Ruby name of method that not called from another method by using dot -

i'm learning ruby using tdd (test driven development). in rspec code, see:

it "return sum of 2 different arugments"       calc = calculator.new       expect(calc.add(1,2)).to eq(3)  end 

often, in other languages, last command written eq (expect(calc(1,2)), 3) or expect(calc.add(1,2)).eq(3).

but in example, there nothing connecting first phrase expect(calc.add(1,2)) , second phrase eq(3).

so in ruby, name of grammar?

it pair of parentheses around arguments can omitted.

expect(calc.add(1, 2)).to eq(3) 

is syntax sugared form of:

expect(calc.add(1, 2)).to(eq(3)) 

that is, eq(3) argument of method to.

according @digitalross, seems called poetry mode.