created apps.dashboard.forms & commensurate apps.dashboard.tests.test_forms; new ItemForm() ModelForm & EMPTY_ITEM_ERROR constant

src/apps/dashboard/forms.py

@@ -0,0 +1,18 @@
+from django import forms
+from .models import Item
+
+EMPTY_ITEM_ERROR = "You can't have an empty list item"
+
+class ItemForm(forms.models.ModelForm):
+    class Meta:
+        model = Item
+        fields = ("text",)
+        widgets = {
+            "text": forms.widgets.TextInput(
+                attrs={
+                    "placeholder": "Enter a to-do item",
+                    "class": "form-control form-control-lg",
+                }
+            ),
+        }
+        error_messages = {"text": {"required": EMPTY_ITEM_ERROR}}

src/apps/dashboard/tests/test_forms.py

@@ -0,0 +1,18 @@
+from django.test import TestCase
+from ..forms import EMPTY_ITEM_ERROR, ItemForm
+
+class ItemFormTest(TestCase):
+    def test_form_item_has_placeholder_and_css_classes(self):
+        form = ItemForm()
+        rendered = form.as_p()
+        self.assertIn('placeholder="Enter a to-do item"', rendered)
+        self.assertIn('class="form-control form-control-lg"', rendered)
+
+    def test_form_validation_for_blank_items(self):
+        form = ItemForm(data={"text": ""})
+        form.save()
+
+    def test_form_validation_for_blank_items(self):
+        form = ItemForm(data={"text": ""})
+        self.assertFalse(form.is_valid())
+        self.assertEqual(form.errors["text"], [EMPTY_ITEM_ERROR])