diff --git a/backend/tests/test_special_value_file_format.py b/backend/tests/test_special_value_file_format.py
new file mode 100644
index 0000000..749202b
--- /dev/null
+++ b/backend/tests/test_special_value_file_format.py
@@ -0,0 +1,27 @@
+"""
+TC_004 - Special value test for uploading a valid and invalid file to a workout.
+"""
+def test_file_upload_special_value(self):
+  # Creates a PDF-file
+  pdf_file = SimpleUploadedFile("pdf_file.pdf") 
+  # Creates a DOCX-file
+  docx_file = SimpleUploadedFile("docx_file.docx") 
+  # Creates AthleteFile object with the files
+  athlete_pdf_file = AthleteFile(athlete=self.user, owner=self.user, file=pdf_file)
+  athlete_docx_file = AthleteFile(athlete=self.user, owner=self.user, file=docx_file)
+
+  try:
+    # Runs validation check for PDF-file
+    athlete_pdf_file.full_clean()
+  except ValidationError as e:
+    # Fails if any validation errors are raised
+    self.fail(f"ValidationError raised: {e}")
+
+  try:
+    # Runs validation check for DOCX-file
+    athlete_pdf_file.full_clean()
+    # Fails if no validation errors are raised
+    self.fail("ValidationError not raised for file of format DOCX.")
+  except ValidationError as e:
+    # Passes if validation error is raised.
+    self.assertIn('file', e.message_dict)