diff --git a/shiftregister/fallback/tests.py b/shiftregister/fallback/tests.py
index 7ce503c..c242819 100644
--- a/shiftregister/fallback/tests.py
+++ b/shiftregister/fallback/tests.py
@@ -1,3 +1,171 @@
-from django.test import TestCase
+import uuid
+from datetime import timedelta
 
-# Create your tests here.
+from django.test import Client, TestCase
+from django.urls import reverse
+from django.utils import timezone
+
+from shiftregister.fallback.models import FallbackAssignment, TeamMember
+from shiftregister.importer.models import Calendar, Event, Room
+
+
+class ShiftTradeTests(TestCase):
+    def setUp(self):
+        # Create test data
+        self.room = Room.objects.create(name="Test Room", required_helpers=2)
+
+        self.event = Event.objects.create(
+            uuid=uuid.uuid4(),
+            calendar=Calendar.objects.create(url="https://example.com/calendar"),
+            start_at=timezone.now(),
+            duration=timedelta(hours=2),
+            room=self.room,
+            deleted=False,
+        )
+
+        self.team_member1 = TeamMember.objects.create(name="Team Member 1", pin=1111)
+
+        self.team_member2 = TeamMember.objects.create(name="Team Member 2", pin=2222)
+
+        self.team_member3 = TeamMember.objects.create(name="Team Member 3", pin=3333)
+
+        self.assignment = FallbackAssignment.objects.create(
+            shift=self.event, team_member=self.team_member1, traded_to=self.team_member3
+        )
+
+        self.client = Client()
+
+    def test_invalid_pin_keeps_assignment_unchanged(self):
+        """Test that wrong PIN prevents any changes to the assignment"""
+        response = self.client.post(
+            reverse(
+                "my_fallback_shifts",
+                kwargs={"team_member_id": self.team_member2.url_id()},
+            ),
+            {"take_shift": "true", "assignment_id": self.assignment.id, "pin": "9999"},
+        )
+
+        self.assignment.refresh_from_db()
+        self.assertEqual(self.assignment.team_member, self.team_member1)
+        self.assertEqual(self.assignment.traded_to, self.team_member3)
+
+    def test_take_shift_updates_traded_to(self):
+        """Test that taking a shift properly updates the traded_to field"""
+        response = self.client.post(
+            reverse(
+                "my_fallback_shifts",
+                kwargs={"team_member_id": self.team_member2.url_id()},
+            ),
+            {
+                "take_shift": "true",
+                "assignment_id": self.assignment.id,
+                "pin": self.team_member2.pin,
+            },
+            follow=True,
+        )
+
+        # Assignment should now be traded to team_member2
+        self.assignment.refresh_from_db()
+        self.assertEqual(self.assignment.traded_to, self.team_member2)
+        self.assertEqual(
+            self.assignment.team_member, self.team_member1
+        )  # Original owner unchanged
+
+    def test_return_shift_clears_traded_to(self):
+        """Test that returning a shift clears the traded_to field"""
+
+        # Then return it
+        response = self.client.post(
+            reverse(
+                "my_fallback_shifts",
+                kwargs={"team_member_id": self.team_member3.url_id()},
+            ),
+            {
+                "take_shift": "true",
+                "assignment_id": self.assignment.id,
+                "pin": self.team_member3.pin,
+            },
+            follow=True,
+        )
+
+        # Assignment should be returned (traded_to cleared)
+        self.assignment.refresh_from_db()
+        self.assertIsNone(self.assignment.traded_to)
+        self.assertEqual(
+            self.assignment.team_member, self.team_member1
+        )  # Original owner unchanged
+
+    def test_reclaim_shift_clears_traded_to(self):
+        """Test that original owner can reclaim their shift"""
+
+        # Original owner reclaims it
+        response = self.client.post(
+            reverse(
+                "my_fallback_shifts",
+                kwargs={"team_member_id": self.team_member1.url_id()},
+            ),
+            {
+                "take_shift": "true",
+                "assignment_id": self.assignment.id,
+                "pin": self.team_member1.pin,
+            },
+            follow=True,
+        )
+
+        # Assignment should be reclaimed (traded_to cleared)
+        self.assignment.refresh_from_db()
+        self.assertIsNone(self.assignment.traded_to)
+        self.assertEqual(self.assignment.team_member, self.team_member1)
+
+    def test_take_shift_from_other_trader(self):
+        """Test that a member can take over a shift that was already traded to someone else"""
+        # Verify initial state
+        self.assertEqual(self.assignment.team_member, self.team_member1)
+        self.assertEqual(self.assignment.traded_to, self.team_member3)
+
+        # team_member2 takes the shift from team_member3
+        response = self.client.post(
+            reverse(
+                "my_fallback_shifts",
+                kwargs={"team_member_id": self.team_member2.url_id()},
+            ),
+            {
+                "take_shift": "true",
+                "assignment_id": self.assignment.id,
+                "pin": self.team_member2.pin,
+            },
+            follow=True,
+        )
+
+        # Assignment should now be traded to team_member2
+        self.assignment.refresh_from_db()
+        self.assertEqual(
+            self.assignment.team_member, self.team_member1
+        )  # Original owner unchanged
+        self.assertEqual(self.assignment.traded_to, self.team_member2)  # New trader
+
+    def test_form_validation_prevents_changes(self):
+        """Test that invalid form data doesn't modify any assignments"""
+        initial_count = FallbackAssignment.objects.count()
+        initial_state = FallbackAssignment.objects.values_list(
+            "id", "team_member_id", "traded_to_id"
+        )
+
+        response = self.client.post(
+            reverse(
+                "my_fallback_shifts",
+                kwargs={"team_member_id": self.team_member1.url_id()},
+            ),
+            {
+                "take_shift": "true",
+                "assignment_id": "not_a_number",
+                "pin": "also_not_a_number",
+            },
+        )
+
+        # No assignments should be created or modified
+        self.assertEqual(FallbackAssignment.objects.count(), initial_count)
+        current_state = FallbackAssignment.objects.values_list(
+            "id", "team_member_id", "traded_to_id"
+        )
+        self.assertEqual(list(initial_state), list(current_state))
diff --git a/shiftregister/settings.py b/shiftregister/settings.py
index 51841a0..34e8083 100644
--- a/shiftregister/settings.py
+++ b/shiftregister/settings.py
@@ -10,6 +10,7 @@ For the full list of settings and their values, see
 https://docs.djangoproject.com/en/4.0/ref/settings/
 """
 
+import sys
 from pathlib import Path
 
 import environ
@@ -31,6 +32,9 @@ environ.Env.read_env(BASE_DIR / ".env")
 # SECURITY WARNING: don't run with debug turned on in production!
 DEBUG = env("ENVIRONMENT") == "development"
 
+# Check if we're running tests
+TESTING = "test" in sys.argv
+
 # SECURITY WARNING: keep the secret key used in production secret!
 SECRET_KEY = env(
     "SECRET_KEY",
@@ -61,7 +65,7 @@ THIRDPARTY_APPS = [
     "phonenumber_field",
 ]
 
-if DEBUG:
+if DEBUG and not TESTING:
     THIRDPARTY_APPS += ["debug_toolbar"]
 
 LOCAL_APPS = [
@@ -90,7 +94,7 @@ MIDDLEWARE = [
     "shiftregister.app.middleware.check_helper",
 ]
 
-if DEBUG:
+if DEBUG and not TESTING:
     MIDDLEWARE.insert(0, "debug_toolbar.middleware.DebugToolbarMiddleware")
 
 ROOT_URLCONF = "shiftregister.urls"