Question

我正在尝试使用rspec在Ruby中实现set数据结构。我有一个测试似乎没有通过以下代码：

def add(element)
    if @set_data.include?(element)
        print "This element is already in the set!"
    else
        @set_data += [element]
    end
end

这是对它的测试：

it 'does not add an element if the element is already in the set' do
    set = SetDataStructure.new([1,2,3,4,5])
    set.add(4)
    expect(set).to eq("This element is already in the set!")
end

运行测试的输出：

......这个元素已经在集合中！F。

故障：

1）如果元素已经在集合中，则SetDataStructure不会添加元素失败/错误：期望（set.to_a）.to eq（＆＃34;此元素已经在集合中！＆＃34;）

   expected: "This element is already in the set!"
        got: [1, 2, 3, 4, 5]

   (compared using ==)
 # ./spec/set_data_structure_spec.rb:39:in `block (2 levels) in <top (required)>'

以0.00348秒结束 8个例子，1个失败

失败的例子：

rspec ./spec/set_data_structure_spec.rb:36如果元素已经在集合中，SetDataStructure不会添加元素

我也在我的GitHub上发布了代码。

如果有人能够启发我，我会非常感激！

Answer 1

您的期望不正确。

expect(set).to eq("This element is already in the set!")

您的设置保持不变，您不希望它更改为字符串。这应该是

it 'does not add an element if the element is already in the set' do
  set = SetDataStructure.new([1,2,3,4,5])
  expect { set.add(4) }.to output(/This element is already in the set!/).to_stdout
  # test that set has stayed the  same
  # you probably need to define (override) eq method for SetDataStructure
  expect(set).to eq(SetDataStructure.new([1,2,3,4,5]))
  # alternative is this
  expect(set.set_data).to eq([1,2,3,4,5])
end

Ruby的设置不会打印任何错误，它会默默地不添加要设置的元素。如果您想要这种行为，那么当您添加元素

时，期望set保持不变

it 'does not add an element if the element is already in the set' do
  set = SetDataStructure.new([1,2,3,4,5])
  (1..5).each { |n| set.add(n) }
  expect(set).to eq(SetDataStructure.new([1,2,3,4,5]))
end

Answer 2

如果你真的想要从add方法返回字符串以防元素已经存在，你可以修改你的方法和测试，如下所示：

方法：

def add(element)
  if @set_data.include?(element)
    "This element is already in the set!"     # This will not print the statement, but return it
  else
    @set_data += [element]
  end
end

测试：

it 'does not add an element if the element is already in the set' do
  set = SetDataStructure.new([1,2,3,4,5])
  expect(set.add(4)).to eq("This element is already in the set!")
end

Ruby中

2 个答案: