如何使用RSpec指定#initialize行为？例如：
generator.rb
class Generator
attr_accessor :seed
def initialize(seed = nil)
@seed = seed || pick_seed
end
def pick_seed
Time.now.to_i
end
end
generator_spec.rb
require 'generator' describe Generator it "calls 'pick_seed' method unless seed specified" do end end
解决方法
对我来说,期望是在协作者之间设计对话.所以,你必须决定 – #pick_seed是内部实现细节还是协作角色界面的一部分？
如果pick_seed是一个实现细节,期望是工作的错误工具.而且,因为你有一个种子的访问器,你可以这样进行(注意一个例子)
class Generator
attr_accessor :seed
def initialize(seed = nil)
@seed = seed || pick_seed
end
def pick_seed
Time.now.to_i
end
end
describe Generator do
context "creating" do
context "when a seed is specified" do
it "uses that seed" do
seed = 123
generator = Generator.new(seed)
generator.seed.should == seed
end
end
context "when a seed is not specified" do
it "creates its own seed" do
generator = Generator.new
generator.seed.should_not be_nil
end
end
end
end
OTOH,如果选择种子是“种子选择器”角色的一部分,那么嘲讽在设计种子选择器时是有价值的,依赖注入是分配角色的标准方法.你可以写下如下：
class GeneratorWithCollaborator
attr_accessor :seed
def initialize(seed = nil,seed_picker = self)
@seed = seed || seed_picker.pick_seed
end
def pick_seed
Time.now.to_i
end
end
describe GeneratorWithCollaborator do
context "creating" do
context "when a seed is specified" do
it "uses that seed" do
seed = 123
seed_picker = double('seed picker')
seed_picker.should_not_receive(:pick_seed)
generator = GeneratorWithCollaborator.new(seed,seed_picker)
generator.pick_seed
end
end
context "when a seed is not specified" do
it "delegates to its seed picker" do
seed_picker = double('seed picker')
seed_picker.should_receive(:pick_seed)
generator = GeneratorWithCollaborator.new(nil,seed_picker)
end
end
end
end