_path helpers are no longer available in mailers

https://github.com/rails/rails/pull/15840

spec/dummy/app/views/posts/_post.html.erb

@@ -20,14 +20,16 @@
   <dt>Helpers from the controller:</dt>
   <dd id="goodnight_moon"><%= post.goodnight_moon %></dd>
 
-  <dt>Path with decorator:</dt>
-  <dd id="path_with_decorator"><%= post_path(post) %></dd>
+  <% unless defined? mailer %>
+    <dt>Path with decorator:</dt>
+    <dd id="path_with_decorator"><%= post_url(post) %></dd>
 
-  <dt>Path with model:</dt>
-  <dd id="path_with_model"><%= post.path_with_model %></dd>
+    <dt>Path with model:</dt>
+    <dd id="path_with_model"><%= post.path_with_model %></dd>
 
-  <dt>Path with id:</dt>
-  <dd id="path_with_id"><%= post.path_with_id %></dd>
+    <dt>Path with id:</dt>
+    <dd id="path_with_id"><%= post.path_with_id %></dd>
+  <% end %>
 
   <dt>URL with decorator:</dt>
   <dd id="url_with_decorator"><%= post_url(post) %></dd>

spec/dummy/spec/mailers/post_mailer_spec.rb

@@ -10,14 +10,6 @@ describe PostMailer do
       expect(email_body).to have_content "Today"
     end
 
-    it "can use path helpers with a model" do
-      expect(email_body).to have_css "#path_with_model", text: "/en/posts/#{post.id}"
-    end
-
-    it "can use path helpers with an id" do
-      expect(email_body).to have_css "#path_with_id", text: "/en/posts/#{post.id}"
-    end
-
     it "can use url helpers with a model" do
       expect(email_body).to have_css "#url_with_model", text: "http://www.example.com:12345/en/posts/#{post.id}"
     end

spec/integration/integration_spec.rb

@@ -38,16 +38,19 @@ app.start_server do
         expect(page).to have_text("Goodnight, moon!").in("#goodnight_moon")
       end
 
-      it "can be passed to path helpers" do
-        expect(page).to have_text("/en/posts/1").in("#path_with_decorator")
-      end
+      # _path helpers aren't available in mailers
+      if type == :view
+        it "can be passed to path helpers" do
+          expect(page).to have_text("/en/posts/1").in("#path_with_decorator")
+        end
 
-      it "can use path helpers with a model" do
-        expect(page).to have_text("/en/posts/1").in("#path_with_model")
-      end
+        it "can use path helpers with a model" do
+          expect(page).to have_text("/en/posts/1").in("#path_with_model")
+        end
 
-      it "can use path helpers with an id" do
-        expect(page).to have_text("/en/posts/1").in("#path_with_id")
+        it "can use path helpers with an id" do
+          expect(page).to have_text("/en/posts/1").in("#path_with_id")
+        end
       end
 
       it "can be passed to url helpers" do