Add 'display_control' option to view configs to allow them to toggle …

…on/off visibility in the view type widget

app/helpers/blacklight/configuration_helper_behavior.rb

@@ -134,6 +134,13 @@ def document_index_views
     end
   end
 
+  # filter #document_index_views to just views that should display in the view type control
+  def document_index_view_controls
+    document_index_views.select do |_k, config|
+      config.display_control.nil? || blacklight_configuration_context.evaluate_configuration_conditional(config.display_control)
+    end
+  end
+
   ##
   # Get the default index view type
   def default_document_index_view_type

app/views/catalog/_view_type_group.html.erb

@@ -2,7 +2,7 @@
 <div class="view-type">
   <span class="sr-only"><%= t('blacklight.search.view_title') %></span>
   <div class="view-type-group btn-group">
-    <%  document_index_views.each do |view, config| %>
+    <% document_index_view_controls.each do |view, config| %>
       <%= link_to url_for(search_state.to_h.merge(view: view)), title: view_label(view), class: "btn btn-secondary view-type-#{ view.to_s.parameterize } #{"active" if document_index_view_type == view}" do %>
         <%= render_view_type_group_icon view %>
         <span class="caption"><%= view_label(view) %></span>

spec/views/catalog/_view_type_group.html.erb_spec.rb

@@ -37,6 +37,21 @@
     expect(rendered).to have_selector('.view-type-c', :text => 'c')
   end
 
+  it "hides views that are set to not display" do
+    blacklight_config.configure do |config|
+      config.view.delete(:list)
+      config.view.a
+      config.view.b
+      config.view.b.display_control = false
+    end
+
+    render partial: 'catalog/view_type_group'
+
+    expect(rendered).to have_selector('.btn-group.view-type-group')
+    expect(rendered).to have_selector('.view-type-a', text: 'a')
+    expect(rendered).not_to have_selector('.view-type-b', text: 'b')
+  end
+
   it "sets the current view to 'active'" do
     blacklight_config.configure do |config|
       config.view.delete(:list)