Add alt_text field for banner tile

CHANGES.rst

@@ -6,7 +6,8 @@ There's a frood who really knows where his towel is.
 1.6b6 (unreleased)
 ^^^^^^^^^^^^^^^^^^
 
-- Nothing changed yet.
+- Provide alternative text for image fields in tiles (closes `#628 <https://github.com/collective/collective.cover/issues/628>`_).
+  [hvelarde]
 
 
 1.6b5 (2017-11-21)

src/collective/cover/tests/test_banner_tile.py

@@ -3,6 +3,7 @@
 from collective.cover.tests.base import TestTileMixin
 from collective.cover.tiles.banner import BannerTile
 from collective.cover.tiles.banner import IBannerTile
+from lxml import etree
 from mock import Mock
 
 import unittest
@@ -96,10 +97,21 @@ def test_render_empty(self):
     def test_render_with_image(self):
         obj = self.portal['my-image']
         self.tile.populate_with_object(obj)
-        rendered = self.tile()
-        # the image is there and the alt attribute is set
-        self.assertIn('<img ', rendered)
-        self.assertIn('alt="This image was created for testing purposes"', rendered)
+        html = etree.HTML(self.tile())
+        img = html.find('*//img')
+        self.assertIsNotNone(img)
+        self.assertIn('alt', img.attrib)
+        self.assertEqual(
+            img.attrib['alt'], 'This image was created for testing purposes')
+
+        # set  alternate text
+        alt_text = u'Murciélago hindú'
+        self.tile.data['alt_text'] = alt_text
+        html = etree.HTML(self.tile())
+        img = html.find('*//img')
+        self.assertIsNotNone(img)
+        self.assertIn('alt', img.attrib)
+        self.assertEqual(img.attrib['alt'], alt_text)
 
     def test_render_with_link(self):
         obj = self.portal['my-link']

src/collective/cover/tiles/banner.py

@@ -3,7 +3,9 @@
 from collective.cover import _
 from collective.cover.tiles.base import IPersistentCoverTile
 from collective.cover.tiles.base import PersistentCoverTile
+from collective.cover.tiles.configuration_view import IDefaultConfigureForm
 from collective.cover.utils import get_types_use_view_action_in_listings
+from plone.autoform import directives as form
 from plone.namedfile import field
 from plone.tiles.interfaces import ITileDataManager
 from plone.uuid.interfaces import IUUID
@@ -25,12 +27,24 @@ class IBannerTile(IPersistentCoverTile):
         required=False,
     )
 
-    remote_url = schema.TextLine(
+    # form.no_omit('alt_text')
+    form.omitted(IDefaultConfigureForm, 'alt_text')
+    alt_text = schema.TextLine(
+        title=_(
+            u'label_alt_text',
+            default=u'Alternative Text'),
+        description=_(
+            u'help_alt_text',
+            default=u'Provides a textual alternative to non-text content in web pages.'),  # noqa E501
+        required=False,
+    )
+
+    remote_url = schema.TextLine(  # FIXME: this must be schema.URI()
         title=_(u'URL'),
         required=False,
     )
 
-    uuid = schema.TextLine(
+    uuid = schema.TextLine(  # FIXME: this must be schema.ASCIILine()
         title=_(u'UUID'),
         required=False,
         readonly=True,
@@ -82,6 +96,8 @@ def populate_with_object(self, obj):
             'description': description,
             'uuid': IUUID(obj),
             'image': image,
+            # FIXME: https://github.com/collective/collective.cover/issues/778
+            'alt_text': description or title,
             'remote_url': remote_url,
         })
 
@@ -110,5 +126,6 @@ def htmltag(self):
 
     @property
     def alt(self):
-        """Return the alt attribute for the image."""
-        return self.data.get('description') or self.data.get('title')
+        """Return alternative text dealing with form init issues."""
+        alt_text = self.data['alt_text']
+        return alt_text if alt_text is not None else u''