Create deflated body right before streaming starts

This makes it easier for 3rd-party libraries to inspect and log the
request body, because they can rely on HTTP::Request#body always
returning a HTTP::Request::Body object, instead of a DeflatedBody object
when :auto_deflate is enabled.

We also define HTTP::Request::Body#== for easier testing.

lib/http/request.rb

@@ -86,7 +86,8 @@ def initialize(opts)
       raise(UnsupportedSchemeError, "unknown scheme: #{scheme}") unless SCHEMES.include?(@scheme)
 
       @proxy   = opts[:proxy] || {}
-      @body    = request_body(opts[:body], opts)
+      @body    = Request::Body.new(opts[:body])
+      @deflate = opts[:auto_deflate]
       @version = opts[:version] || "1.1"
       @headers = HTTP::Headers.coerce(opts[:headers] || {})
 
@@ -100,18 +101,20 @@ def redirect(uri, verb = @verb)
       headers.delete(Headers::HOST)
 
       self.class.new(
-        :verb    => verb,
-        :uri     => @uri.join(uri),
-        :headers => headers,
-        :proxy   => proxy,
-        :body    => body,
-        :version => version
+        :verb         => verb,
+        :uri          => @uri.join(uri),
+        :headers      => headers,
+        :proxy        => proxy,
+        :body         => body.source,
+        :auto_deflate => @deflate,
+        :version      => version
       )
     end
 
     # Stream the request to a socket
     def stream(socket)
       include_proxy_headers if using_proxy? && !@uri.https?
+      body = @deflate ? @deflate.deflated_body(self.body) : self.body
       Request::Writer.new(socket, body, headers, headline).stream
     end
 
@@ -186,13 +189,6 @@ def socket_port
 
     private
 
-    # Transforms body to an object suitable for streaming.
-    def request_body(body, opts)
-      body = Request::Body.new(body) unless body.is_a?(Request::Body)
-      body = opts[:auto_deflate].deflated_body(body) if opts[:auto_deflate]
-      body
-    end
-
     # @!attribute [r] host
     #   @return [String]
     def_delegator :@uri, :host

lib/http/request/body.rb

@@ -40,6 +40,11 @@ def each(&block)
         end
       end
 
+      # Request bodies are equivalent when they have the same source.
+      def ==(other)
+        self.class == other.class && self.source == other.source # rubocop:disable Style/RedundantSelf
+      end
+
       private
 
       def validate_source_type!

spec/lib/http/request/body_spec.rb

@@ -141,4 +141,33 @@
       end
     end
   end
+
+  describe "#==" do
+    context "when sources are equivalent" do
+      let(:body1) { HTTP::Request::Body.new("content") }
+      let(:body2) { HTTP::Request::Body.new("content") }
+
+      it "returns true" do
+        expect(body1).to eq body2
+      end
+    end
+
+    context "when sources are not equivalent" do
+      let(:body1) { HTTP::Request::Body.new("content") }
+      let(:body2) { HTTP::Request::Body.new(nil) }
+
+      it "returns false" do
+        expect(body1).not_to eq body2
+      end
+    end
+
+    context "when objects are not of the same class" do
+      let(:body1) { HTTP::Request::Body.new("content") }
+      let(:body2) { "content" }
+
+      it "returns false" do
+        expect(body1).not_to eq body2
+      end
+    end
+  end
 end