Deprecate `request_via_redirect` method.

- Followup of https://github.com/rails/rails/issues/18693.
- I think we missed deprecating `request_via_redirect` in that pull
  request.
- Originally requested by DHH here
  https://github.com/rails/rails/issues/18333.

actionpack/lib/action_dispatch/testing/integration.rb

@@ -122,6 +122,7 @@ def follow_redirect!
       #     params: { ref_id: 14 },
       #     headers: { "X-Test-Header" => "testvalue" }
       def request_via_redirect(http_method, path, *args)
+        ActiveSupport::Deprecation.warn('`request_via_redirect` is deprecated and will be removed in Rails 5.1. Please use `follow_redirect!` manually after the request call for the same behavior.')
         process_with_kwargs(http_method, path, *args)
 
         follow_redirect! while redirect?
@@ -131,35 +132,35 @@ def request_via_redirect(http_method, path, *args)
       # Performs a GET request, following any subsequent redirect.
       # See +request_via_redirect+ for more information.
       def get_via_redirect(path, *args)
-        ActiveSupport::Deprecation.warn('`get_via_redirect` is deprecated and will be removed in Rails 5.1. Please use follow_redirect! manually after the request call for the same behavior.')
+        ActiveSupport::Deprecation.warn('`get_via_redirect` is deprecated and will be removed in Rails 5.1. Please use `follow_redirect!` manually after the request call for the same behavior.')
         request_via_redirect(:get, path, *args)
       end
 
       # Performs a POST request, following any subsequent redirect.
       # See +request_via_redirect+ for more information.
       def post_via_redirect(path, *args)
-        ActiveSupport::Deprecation.warn('`post_via_redirect` is deprecated and will be removed in Rails 5.1. Please use follow_redirect! manually after the request call for the same behavior.')
+        ActiveSupport::Deprecation.warn('`post_via_redirect` is deprecated and will be removed in Rails 5.1. Please use `follow_redirect!` manually after the request call for the same behavior.')
         request_via_redirect(:post, path, *args)
       end
 
       # Performs a PATCH request, following any subsequent redirect.
       # See +request_via_redirect+ for more information.
       def patch_via_redirect(path, *args)
-        ActiveSupport::Deprecation.warn('`patch_via_redirect` is deprecated and will be removed in Rails 5.1. Please use follow_redirect! manually after the request call for the same behavior.')
+        ActiveSupport::Deprecation.warn('`patch_via_redirect` is deprecated and will be removed in Rails 5.1. Please use `follow_redirect!` manually after the request call for the same behavior.')
         request_via_redirect(:patch, path, *args)
       end
 
       # Performs a PUT request, following any subsequent redirect.
       # See +request_via_redirect+ for more information.
       def put_via_redirect(path, *args)
-        ActiveSupport::Deprecation.warn('`put_via_redirect` is deprecated and will be removed in Rails 5.1. Please use follow_redirect! manually after the request call for the same behavior.')
+        ActiveSupport::Deprecation.warn('`put_via_redirect` is deprecated and will be removed in Rails 5.1. Please use `follow_redirect!` manually after the request call for the same behavior.')
         request_via_redirect(:put, path, *args)
       end
 
       # Performs a DELETE request, following any subsequent redirect.
       # See +request_via_redirect+ for more information.
       def delete_via_redirect(path, *args)
-        ActiveSupport::Deprecation.warn('`delete_via_redirect` is deprecated and will be removed in Rails 5.1. Please use follow_redirect! manually after the request call for the same behavior.')
+        ActiveSupport::Deprecation.warn('`delete_via_redirect` is deprecated and will be removed in Rails 5.1. Please use `follow_redirect!` manually after the request call for the same behavior.')
         request_via_redirect(:delete, path, *args)
       end
     end

actionpack/test/controller/integration_test.rb

@@ -35,7 +35,7 @@ def test_request_via_redirect_uses_given_method
     path = "/somepath"; args = {:id => '1'}; headers = {"X-Test-Header" => "testvalue"}
     assert_called_with @session, :process, [:put, path, params: args, headers: headers] do
       @session.stub :redirect?, false do
-        @session.request_via_redirect(:put, path, params: args, headers: headers)
+        assert_deprecated { @session.request_via_redirect(:put, path, params: args, headers: headers) }
       end
     end
   end
@@ -54,7 +54,7 @@ def test_request_via_redirect_follows_redirects
     value_series = [true, true, false]
     assert_called @session, :follow_redirect!, times: 2 do
       @session.stub :redirect?, ->{ value_series.shift } do
-        @session.request_via_redirect(:get, path, params: args, headers: headers)
+        assert_deprecated { @session.request_via_redirect(:get, path, params: args, headers: headers) }
       end
     end
   end
@@ -63,7 +63,9 @@ def test_request_via_redirect_returns_status
     path = "/somepath"; args = {:id => '1'}; headers = {"X-Test-Header" => "testvalue"}
     @session.stub :redirect?, false do
       @session.stub :status, 200 do
-        assert_equal 200, @session.request_via_redirect(:get, path, params: args, headers: headers)
+        assert_deprecated do
+          assert_equal 200, @session.request_via_redirect(:get, path, params: args, headers: headers)
+        end
       end
     end
   end