Change translation key of submit_tag from module_name_class_name to module_name/class_name

Currently submit_tag value translation does not support i18n key style
locale key.
It confuses me a bit because many other components support i18n key
style locale key.
I added i18n key style locale key support to submit tag.

actionview/CHANGELOG.md

 ## Rails 6.0.0.alpha (Unreleased) ##
 
+*   Change translation key of `submit_tag` from `module_name_class_name` to `module_name/class_name`.
+
+    *Rui Onodera*
+
 *   Rails 6 requires Ruby 2.4.1 or newer.
 
     *Jeremy Daer*

actionview/lib/action_view/helpers/form_helper.rb

@@ -2266,7 +2266,12 @@ def submit_default_value
           end
 
           defaults = []
-          defaults << :"helpers.submit.#{object_name}.#{key}"
+          # Object is a model and it is not overwritten by as and scope option.
+          if object.respond_to?(:model_name) && object_name.to_s == model.downcase
+            defaults << :"helpers.submit.#{object.model_name.i18n_key}.#{key}"
+          else
+            defaults << :"helpers.submit.#{object_name}.#{key}"
+          end
           defaults << :"helpers.submit.#{key}"
           defaults << "#{key.to_s.humanize} #{model}"
 

actionview/test/template/form_helper/form_with_test.rb

@@ -190,6 +190,9 @@ def form_with(*)
           submit: "Save changes",
           another_post: {
             update: "Update your %{model}"
+          },
+          "blog/post": {
+            update: "Update your %{model}"
           }
         }
       }
@@ -962,7 +965,7 @@ def test_submit_without_object_and_locale_strings
     end
   end
 
-  def test_submit_with_object_and_nested_lookup
+  def test_submit_with_object_which_is_overwritten_by_scope_option
     with_locale :submit do
       form_with(model: @post, scope: :another_post) do |f|
         concat f.submit
@@ -976,6 +979,21 @@ def test_submit_with_object_and_nested_lookup
     end
   end
 
+  def test_submit_with_object_which_is_namespaced
+    blog_post = Blog::Post.new("And his name will be forty and four.", 44)
+    with_locale :submit do
+      form_with(model: blog_post) do |f|
+        concat f.submit
+      end
+
+      expected = whole_form("/posts/44", method: "patch") do
+        "<input name='commit' data-disable-with='Update your Post' type='submit' value='Update your Post' />"
+      end
+
+      assert_dom_equal expected, output_buffer
+    end
+  end
+
   def test_fields_with_attributes_not_on_model
     form_with(model: @post) do |f|
       concat f.fields(:comment) { |c|

actionview/test/template/form_helper_test.rb

@@ -68,6 +68,9 @@ def form_for(*)
           submit: "Save changes",
           another_post: {
             update: "Update your %{model}"
+          },
+          "blog/post": {
+            update: "Update your %{model}"
           }
         }
       }
@@ -2271,7 +2274,7 @@ def test_submit_without_object_and_locale_strings
     end
   end
 
-  def test_submit_with_object_and_nested_lookup
+  def test_submit_with_object_which_is_overwritten_by_as_option
     with_locale :submit do
       form_for(@post, as: :another_post) do |f|
         concat f.submit
@@ -2285,6 +2288,21 @@ def test_submit_with_object_and_nested_lookup
     end
   end
 
+  def test_submit_with_object_which_is_namespaced
+    blog_post = Blog::Post.new("And his name will be forty and four.", 44)
+    with_locale :submit do
+      form_for(blog_post) do |f|
+        concat f.submit
+      end
+
+      expected = whole_form("/posts/44", "edit_post_44", "edit_post", method: "patch") do
+        "<input name='commit' data-disable-with='Update your Post' type='submit' value='Update your Post' />"
+      end
+
+      assert_dom_equal expected, output_buffer
+    end
+  end
+
   def test_nested_fields_for
     @comment.body = "Hello World"
     form_for(@post) do |f|