diff --git a/website/contrib/code_block/tests.py b/website/contrib/code_block/tests.py
index 66ac346..0fdf158 100644
--- a/website/contrib/code_block/tests.py
+++ b/website/contrib/code_block/tests.py
@@ -1,8 +1,10 @@
+import re
+
 from django.test import SimpleTestCase
 from django.urls import reverse
 
 from .blocks import CodeStructValue, get_language_choices
-from .utils import PYGMENTS_VERSION_SLUG
+from .utils import PYGMENTS_VERSION_SLUG, get_linguist_colours
 
 
 class PygmentsStylesTestCase(SimpleTestCase):
@@ -35,6 +37,29 @@ class CodeStructValueTestCase(SimpleTestCase):
         block = CodeStructValue(None, [("filename", ""), ("language", "Python")])
         self.assertEqual(block.header_text(), "Python")
 
+    def test_header_text_uses_language_mapping(self) -> None:
+        block = CodeStructValue(
+            None, [("filename", ""), ("language", "Python console session")]
+        )
+        self.assertEqual(block.header_text(), "Python")
+
     def test_header_text_empty_when_text(self) -> None:
         block = CodeStructValue(None, [("filename", ""), ("language", "Text only")])
         self.assertEqual(block.header_text(), "")
+
+    def test_linguist_mapping(self) -> None:
+        linguist_languages = set(get_linguist_colours().keys())
+
+        for language in CodeStructValue.LINGUIST_MAPPING.values():
+            self.assertIn(language.lower(), linguist_languages)
+
+
+class LinguistColoursTestCase(SimpleTestCase):
+    HEX_RE = re.compile(r"#[0-9A-F]", re.IGNORECASE)
+
+    def test_gets_colours(self) -> None:
+        colours = get_linguist_colours()
+
+        for colour in colours.values():
+            with self.subTest(colour):
+                self.assertRegex(colour, self.HEX_RE)