Ensure that project environment names are unique

atst/forms/new_project.py

@@ -1,7 +1,7 @@
 from flask_wtf import Form
 from wtforms.fields import StringField, TextAreaField, FieldList
 from wtforms.validators import Required
-from atst.forms.validators import ListItemRequired
+from atst.forms.validators import ListItemRequired, ListItemsUnique
 
 
 class NewProjectForm(Form):
@@ -12,7 +12,10 @@ class NewProjectForm(Form):
     description = TextAreaField(label="Description", validators=[Required()])
     environment_names = FieldList(
         StringField(label="Environment Name"),
-        validators=[ListItemRequired(message="Provide at least one environment name.")],
+        validators=[
+            ListItemRequired(message="Provide at least one environment name."),
+            ListItemsUnique(message="Environment names must be unique."),
+        ],
     )
 
     @property

atst/forms/validators.py

@@ -60,3 +60,12 @@ def ListItemRequired(message="Please provide at least one.", empty_values=("", N
             raise ValidationError(message)
 
     return _list_item_required
+
+
+def ListItemsUnique(message="Items must be unique"):
+    def _list_items_unique(form, field):
+        sorted_values = sorted(v for v in field.data)
+        if sorted_values != sorted(set(sorted_values)):
+            raise ValidationError(message)
+
+    return _list_items_unique

tests/forms/test_validators.py

@@ -1,7 +1,7 @@
 from wtforms.validators import ValidationError
 import pytest
 
-from atst.forms.validators import Alphabet, IsNumber, PhoneNumber
+from atst.forms.validators import Alphabet, IsNumber, PhoneNumber, ListItemsUnique
 
 
 class TestIsNumber:
@@ -51,3 +51,18 @@ class TestAlphabet:
         dummy_field.data = invalid
         with pytest.raises(ValidationError):
             validator(dummy_form, dummy_field)
+
+
+class TestListItemsUnique:
+    @pytest.mark.parametrize("valid", [["a", "aa", "aaa"], ["one", "two", "three"]])
+    def test_ListItemsUnique_allows_unique_items(self, valid, dummy_form, dummy_field):
+        validator = ListItemsUnique()
+        dummy_field.data = valid
+        validator(dummy_form, dummy_field)
+
+    @pytest.mark.parametrize("invalid", [["a", "a", "a"], ["one", "two", "two", "three"]])
+    def test_ListItemsUnique_rejects_non_letters(self, invalid, dummy_form, dummy_field):
+        validator = ListItemsUnique()
+        dummy_field.data = invalid
+        with pytest.raises(ValidationError):
+            validator(dummy_form, dummy_field)