class Sus::HaveDuration

def call(assertions, subject)
	assertions.nested(self) do |assertions|
		Expect.new(assertions, measure(subject)).to(@predicate)
	end
end

def initialize(predicate)
	@predicate = predicate
end

def measure(subject)
	start_time = now
	
	subject.call
	
	return now - start_time
end

def now
	::Process.clock_gettime(Process::CLOCK_MONOTONIC)
end

def print(output)
	output.write("have duration ")
	@predicate.print(output)
end