Fix array of cookies in response containing a blank cookie

Without the fix, the blank cookie is compared and since it has no name
the comparison fails on name.downcase. Rather than correct it there, this
expands the processing of merged cookies to remove blank cookies not just
in strings, but also in arrays.

lib/rack/test/cookie_jar.rb

@@ -12,7 +12,7 @@ class Cookie # :nodoc:
 
       # The name of the cookie, will be a string
       attr_reader :name
-      
+
       # The value of the cookie, will be a string or nil if there is no value.
       attr_reader :value
 
@@ -183,12 +183,10 @@ def delete(name)
       def merge(raw_cookies, uri = nil)
         return unless raw_cookies
 
-        if raw_cookies.is_a? String
-          raw_cookies = raw_cookies.split("\n")
-          raw_cookies.reject!(&:empty?)
-        end
+        raw_cookies = raw_cookies.split("\n") if raw_cookies.is_a? String
 
         raw_cookies.each do |raw_cookie|
+          next if raw_cookie.empty?
           cookie = Cookie.new(raw_cookie, uri, @default_host)
           self << cookie if cookie.valid?(uri)
         end

spec/rack/test/cookie_jar_spec.rb

@@ -67,4 +67,17 @@
     jar.merge('c=d; domain=example.org; secure', URI.parse('/'))
     jar.to_hash.must_equal 'a' => 'b'
   end
+
+  it '#merge ignores empty cookies in cookie strings' do
+    jar = Rack::Test::CookieJar.new
+    jar.merge('', URI.parse('/'))
+    jar.merge("\nc=d")
+    jar.to_hash.must_equal 'c' => 'd'
+  end
+
+  it '#merge ignores empty cookies in cookie arrays' do
+    jar = Rack::Test::CookieJar.new
+    jar.merge(['', 'c=d'], URI.parse('/'))
+    jar.to_hash.must_equal 'c' => 'd'
+  end
 end