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|
module Concurrent
RSpec.describe Maybe do
context 'construction' do
it 'hides Maybe.new' do
expect {
Maybe.new
}.to raise_error(NoMethodError)
end
context 'Maybe.from' do
it 'raises an exception when no block is given' do
expect {
Maybe.from
}.to raise_error(ArgumentError)
end
it 'passes all arguments to the block' do
expected = [1, 2, 3]
actual = nil
Maybe.from(*expected) do |*args|
actual = args
end
expect(actual).to eq expected
end
it 'creates a Just Maybe on success' do
maybe = Maybe.from{ 42 }
expect(maybe).to be_just
end
it 'sets the value to the block result on success' do
maybe = Maybe.from{ 42 }
expect(maybe.just).to eq 42
end
it 'creates a Nothing Maybe on exception' do
maybe = Maybe.from{ raise StandardError.new }
expect(maybe).to be_nothing
end
it 'sets the reason to the error object on exception' do
ex = StandardError.new
maybe = Maybe.from{ raise ex }
expect(maybe.nothing).to eq ex
end
end
context 'Maybe.just' do
let!(:value) { 42 }
subject { Maybe.just(value) }
it 'creates a new Just Maybe' do
expect(subject).to be_a Maybe
expect(subject).to be_just
end
end
context 'Maybe.nothing' do
let!(:error) { StandardError.new }
subject { Maybe.nothing(error) }
it 'creates a new Nothing Maybe' do
expect(subject).to be_a Maybe
expect(subject).to be_nothing
end
it 'uses the given Error object' do
error = NoMethodError.new
maybe = Maybe.nothing(error)
expect(maybe.nothing).to be error
end
it 'creates a new error object with the given string' do
message = 'What do you get when you multiply six by nine?'
maybe = Maybe.nothing(message)
expect(maybe.nothing).to be_a StandardError
expect(maybe.nothing.message).to eq message
end
it 'creates a new error object when given nothing' do
maybe = Maybe.nothing
expect(maybe.nothing).to be_a StandardError
expect(maybe.nothing.message).to be_empty
end
end
end
context 'when just' do
let!(:value) { 42 }
subject { Maybe.just(value) }
specify '#just? returns true' do
expect(subject).to be_just
end
specify '#fulfilled? returns true' do
expect(subject).to be_fulfilled
end
specify '#nothing? returns false' do
expect(subject).to_not be_nothing
end
specify '#rejected? returns false' do
expect(subject).to_not be_rejected
end
specify '#just returns the value' do
expect(subject.just).to eq value
end
specify '#value returns the value' do
expect(subject.value).to eq value
end
specify '#nothing returns NONE' do
expect(subject.nothing).to be Maybe::NONE
end
specify '#reason returns NONE' do
expect(subject.reason).to be Maybe::NONE
end
end
context 'when nothing' do
let!(:error) { StandardError.new }
subject { Maybe.nothing(error) }
specify '#just? returns false' do
expect(subject).to_not be_just
end
specify '#fulfilled? returns false' do
expect(subject).to_not be_fulfilled
end
specify '#nothing? returns true' do
expect(subject).to be_nothing
end
specify '#rejected? returns true' do
expect(subject).to be_rejected
end
specify '#just returns NONE' do
expect(subject.just).to eq Maybe::NONE
end
specify '#value returns NONE' do
expect(subject.value).to eq Maybe::NONE
end
specify '#nothing returns the raised error' do
expect(subject.nothing).to be error
end
specify '#reason returns the raised error' do
expect(subject.reason).to be error
end
end
context 'comparison' do
let!(:something_big) { Maybe.just(42) }
let!(:something_small) { Maybe.just(1) }
let!(:nothing_big) { Maybe.nothing(StandardError.new) }
let!(:nothing_small) { Maybe.nothing(ArgumentError.new) }
specify 'something is not equal to nothing' do
expect(something_big).to_not eq nothing_big
end
specify 'nothing is equal to nothing' do
expect(nothing_big).to eq nothing_small
end
specify 'something is equal to the same value' do
first = Maybe.just(42)
second = Maybe.just(42)
expect(first).to eq second
end
specify 'something is not equal to a different value' do
expect(something_big).to_not eq something_small
end
specify 'something is greater than a smaller value' do
expect(something_big).to be > something_small
expect(something_big).to be >= something_small
end
specify 'something is less than a bigger value' do
expect(something_small).to be < something_big
expect(something_small).to be <= something_big
end
specify 'nothing is not less than nothing' do
expect(nothing_small).to_not be < nothing_big
end
specify 'nothing is not greater than nothing' do
expect(nothing_big).to_not be > nothing_small
end
end
context '#or' do
it 'returns the value when something' do
maybe = Maybe.just(42)
actual = maybe.or(100)
expect(actual).to eq 42
end
it 'returns the other when nothing' do
maybe = Maybe.nothing
actual = maybe.or(100)
expect(actual).to eq 100
end
end
end
end
|
