Pass InlinePanel heading rather than label to use as the label for comparisons

Conventionally `label` is singular (used on individual forms as "Speaker 1", "Speaker 2" etc as well as the "Add speaker" button), while `heading` is plural ("Speakers" or "Speaker lineup", used as the main heading for the list). The plural is most appropriate for the comparison view.

Also fix the test for MultipleChooserPanel, which was copied across from the InlinePanel test without actually setting a label/heading on the panel.

wagtail/admin/panels/inline_panel.py

@@ -150,7 +150,7 @@ class InlinePanel(Panel):
                     compare.ChildRelationComparison,
                     self.panel.db_field,
                     field_comparisons,
-                    label=self.label,
+                    label=self.heading,
                 )
             ]
 

wagtail/admin/tests/pages/test_edit_page.py

@@ -167,7 +167,7 @@ class TestPageEdit(WagtailTestUtils, TestCase):
             response,
             '<label class="w-field__label" for="id_speakers-__prefix__-last_name" id="id_speakers-__prefix__-last_name-label">',
         )
-        self.assertContains(response, "Add speakers")
+        self.assertContains(response, "Add speaker")
         self.assertContains(response, "Put the keynote speaker first")
 
         # Test MultiFieldPanel help text

wagtail/admin/tests/test_edit_handlers.py

@@ -1569,7 +1569,7 @@ class TestInlinePanelGetComparison(TestCase):
         self.request.user = user
 
     def test_get_comparison(self):
-        # Test whether the InlinePanel passes it's label in get_comparison
+        # Test whether the InlinePanel passes its heading as the label in get_comparison
 
         page = Page.objects.get(id=4).specific
         comparison = (
@@ -1580,7 +1580,7 @@ class TestInlinePanelGetComparison(TestCase):
 
         comparison = [comp(page, page) for comp in comparison]
         field_labels = [comp.field_label() for comp in comparison]
-        self.assertIn("Speakers", field_labels)
+        self.assertIn("Speaker lineup", field_labels)
 
 
 class TestInlinePanelRelatedModelPanelConfigChecks(TestCase):
@@ -2078,7 +2078,7 @@ class TestMultipleChooserPanelGetComparison(TestCase):
         parent_page.add_child(instance=self.page)
 
     def test_get_comparison(self):
-        # Test whether the InlinePanel passes it's label in get_comparison
+        # Test whether the MultipleChooserPanel passes its heading in get_comparison
 
         comparison = (
             self.page.get_edit_handler()

wagtail/test/testapp/models.py

@@ -434,7 +434,7 @@ class EventPage(Page):
         FieldPanel("body"),
         InlinePanel(
             "speakers",
-            label="Speakers",
+            label="Speaker",
             heading="Speaker lineup",
             help_text="Put the keynote speaker first",
         ),
@@ -2359,7 +2359,9 @@ class ModelWithNullableParentalKey(models.Model):
 
 class GalleryPage(Page):
     content_panels = Page.content_panels + [
-        MultipleChooserPanel("gallery_images", chooser_field_name="image")
+        MultipleChooserPanel(
+            "gallery_images", heading="Gallery images", chooser_field_name="image"
+        )
     ]