Reuse Rack::Utils#build_nested_query

The rack package already provides a Rack::Utils#build_nested_query. So
the rack-test doesn't need to override or re-implement it. By reusing
the one from rack, this package will receive improvements as they are
made there.

For example, the upstream method has improved URL encoding since commit:
rack/rack@10864b6

Author: jdufresne

lib/rack/test/utils.rb

@@ -6,27 +6,25 @@ module Utils # :nodoc:
       include Rack::Utils
       extend self
 
-      # Build a query string for the given value and prefix. The value
-      # can be an array or hash of parameters.
-      def build_nested_query(value, prefix = nil)
-        case value
-        when Array
-          if value.empty?
-            "#{prefix}[]="
+      if Rack.release < '3.1.0'
+        # Build a query string for the given value and prefix. The value
+        # can be an array or hash of parameters.
+        def build_nested_query(value, prefix = nil)
+          case value
+          when Array
+            value.map { |v|
+              build_nested_query(v, "#{prefix}[]")
+            }.join("&")
+          when Hash
+            value.map { |k, v|
+              build_nested_query(v, prefix ? "#{prefix}[#{k}]" : k)
+            }.delete_if(&:empty?).join('&')
+          when nil
+            escape(prefix)
           else
-            prefix += "[]" unless unescape(prefix).end_with?('[]')
-            value.map do |v|
-              build_nested_query(v, prefix.to_s)
-            end.join('&')
+            raise ArgumentError, "value must be a Hash" if prefix.nil?
+            "#{escape(prefix)}=#{escape(value)}"
           end
-        when Hash
-          value.map do |k, v|
-            build_nested_query(v, prefix ? "#{prefix}[#{escape(k)}]" : escape(k))
-          end.join('&')
-        when NilClass
-          prefix.to_s
-        else
-          "#{prefix}=#{escape(value)}"
         end
       end
 

spec/rack/test/utils_spec.rb

@@ -5,8 +5,10 @@
 describe "Rack::Test::Utils#build_nested_query" do
   include Rack::Test::Utils
 
-  it 'converts empty strings to =' do
-    build_nested_query('').must_equal '='
+  it 'raises an error if string' do
+    proc do
+      build_nested_query('')
+    end.must_raise(ArgumentError, 'value must be a Hash')
   end
 
   it 'converts nil to an empty string' do
@@ -27,36 +29,36 @@
   end
 
   it 'converts empty arrays' do
-    build_nested_query(a: []).must_equal 'a[]='
+    build_nested_query(a: []).must_equal ''
   end
 
   it 'converts arrays with one element' do
-    build_nested_query(a: [1]).must_equal 'a[]=1'
+    build_nested_query(a: [1]).must_equal 'a%5B%5D=1'
   end
 
   it 'converts arrays with multiple elements' do
-    build_nested_query(a: [1, 2]).must_equal 'a[]=1&a[]=2'
+    build_nested_query(a: [1, 2]).must_equal 'a%5B%5D=1&a%5B%5D=2'
   end
 
   it "converts arrays with brackets '[]' in the name" do
-    build_nested_query('a[]' => [1, 2]).must_equal 'a%5B%5D=1&a%5B%5D=2'
+    build_nested_query('a[]' => [1, 2]).must_equal 'a%5B%5D%5B%5D=1&a%5B%5D%5B%5D=2'
   end
 
   it 'converts nested hashes' do
-    build_nested_query(a: { b: 1 }).must_equal 'a[b]=1'
+    build_nested_query(a: { b: 1 }).must_equal 'a%5Bb%5D=1'
   end
 
   it 'converts arrays nested in a hash' do
-    build_nested_query(a: { b: [1, 2] }).must_equal 'a[b][]=1&a[b][]=2'
+    build_nested_query(a: { b: [1, 2] }).must_equal 'a%5Bb%5D%5B%5D=1&a%5Bb%5D%5B%5D=2'
   end
 
   it 'converts arrays of hashes' do
-    build_nested_query(a: [{ b: 2 }, { c: 3 }]).must_equal 'a[][b]=2&a[][c]=3'
+    build_nested_query(a: [{ b: 2 }, { c: 3 }]).must_equal 'a%5B%5D%5Bb%5D=2&a%5B%5D%5Bc%5D=3'
   end
 
   it 'supports hash keys with empty arrays' do
     input = { collection: [] }
-    build_nested_query(input).must_equal 'collection[]='
+    build_nested_query(input).must_equal ''
   end
 end
 

spec/rack/test_spec.rb

@@ -192,7 +192,7 @@
 
   it 'accepts params and builds url encoded params for POST requests' do
     request '/foo', method: :post, params: { foo: { bar: '1' } }
-    last_request.env['rack.input'].read.must_equal 'foo[bar]=1'
+    last_request.env['rack.input'].read.must_equal 'foo%5Bbar%5D=1'
   end
 
   it 'accepts raw input in params for POST requests' do