diff --git a/backend/tests/test_boundary_file_size.py b/backend/tests/test_boundary_file_size.py
new file mode 100644
index 0000000..c8feffe
--- /dev/null
+++ b/backend/tests/test_boundary_file_size.py
@@ -0,0 +1,33 @@
+"""
+TC_002 - Boundary test for file size
+"""
+from django.test import TestCase
+
+def test_file_size_boundary(self):
+  # Create file with minimum valid size (1 byte)
+  min_file = SimpleUploadedFile("min_file.txt", b"x" * 1)
+
+  # Create file with minimum valid size (2 bytes)
+  min_plus_file = SimpleUploadedFile("min_plus_file.txt", b"x" * 2)
+
+  # Create file with maximum valid size (5MB - 1 byte)
+  max_minus_file = SimpleUploadedFile("max_minus_file.txt", b"x" * (max_size - 1))
+
+  # Create file with maximum valid size (5MB)
+  max_file = SimpleUploadedFile("max_file.txt", b"x" * max_size)
+
+  # Create AthleteFile objects with both files
+  athlete_min_file = AthleteFile(athlete=self.user, owner=self.user, file=min_file)
+  athlete_min_plus_file = AthleteFile(athlete=self.user, owner=self.user, file=min_plus_file)
+  athlete_max_minus_file = AthleteFile(athlete=self.user, owner=self.user, file=max_minus_file)
+  athlete_max_file = AthleteFile(athlete=self.user, owner=self.user, file=max_file)
+
+  try:
+    # Runs validation checks
+    athlete_min_file.full_clean()
+    athlete_min_plus_file.full_clean()
+    athlete_max_minus_file.full_clean()
+    athlete_max_file.full_clean()
+  except ValidationError as e:
+    # Fails if any validation errors are raised
+    self.fail(f"ValidationError raised: {e}")
diff --git a/backend/tests/test_equivalence_class_exercise.py b/backend/tests/test_equivalence_class_exercise.py
new file mode 100644
index 0000000..5a3004a
--- /dev/null
+++ b/backend/tests/test_equivalence_class_exercise.py
@@ -0,0 +1,48 @@
+"""
+TC_001 - Equivalence class test for the limit of sets in an exercise
+"""
+from django.test import TestCase
+from workouts.models import ExerciseInstance
+
+# Test an exercise instance with the lowest equivalence class
+def test_create_below_exercise_instance(self):
+  response = self.client.post("api/exercise-instances/",
+    "workout": "Full body toning",
+    "exercise": "Squats",
+    "sets": -10, # A negative number of sets is expected to raise an error
+    "number": 5
+  }, format="json")
+
+  print(f"Error response data: {response.data}")
+  print(f"Error response status code: {response.status_code}")
+
+  assert response.status_code == 400
+    
+# Test an exercise instance with the mid and valid equivalence class
+def test_create_valid_exercise_instance(self):
+  response = self.client.post("/api/exercise-instances/", {
+    "workout": "Full body toning",
+    "exercise": "Squats",
+    "sets": 50, # A number of sets between 0 and 100 is expected to be valid
+    "number": 5
+  }, format="json")
+    
+  print(f"Response data: {response.data}")
+  print(f"Response status code: {response.status_code}")
+
+  assert response.status_code == 201
+  assert ExerciseInstance.objects.count() == 1
+
+# Test an exercise instance with the highest equivalence class
+def test_create_below_exercise_instance(self):
+  response = self.client.post("api/exercise-instances/", {
+    "workout": "Full body toning",
+    "exercise": "Squats",
+    "sets": 110, # A number of sets above 100 is expected to raise an error
+    "number": 5
+  }, format="json")
+
+  print(f"Error response data: {response.data}")
+  print(f"Error response status code: {response.status_code}")
+
+  assert response.status_code == 400
diff --git a/backend/tests/test_robust_boundary_file_size.py b/backend/tests/test_robust_boundary_file_size.py
new file mode 100644
index 0000000..325b4d1
--- /dev/null
+++ b/backend/tests/test_robust_boundary_file_size.py
@@ -0,0 +1,19 @@
+"""
+TC_003 - Robust boundary test for file size above maximum size
+"""
+from django.test import TestCase
+
+def test_file_size_robust_boundary(self):
+  # Creates a file with invalid size
+  invalid_above_file = SimpleUploadedFile("test_above_max.txt", b"x" * (max_size + 1)) 
+  # Creates AthleteFile object with the invalid file
+  athlete_above_file = AthleteFile(athlete=self.user, owner=self.user, file=invalid_above_file)
+
+  try:
+    # Runs a validation check
+    athlete_above_file.full_clean()
+    # Fails if no validation errors are raised
+    self.fail("ValidationError not raised for file above maximum size.")
+  except ValidationError as e:
+    # Passes if validation error is raised.
+    self.assertIn('file', e.message_dict)
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..9ecf204
--- /dev/null
+++ b/backend/tests/test_special_value_file_format.py
@@ -0,0 +1,29 @@
+"""
+TC_004 - Special value test for uploading a valid and invalid file to a workout.
+"""
+from django.test import TestCase
+
+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)
diff --git a/backend/tests/test_special_value_workout.py b/backend/tests/test_special_value_workout.py
new file mode 100644
index 0000000..3c58a1c
--- /dev/null
+++ b/backend/tests/test_special_value_workout.py
@@ -0,0 +1,35 @@
+"""
+TC_005 - Special value test for the limit of sets in an exercise instance
+"""
+from django.test import TestCase
+
+def test_create_valid_workout(self):
+  response = self.client.post("/api/workouts/", {
+    "name": "Full body toning",
+    "date": now().isoformat(),
+    "notes": "Workout for women",
+    "visibility": "PU",
+    "owner": self.user.id,
+    "exercise_instances": []
+  }, format="json")
+
+  print(f"Response data: {response.data}")
+  print(f"Response status code: {response.status_code}")
+
+  assert response.status_code == 201
+  assert Workout.objects.count() == 1
+ 
+def test_create_invalid_workout(self):
+  response = self.client.post("/api/workouts/", {
+    "name": "Full body toning",
+    "date": "today", # text instead of a date format
+    "notes": "Workout for women",
+    "visibility": "XO", # non-existent visibility
+    "owner": self.user.id,
+    "exercise_instances": []
+    }, format="json")
+    
+  print(f"Error response data: {response.data}")
+  print(f"Error response status code: {response.status_code}")
+
+  assert response.status_code == 400