devices need to be unique per customer

devices/models/device.py

@@ -78,6 +78,7 @@ class Device(models.Model):
 
     class Meta:
         ordering = ['name']
+        unique_together = ("name", "customer")
 
     def __str__(self):
         return self.name

devices/tests/test_device_form.py

@@ -41,3 +41,15 @@ def test_device_update_form(create_admin_user):
             "customer": fixture['customer'].id}
     form = forms.DeviceUpdateForm(data=data)
     assert form.is_valid() is True, ("Should be valid with the given data.")
+
+
+def test_device_create_form_duplicate_device(create_admin_user):
+    fixture = create_admin_user()
+    user = mixer.blend("auth.User", customer=fixture['customer'])
+    mixer.blend("devices.Device", name="pharma-device1",
+                customer=fixture['customer'])
+    data = {"name": "pharma-device1",
+            "customer": fixture['customer'].id}
+    form = forms.DeviceCreateForm(user=user, data=data)
+    assert form.is_valid() is False, (
+        "Should be false because duplicate devices are not allowed.")