[sergio-bobillier]

Simplifies the logic that ensures that the class has a single top-level clause. This simplification also gets rid of a re-assignment of the same top-level clause when #bool was called multiple times.

[julian711]

Thanks for the simplification, behavior looks preserved. Two optional test-coverage suggestions for spec/jay_api/elasticsearch/query_builder/query_clauses_spec.rb (the spec isn't touched by this PR, so they're posted here rather than inline):

1. #<< when a Bool is already the top-level clause

<< now goes through the same setter, so it should raise after bool. This case isn't covered yet:

context 'when a boolean clause has already been added' do
  before { query_clauses.bool }

  it 'raises a JayAPI::Elasticsearch::QueryBuilder::Errors::QueryBuilderError' do
    expect { method_call }.to raise_error(
      JayAPI::Elasticsearch::QueryBuilder::Errors::QueryBuilderError,
      'Queries can only have one top-level query clause, to use multiple ' \
      'clauses add a compound query, for example: `bool`'
    )
  end
end

2. #bool returns the same clause when already boolean

The description mentions removing the re-assignment when #bool is called repeatedly. The "already a boolean query" context checks that Bool.new isn't called again; asserting identity would lock this in:

it 'returns the same boolean clause that was created before' do
  expect(method_call).to be(bool_clause)
end

Nit: the @return tag on the private top_level_clause= setter has no effect, since Ruby ignores a setter's return value when it's called as an assignment. In #bool, clause = if ... else self.top_level_clause = Bool.new end relies on the assignment expression's value, which is correct but easy to misread.

[sergio-bobillier]

Thanks for your review @julian711. I have applied your suggestions.