Respect form_class argument (#26)

Fixes #25

django_bleach/models.py

@@ -29,10 +29,10 @@ def __init__(self, allowed_tags=None, allowed_attributes=None,
         if strip_comments:
             self.bleach_kwargs["strip_comments"] = strip_comments
 
-    def formfield(self, **kwargs):
+    def formfield(self, form_class=forms.BleachField, **kwargs):
         """ Makes the field for a ModelForm """
 
-        # If field doesn't have any choice return BleachField
+        # If field doesn't have any choices add kwargs expected by BleachField.
         if not self.choices:
             kwargs.update({
                 "max_length": self.max_length,
@@ -44,9 +44,8 @@ def formfield(self, **kwargs):
                 "strip_comments": self.bleach_kwargs.get("strip_comments"),
                 "required": not self.blank,
             })
-            return forms.BleachField(**kwargs)
 
-        return super(BleachField, self).formfield(**kwargs)
+        return super(BleachField, self).formfield(form_class=form_class, **kwargs)
 
     def pre_save(self, model_instance, add):
         data = getattr(model_instance, self.attname)

django_bleach/tests/test_modelformfield.py

@@ -63,3 +63,29 @@ def test_required_field(self):
         Check for the required flag on fields
         """
         self.assertEqual(self.form_field.required, True)
+
+
+class CustomBleachedFormField(bleach_forms.BleachField):
+    ...
+
+
+class OverriddenBleachContentModelForm(forms.ModelForm):
+    class Meta:
+        model = BleachContent
+        fields = '__all__'
+        field_classes = {
+            "content": CustomBleachedFormField,
+        }
+
+
+class TestModelFormFieldOverrides(TestCase):
+
+    def setUp(self):
+        model_form = OverriddenBleachContentModelForm()
+        self.form_field = model_form.fields['content']
+
+    def test_formfield_type(self):
+        """
+        Check content's form field is instance of CustomBleachedFormField.
+        """
+        self.assertIsInstance(self.form_field, CustomBleachedFormField)