Liquid::Template.parse(text) error in rspec after ver 5.6~

only in rspec, the method has error.
works fine in application env, or rails console.

rspec result:

Failure/Error: template = Liquid::Template.parse(text.to_s)

     NoMethodError:
       undefined method `peek_byte' for #<StringScanner 0/26 @ "Hello...">
     # /usr/local/bundle/gems/liquid-5.6.4/lib/liquid/tokenizer.rb:74:in `next_token'
     # /usr/local/bundle/gems/liquid-5.6.4/lib/liquid/tokenizer.rb:65:in `shift_normal'
     # /usr/local/bundle/gems/liquid-5.6.4/lib/liquid/tokenizer.rb:57:in `tokenize'
     # /usr/local/bundle/gems/liquid-5.6.4/lib/liquid/tokenizer.rb:33:in `initialize'
     # /usr/local/bundle/gems/liquid-5.6.4/lib/liquid/parse_context.rb:45:in `new'
     # /usr/local/bundle/gems/liquid-5.6.4/lib/liquid/parse_context.rb:45:in `new_tokenizer'
     # /usr/local/bundle/gems/liquid-5.6.4/lib/liquid/template.rb:105:in `parse'
     # /usr/local/bundle/gems/liquid-5.6.4/lib/liquid/template.rb:85:in `parse'
...

downgrading to 5.5~, error has gone.

Start with Liquid::Template.parse and the tokenizer failure at lib/liquid/tokenizer.rb:74, reproducing the reported call under RSpec with Liquid 5.6.4 and then comparing it with 5.5. Confirm that parsing the same text works outside RSpec and that the fix removes the peek_byte error without regressing parsing.