RUBY-2123 Add test coverage for symbol round-tripping in Hash field values (#1681)

* RUBY-2123 Add test coverage for symbol round-tripping in Hash field values

* RUBY-2128 fix the test on JRuby

Co-authored-by: Oleg Pudeyev <[email protected]>

Author: p-mongo

spec/integration/bson_symbol_spec.rb

@@ -0,0 +1,34 @@
+require 'spec_helper'
+
+describe 'Symbol encoding to BSON' do
+  let(:value) { :foo }
+
+  let(:hash) do
+    {'foo' => value}
+  end
+
+  let(:serialized) do
+    hash.to_bson.to_s
+  end
+
+  let(:expected) do
+    "\x12\x00\x00\x00\x0Efoo\x00\x04\x00\x00\x00foo\x00\x00".force_encoding('binary')
+  end
+
+  it 'encodes symbol to BSON symbol' do
+    serialized.should == expected
+  end
+
+  it 'round-trips symbol values' do
+    buffer = BSON::ByteBuffer.new(serialized)
+    Hash.from_bson(buffer).should == hash
+  end
+
+  it 'round-trips symbol values using the same byte buffer' do
+    if BSON::Environment.jruby?
+      pending 'https://jira.mongodb.org/browse/RUBY-2128'
+    end
+
+    Hash.from_bson(hash.to_bson).should == hash
+  end
+end