diff --git a/tests/js/htmlparser.test.js b/tests/js/htmlparser.test.js
index 20ec12a..d540abd 100644
--- a/tests/js/htmlparser.test.js
+++ b/tests/js/htmlparser.test.js
@@ -1,7 +1,7 @@
 import {expect, test} from '@jest/globals';
 import {parseEditorContent} from './src/htmlparser.mjs';
 
-test('html 1', () => {
+test('Language markers spread via several block elements.', () => {
     const html = '<p class="clo">{mlang de}</p><div>Foo bar {mlang}</div>';
     const parsed = '<p class="clo"><span contenteditable="false" class="multilang-begin mceNonEditable" '
         + 'data-mce-contenteditable="false" lang="de" xml:lang="de">{mlang de}</span>'
@@ -12,7 +12,7 @@ test('html 1', () => {
     expect(parseEditorContent(html)).toEqual(parsed);
 });
 
-test('html 2', () => {
+test('Only one closing language tag.', () => {
     const html = '<div>Foo bar {mlang}</div>';
     const parsed = '<div>Foo bar <span contenteditable="false" class="multilang-begin mceNonEditable" '
         + 'data-mce-contenteditable="false" lang="other" xml:lang="other">{mlang other}</span>'
@@ -20,7 +20,7 @@ test('html 2', () => {
     expect(parseEditorContent(html)).toEqual(parsed);
 });
 
-test('html 3', () => {
+test('Language tags in text and attribures, attributes without value.', () => {
     const html = '<p>{mlang en}This is a test{mlang}{mlang de}Das ist ein Test{mlang}.</p>\n'
         + '<p>This is a multilang link: <a\n'
         + '    href="https://google.com?lang={mlang de}de-DE{mlang}{mlang en}en-EN{mlang}" target="_blank">{mlang\n'
@@ -66,7 +66,7 @@ test('html 3', () => {
         + 'contenteditable="false" class="multilang-end mceNonEditable" data-mce-contenteditable="false">{mlang}</span></p>';
     expect(parseEditorContent(html)).toEqual(parsed);
 });
-test('html 4', () => {
+test('Already containing tiny tags for language markers.', () => {
     const html = '<p><span contenteditable="false" class="multilang-begin mceNonEditable"\n'
         + 'data-mce-contenteditable="false" lang="en" xml:lang="en">{mlang en}</span>English rules'
         + '<span contenteditable="false" class="multilang-end mceNonEditable" data-mce-contenteditable="false">{mlang}'
@@ -76,7 +76,7 @@ test('html 4', () => {
         + 'contenteditable="false" class="multilang-end mceNonEditable" data-mce-contenteditable="false">{mlang}</span></p>';
     expect(parseEditorContent(html)).toEqual(parsed);
 });
-test('html 5', () => {
+test('Html containing comments.', () => {
     const html = '<p><!-- {mlang de}</p>\n'
         + '<p>Hallo</p>\n'
         + '<p>{mlang}--></p>\n'
@@ -91,4 +91,30 @@ test('html 5', () => {
         + 'data-mce-contenteditable="false">{mlang}</span></p>\n'
         + '<p>Done</p>\n';
     expect(parseEditorContent(html)).toEqual(parsed);
+});
+test('Html containing a svg.', () => {
+    const html = '<p>Resistor: <svg xmlns="http://www.w3.org/2000/svg"\n'
+        + ' version="1.1" baseProfile="full"\n'
+        + ' width="700px" height="400px" viewBox="0 0 700 400">\n'
+        + '\n'
+        + '<!-- Connectors left and right -->\n'
+        + '<line x1="0" y1="200" x2="700" y2="200" stroke="black" stroke-width="20px"/>\n'
+        + '<!-- The rectangle -->\n'
+        + '<rect x="100" y="100" width="500" height="200" fill="white" stroke="black" stroke-width="20px"/>\n'
+        + '</svg></p>';
+    expect(parseEditorContent(html)).toEqual(html);
+});
+test('Html with tex anotations.', () => {
+    const html = '<p>The Quadratic Equation: <span class="math-tex">\\(ax^2 + bx + c = 0\\)</span></p>';
+    expect(parseEditorContent(html)).toEqual(html);
+});
+test('Html containing mathml elements.', () => {
+    const html = '<p>The Quadratic Equation: <span><math xmlns="http://www.w3.org/1998/Math/MathML">'
+	      + '  <mrow>\n'
+		    + '    <mi>a</mi> <mo>&InvisibleTimes;</mo> <msup><mi>x</mi><mn>2</mn></msup>\n'
+		    + '    <mo>+</mo><mi>b</mi><mo>&InvisibleTimes;</mo><mi>x</mi>\n'
+		    + '    <mo>+</mo><mi>c</mi>\n'
+	      + '  </mrow>\n'
+        + '</math></span></p>';
+    expect(parseEditorContent(html)).toEqual(html);
 });
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