Rails / RSpec：如何测试#initialize方法？
如何使用RSpec指定#initialize行为？ 例如这里：
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
我想设置期望从#initialize方法调用#initialize方法。
对我来说，期望是关于设计合作者之间的对话。 那么，您必须决定 – #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，那么期望就是错误的工具。 而且，由于你有一个种子访问器，你可以这样继续（注意每个例子的一个断言）：
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，如果采摘种子是“种子选择器”角色的一部分，那么模拟在设计种子选择器方面很有价值，dependency injection是分配角色的标准方法。 你可以这样写：
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