Fix parser handling of endash'es

Use `unicode:characters_to_binary` instead of `list_to_binary`

Author: Josh Price

src/graphql_parser.yrl

@@ -210,7 +210,7 @@ Erlang code.
 
 extract_atom({Value, _Line}) -> Value.
 extract_token({_Token, _Line, Value}) -> list_to_binary(Value).
-extract_quoted_string_token({_Token, _Line, Value}) -> list_to_binary(lists:sublist(Value, 2, length(Value) - 2)).
+extract_quoted_string_token({_Token, _Line, Value}) -> unicode:characters_to_binary(lists:sublist(Value, 2, length(Value) - 2)).
 extract_integer({_Token, _Line, Value}) -> {Int, []} = string:to_integer(Value), Int.
 extract_float({_Token, _Line, Value}) -> {Float, []} = string:to_float(Value), Float.
 extract_boolean({_Token, _Line, "true"}) -> true;

test/graphql/lang/parser_test.exs

@@ -10,6 +10,11 @@ defmodule GraphQL.Lang.Parser.ParserTest do
     assert_parse "{}", %{errors: [%{"message" => "GraphQL: syntax error before: '}' on line 1", "line_number" => 1}]}, :error
   end
 
+  test "Handle unicode in string values" do
+    assert_parse ~S[{ f(a: "é")}], %{definitions: [%{kind: :OperationDefinition, loc: %{start: 0}, operation: :query, selectionSet: %{kind: :SelectionSet, loc: %{start: 0}, selections: [%{arguments: [%{kind: :Argument, loc: %{start: 0}, name: %{kind: :Name, loc: %{start: 0}, value: "a"}, value: %{kind: :StringValue, loc: %{start: 0}, value: "é"}}], kind: :Field, loc: %{start: 0}, name: %{kind: :Name, loc: %{start: 0}, value: "f"}}]}}], kind: :Document, loc: %{start: 0}}
+    assert_parse ~S[{ f(a: "–")}], %{definitions: [%{kind: :OperationDefinition, loc: %{start: 0}, operation: :query, selectionSet: %{kind: :SelectionSet, loc: %{start: 0}, selections: [%{arguments: [%{kind: :Argument, loc: %{start: 0}, name: %{kind: :Name, loc: %{start: 0}, value: "a"}, value: %{kind: :StringValue, loc: %{start: 0}, value: "–"}}], kind: :Field, loc: %{start: 0}, name: %{kind: :Name, loc: %{start: 0}, value: "f"}}]}}], kind: :Document, loc: %{start: 0}}
+  end
+
   test "simple selection set" do
     assert_parse "{ hero }",
     %{kind: :Document,