require 'spec_helper' describe 'Just()' do include ConvertableNull::Conversions specify 'passes non-nullish values through' do expect(Just(false)).to be(false) str = 'hello' expect(Just(str)).to be(str) end specify 'rejects nullish values' do expect { Just(nil) }.to raise_error(ArgumentError) expect { Just('') }.to raise_error(ArgumentError) expect { Just(ConvertableNull.get) }.to raise_error(ArgumentError) end it 'also works with blocks' do expect { Just { nil }.class }.to raise_error(ArgumentError) expect(Just { 'foo' }).to eq('foo') end end