allow headers and env to be passed in `IntegrationTest`.

Closes #6513.

1 files changed, 15 insertions, 1 deletions

diff --git a/actionpack/lib/action_dispatch/http/headers.rb b/actionpack/lib/action_dispatch/http/headers.rb
index ecf050a869..3f3f71b280 100644
--- a/actionpack/lib/action_dispatch/http/headers.rb
+++ b/actionpack/lib/action_dispatch/http/headers.rb
@@ -12,9 +12,11 @@ module ActionDispatch
       HEADER_REGEXP = /\A[A-Za-z-]+\z/
 
       include Enumerable
+      attr_reader :env
 
       def initialize(env = {})
-        @env = env
+        @env = {}
+        merge!(env)
       end
 
       def [](key)
@@ -36,6 +38,18 @@ module ActionDispatch
         @env.each(&block)
       end
 
+      def merge(headers_or_env)
+        headers = Http::Headers.new(env.dup)
+        headers.merge!(headers_or_env)
+        headers
+      end
+
+      def merge!(headers_or_env)
+        headers_or_env.each do |key, value|
+          self[env_name(key)] = value
+        end
+      end
+
       private
       def env_name(key)
         if key =~ HEADER_REGEXP