Add memory consumption test cases

json-streamer.gemspec

@@ -26,6 +26,8 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "rspec", "~> 3.0"
   spec.add_development_dependency "coveralls"
   spec.add_development_dependency "ndhash"
+  spec.add_development_dependency "sys-proctable"
+  spec.add_development_dependency "get_process_mem"
 
   spec.add_dependency "json-stream"
 end

spec/json/streamer/json_streamer_spec.rb

@@ -1,4 +1,7 @@
 require 'spec_helper'
+require 'json/stream'
+require 'get_process_mem'
+
 
 RSpec.describe Json::Streamer::JsonStreamer do
 
@@ -283,6 +286,50 @@
       end
     end
 
+    context 'Big JSON array parsed with JSON::Stream', :speed => 'slow', :type => 'memory' do
+      it 'should increase memory consumption' do
+
+        json_array_size = 2**16
+        hash = Array.new(json_array_size) {@example_hash}
+        json_file_mock = StringIO.new(JSON.generate(hash))
+
+        memory_consumption_before_parsing = GetProcessMem.new.mb
+        obj = JSON::Stream::Parser.parse(json_file_mock)
+        memory_consumption_after_parsing = GetProcessMem.new.mb
+
+        p "Number of elements: #{json_array_size}"
+        p "Memory consumption before and after parsing: #{memory_consumption_before_parsing.round} MB -  #{memory_consumption_after_parsing.round} MB"
+        expect(memory_consumption_after_parsing).to be > 1.5 * memory_consumption_before_parsing
+        p "With JSON::Stream memory consumption increased with at least 150% during processing."
+      end
+    end
+
+    context 'Big JSON array parsed with JSON::Streamer', :speed => 'slow', :type => 'memory' do
+      it 'should NOT increase memory consumption'  do
+
+        json_array_size = 2**18
+        hash = Array.new(json_array_size) {@example_hash}
+        json_file_mock = StringIO.new(JSON.generate(hash))
+
+        memory_consumption_before_parsing = GetProcessMem.new.mb
+
+        streamer = Json::Streamer::JsonStreamer.new(json_file_mock, 10)
+        object_count = 0
+        streamer.get(nesting_level:1) do |object|
+          expect(object).to eq(@example_hash)
+          object_count += 1
+        end
+        expect(object_count).to eq(json_array_size)
+
+        memory_consumption_after_parsing = GetProcessMem.new.mb
+
+        p "Number of elements: #{json_array_size}"
+        p "Memory consumption before and after parsing: #{memory_consumption_before_parsing.round} MB -  #{memory_consumption_after_parsing.round} MB"
+        expect(memory_consumption_after_parsing).to be < 1.1 * memory_consumption_before_parsing
+        p "With JSON::Streamer memory consumption did not increase significantly during processing."
+      end
+    end
+
   end
 
 end