeric
+          || $element instanceof Element\Operator) {
+            $this->output->startElement('m:r');
+            $this->output->startElement('m:t');
+            $this->output->text((string) $element->getValue());
+            $this->output->endElement();
+            $this->output->endElement();
+
+            return;
+        }
+
+        throw new Exception(sprintf(
+            '%s : The class `%s` is not implemented',
+            __METHOD__,
+            get_class($element)
+        ));
     }
 
     protected function getElementTagName(Element\AbstractElement $element): string
diff --git a/tests/Math/Reader/MathMLTest.php b/tests/Math/Reader/MathMLTest.php
index f0dc326..617a746 100644
--- a/tests/Math/Reader/MathMLTest.php
+++ b/tests/Math/Reader/MathMLTest.php
@@ -34,39 +34,64 @@ public function testReadBasic(): void
         $this->assertCount(1, $elements);
         $this->assertInstanceOf(Element\Row::class, $elements[0]);
 
+        /** @var Element\Row $element */
         $element = $elements[0];
         $subElements = $element->getElements();
         $this->assertCount(9, $subElements);
 
-        $this->assertInstanceOf(Element\Identifier::class, $subElements[0]);
-        $this->assertEquals('a', $subElements[0]->getValue());
+        /** @var Element\Identifier $subElement */
+        $subElement = $subElements[0];
+        $this->assertInstanceOf(Element\Identifier::class, $subElement);
+        $this->assertEquals('a', $subElement->getValue());
 
-        $this->assertInstanceOf(Element\Operator::class, $subElements[1]);
-        $this->assertEquals('InvisibleTimes', $subElements[1]->getValue());
+        /** @var Element\Identifier $subElement */
+        $subElement = $subElements[1];
+        $this->assertInstanceOf(Element\Operator::class, $subElement);
+        $this->assertEquals('InvisibleTimes', $subElement->getValue());
 
+        /** @var Element\Superscript $subElement */
+        $subElement = $subElements[2];
         $this->assertInstanceOf(Element\Superscript::class, $subElements[2]);
-        $this->assertInstanceOf(Element\Identifier::class, $subElements[2]->getBase());
-        $this->assertEquals('x', $subElements[2]->getBase()->getValue());
-        $this->assertInstanceOf(Element\Numeric::class, $subElements[2]->getSuperscript());
-        $this->assertEquals(2, $subElements[2]->getSuperscript()->getValue());
 
-        $this->assertInstanceOf(Element\Operator::class, $subElements[3]);
-        $this->assertEquals('+', $subElements[3]->getValue());
-
-        $this->assertInstanceOf(Element\Identifier::class, $subElements[4]);
-        $this->assertEquals('b', $subElements[4]->getValue());
-
-        $this->assertInstanceOf(Element\Operator::class, $subElements[5]);
-        $this->assertEquals('InvisibleTimes', $subElements[5]->getValue());
-
-        $this->assertInstanceOf(Element\Identifier::class, $subElements[6]);
-        $this->assertEquals('x', $subElements[6]->getValue());
-
-        $this->assertInstanceOf(Element\Operator::class, $subElements[7]);
-        $this->assertEquals('+', $subElements[7]->getValue());
-
-        $this->assertInstanceOf(Element\Identifier::class, $subElements[8]);
-        $this->assertEquals('c', $subElements[8]->getValue());
+        /** @var Element\Identifier $base */
+        $base = $subElement->getBase();
+        $this->assertInstanceOf(Element\Identifier::class, $base);
+        $this->assertEquals('x', $base->getValue());
+
+        /** @var Element\Numeric $superscript */
+        $superscript = $subElement->getSuperscript();
+        $this->assertInstanceOf(Element\Numeric::class, $superscript);
+        $this->assertEquals(2, $superscript->getValue());
+
+        /** @var Element\Operator $subElement */
+        $subElement = $subElements[3];
+        $this->assertInstanceOf(Element\Operator::class, $subElement);
+        $this->assertEquals('+', $subElement->getValue());
+
+        /** @var Element\Identifier $subElement */
+        $subElement = $subElements[4];
+        $this->assertInstanceOf(Element\Identifier::class, $subElement);
+        $this->assertEquals('b', $subElement->getValue());
+
+        /** @var Element\Operator $subElement */
+        $subElement = $subElements[5];
+        $this->assertInstanceOf(Element\Operator::class, $subElement);
+        $this->assertEquals('InvisibleTimes', $subElement->getValue());
+
+        /** @var Element\Identifier $subElement */
+        $subElement = $subElements[6];
+        $this->assertInstanceOf(Element\Identifier::class, $subElement);
+        $this->assertEquals('x', $subElement->getValue());
+
+        /** @var Element\Operator $subElement */
+        $subElement = $subElements[7];
+        $this->assertInstanceOf(Element\Operator::class, $subElement);
+        $this->assertEquals('+', $subElement->getValue());
+
+        /** @var Element\Identifier $subElement */
+        $subElement = $subElements[8];
+        $this->assertInstanceOf(Element\Identifier::class, $subElement);
+        $this->assertEquals('c', $subElement->getValue());
     }
 
     /**
@@ -97,20 +122,33 @@ public function testReadFraction(): void
         $this->assertCount(1, $elements);
         $this->assertInstanceOf(Element\Fraction::class, $elements[0]);
 
+        /** @var Element\Fraction $element */
         $element = $elements[0];
 
         $this->assertInstanceOf(Element\Fraction::class, $element->getNumerator());
+        /** @var Element\Fraction $subElement */
         $subElement = $element->getNumerator();
-        $this->assertInstanceOf(Element\Identifier::class, $subElement->getNumerator());
-        $this->assertEquals('a', $subElement->getNumerator()->getValue());
-        $this->assertInstanceOf(Element\Identifier::class, $subElement->getDenominator());
-        $this->assertEquals('b', $subElement->getDenominator()->getValue());
+
+        /** @var Element\Identifier $numerator */
+        $numerator = $subElement->getNumerator();
+        $this->assertInstanceOf(Element\Identifier::class, $numerator);
+        $this->assertEquals('a', $numerator->getValue());
+        /** @var Element\Identifier $denominator */
+        $denominator = $subElement->getDenominator();
+        $this->assertInstanceOf(Element\Identifier::class, $denominator);
+        $this->assertEquals('b', $denominator->getValue());
 
         $this->assertInstanceOf(Element\Fraction::class, $element->getDenominator());
+        /** @var Element\Fraction $subElement */
         $subElement = $element->getDenominator();
-        $this->assertInstanceOf(Element\Identifier::class, $subElement->getNumerator());
-        $this->assertEquals('c', $subElement->getNumerator()->getValue());
-        $this->assertInstanceOf(Element\Identifier::class, $subElement->getDenominator());
-        $this->assertEquals('d', $subElement->getDenominator()->getValue());
+
+        /** @var Element\Identifier $numerator */
+        $numerator = $subElement->getNumerator();
+        $this->assertInstanceOf(Element\Identifier::class, $numerator);
+        $this->assertEquals('c', $numerator->getValue());
+        /** @var Element\Identifier $denominator */
+        $denominator = $subElement->getDenominator();
+        $this->assertInstanceOf(Element\Identifier::class, $denominator);
+        $this->assertEquals('d', $denominator->getValue());
     }
 }
diff --git a/tests/Math/Reader/OfficeMathMLTest.php b/tests/Math/Reader/OfficeMathMLTest.php
index 0d17dd1..c88bf60 100644
--- a/tests/Math/Reader/OfficeMathMLTest.php
+++ b/tests/Math/Reader/OfficeMathMLTest.php
@@ -33,15 +33,24 @@ public function testRead(): void
         $this->assertCount(1, $elements);
         $this->assertInstanceOf(Element\Row::class, $elements[0]);
 
-        $subElements = $elements[0]->getElements();
+        /** @var Element\Row $element */
+        $element = $elements[0];
+        $subElements = $element->getElements();
         $this->assertCount(1, $subElements);
         $this->assertInstanceOf(Element\Fraction::class, $subElements[0]);
 
-        $this->assertInstanceOf(Element\Identifier::class, $subElements[0]->getNumerator());
-        $this->assertEquals('π', $subElements[0]->getNumerator()->getValue());
+        /** @var Element\Fraction $subElement */
+        $subElement = $subElements[0];
 
-        $this->assertInstanceOf(Element\Numeric::class, $subElements[0]->getDenominator());
-        $this->assertEquals(2, $subElements[0]->getDenominator()->getValue());
+        /** @var Element\Identifier $numerator */
+        $numerator = $subElement->getNumerator();
+        $this->assertInstanceOf(Element\Identifier::class, $numerator);
+        $this->assertEquals('π', $numerator->getValue());
+
+        /** @var Element\Numeric $denominator */
+        $denominator = $subElement->getDenominator();
+        $this->assertInstanceOf(Element\Numeric::class, $denominator);
+        $this->assertEquals(2, $denominator->getValue());
     }
 
     /**
@@ -89,22 +98,36 @@ public function testReadWithWTag(): void
         $elements = $math->getElements();
         $this->assertCount(5, $elements);
 
-        $this->assertInstanceOf(Element\Fraction::class, $elements[0]);
-        $this->assertInstanceOf(Element\Identifier::class, $elements[0]->getNumerator());
-        $this->assertEquals('π', $elements[0]->getNumerator()->getValue());
-        $this->assertInstanceOf(Element\Numeric::class, $elements[0]->getDenominator());
-        $this->assertEquals(2, $elements[0]->getDenominator()->getValue());
-
-        $this->assertInstanceOf(Element\Operator::class, $elements[1]);
-        $this->assertEquals('+', $elements[1]->getValue());
-
-        $this->assertInstanceOf(Element\Identifier::class, $elements[2]);
-        $this->assertEquals('a', $elements[2]->getValue());
-
-        $this->assertInstanceOf(Element\Operator::class, $elements[3]);
-        $this->assertEquals('∗', $elements[3]->getValue());
-
-        $this->assertInstanceOf(Element\Numeric::class, $elements[4]);
-        $this->assertEquals(2, $elements[4]->getValue());
+        /** @var Element\Fraction $element */
+        $element = $elements[0];
+        $this->assertInstanceOf(Element\Fraction::class, $element);
+        /** @var Element\Identifier $numerator */
+        $numerator = $element->getNumerator();
+        $this->assertInstanceOf(Element\Identifier::class, $numerator);
+        $this->assertEquals('π', $numerator->getValue());
+        /** @var Element\Numeric $denominator */
+        $denominator = $element->getDenominator();
+        $this->assertInstanceOf(Element\Numeric::class, $denominator);
+        $this->assertEquals(2, $denominator->getValue());
+
+        /** @var Element\Operator $element */
+        $element = $elements[1];
+        $this->assertInstanceOf(Element\Operator::class, $element);
+        $this->assertEquals('+', $element->getValue());
+
+        /** @var Element\Identifier $element */
+        $element = $elements[2];
+        $this->assertInstanceOf(Element\Identifier::class, $element);
+        $this->assertEquals('a', $element->getValue());
+
+        /** @var Element\Operator $element */
+        $element = $elements[3];
+        $this->assertInstanceOf(Element\Operator::class, $element);
+        $this->assertEquals('∗', $element->getValue());
+
+        /** @var Element\Numeric $element */
+        $element = $elements[4];
+        $this->assertInstanceOf(Element\Numeric::class, $element);
+        $this->assertEquals(2, $element->getValue());
     }
 }
diff --git a/tests/Math/Writer/WriterTestCase.php b/tests/Math/Writer/WriterTestCase.php
index 778fe26..482019f 100644
--- a/tests/Math/Writer/WriterTestCase.php
+++ b/tests/Math/Writer/WriterTestCase.php
@@ -5,6 +5,7 @@
 namespace Tests\PhpOffice\Math\Writer;
 
 use DOMDocument;
+use LibXMLError;
 use PHPUnit\Framework\TestCase;
 
 class WriterTestCase extends TestCase
@@ -15,21 +16,27 @@ public function assertIsSchemaMathMLValid(string $content): void
         $dom->loadXML($content);
         $xmlSource = $dom->saveXML();
 
-        $dom->loadXML($xmlSource);
-        $dom->schemaValidate(dirname(__DIR__, 2) . '/resources/schema/mathml3/mathml3.xsd');
+        if (is_string($xmlSource)) {
+            $dom->loadXML($xmlSource);
+            $dom->schemaValidate(dirname(__DIR__, 2) . '/resources/schema/mathml3/mathml3.xsd');
 
-        $error = libxml_get_last_error();
-        if ($error instanceof LibXMLError) {
-            $this->failXmlError($error, $fileName, $xmlSource);
-        } else {
-            $this->assertTrue(true);
+            $error = libxml_get_last_error();
+            if ($error instanceof LibXMLError) {
+                $this->failXmlError($error, $xmlSource);
+            } else {
+                $this->assertTrue(true);
+            }
+
+            return;
         }
+
+        $this->fail(sprintf('The XML is not valid : %s', $content));
     }
 
     /**
      * @param array<string, string> $params
      */
-    protected function failXmlError(LibXMLError $error, string $fileName, string $source, array $params = []): void
+    protected function failXmlError(LibXMLError $error, string $source, array $params = []): void
     {
         switch ($error->level) {
             case LIBXML_ERR_WARNING:
@@ -65,9 +72,8 @@ protected function failXmlError(LibXMLError $error, string $fileName, string $so
             }
         }
         $this->fail(sprintf(
-            "Validation %s :\n - File : %s\n - Line : %s\n - Message : %s - Lines :\n%s%s",
+            "Validation %s :\n - - Line : %s\n - Message : %s - Lines :\n%s%s",
             $errorType,
-            $fileName,
             $error->line,
             $error->message,
             implode(PHP_EOL, $lines),