Ensure rack_test driver processes 307/308 redirects correctly

lib/capybara/rack_test/browser.rb

@@ -44,7 +44,13 @@ class Capybara::RackTest::Browser
     return unless driver.follow_redirects?
 
     driver.redirect_limit.times do
-      process(:get, last_response["Location"], {}, env) if last_response.redirect?
+      if last_response.redirect?
+        if [307, 308].include? last_response.status
+          process(last_request.request_method, last_response["Location"], last_request.params, env)
+        else
+          process(:get, last_response["Location"], {}, env)
+        end
+      end
     end
     raise Capybara::InfiniteRedirectError, "redirected more than #{driver.redirect_limit} times, check for infinite redirects." if last_response.redirect?
   end

lib/capybara/spec/session/click_button_spec.rb

@@ -396,6 +396,11 @@ Capybara::SpecHelper.spec '#click_button' do
     expect(@session.current_url).to match(%r{/landed$})
   end
 
+  it "should follow redirects that maintain method" do
+    @session.click_button('Go 307')
+    expect(@session).to have_content('You post landed: 307')
+  end
+
   it "should post pack to the same URL when no action given" do
     @session.visit('/postback')
     @session.click_button('With no action')

lib/capybara/spec/test_app.rb

@@ -38,6 +38,10 @@ class TestApp < Sinatra::Base
     redirect '/landed'
   end
 
+  post '/redirect_307' do
+    redirect '/landed', 307
+  end
+
   get '/referer_base' do
     '<a href="/get_referer">direct link</a>' \
     '<a href="/redirect_to_get_referer">link via redirect</a>' \
@@ -69,6 +73,10 @@ class TestApp < Sinatra::Base
     "You landed"
   end
 
+  post '/landed' do
+    "You post landed: #{params.dig(:form, 'data')}"
+  end
+
   get '/with-quotes' do
     %q("No," he said, "you can't do that.")
   end

lib/capybara/spec/views/form.erb

@@ -554,6 +554,13 @@ New line after and before textarea tag
   </p>
 </form>
 
+<form action="/redirect_307" method="post">
+  <input type="hidden" name="form[data]" value="307"/>
+  <p>
+    <input type="submit" value="Go 307"/>
+  </p>
+</form>
+
 <form action="/form" method="post">
   <p>
     <label for="html5_email">Html5 Email</label>