Fix parser so it properly parses headers

lib/http/response/parser.rb

@@ -49,14 +49,17 @@ def status_code
       #
 
       def on_header_field(_response, field)
-        @field = field
+        append_header if @reading_header_value
+        @field << field
       end
 
       def on_header_value(_response, value)
-        @headers.add(@field, value) if @field
+        @reading_header_value = true
+        @field_value << value
       end
 
       def on_headers_complete(_reposse)
+        append_header if @reading_header_value
         @finished[:headers] = true
       end
 
@@ -89,15 +92,26 @@ def on_message_complete(_response)
       def reset
         @state.reset!
 
-        @finished = Hash.new(false)
-        @headers  = HTTP::Headers.new
-        @field    = nil
-        @chunk    = nil
+        @finished             = Hash.new(false)
+        @headers              = HTTP::Headers.new
+        @reading_header_value = false
+        @field                = +""
+        @field_value          = +""
+        @chunk                = nil
       end
 
       def finished?
         @finished[:message]
       end
+
+      private
+
+      def append_header
+        @headers.add(@field, @field_value)
+        @reading_header_value = false
+        @field_value          = +""
+        @field                = +""
+      end
     end
   end
 end

spec/lib/http/response/parser_spec.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+RSpec.describe HTTP::Response::Parser do
+  subject(:parser) { described_class.new }
+  let(:raw_response) do
+    "HTTP/1.1 200 OK\r\nContent-Length: 2\r\nContent-Type: application/json\r\nMyHeader: val\r\nEmptyHeader: \r\n\r\n{}"
+  end
+  let(:expected_headers) do
+    {
+      "Content-Length" => "2",
+      "Content-Type"   => "application/json",
+      "MyHeader"       => "val",
+      "EmptyHeader"    => ""
+    }
+  end
+  let(:expected_body) { "{}" }
+
+  before do
+    parts.each { |part| subject.add(part) }
+  end
+
+  context "whole response in one part" do
+    let(:parts) { [raw_response] }
+
+    it "parses headers" do
+      expect(subject.headers.to_h).to eq(expected_headers)
+    end
+
+    it "parses body" do
+      expect(subject.read(expected_body.size)).to eq(expected_body)
+    end
+  end
+
+  context "response in many parts" do
+    let(:parts) { raw_response.split(//) }
+
+    it "parses headers" do
+      expect(subject.headers.to_h).to eq(expected_headers)
+    end
+
+    it "parses body" do
+      expect(subject.read(expected_body.size)).to eq(expected_body)
+    end
+  end
+end