ruby 如何设置方法测试中使用的私有实例变量？
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How to set private instance variable used within a method test?
提问by Torbj?rn
Given a class with a couple of instance variables and some methods. Some instance variables are set accessible via attr_readerand attr_accessor. Thus the others are private.
Some of the private instance variables get set within one of the instance methods and read/utilized within another method.
给定一个带有几个实例变量和一些方法的类。一些实例变量设置为可通过attr_reader和访问attr_accessor。因此其他人是私人的。
一些私有实例变量在一个实例方法中设置并在另一个方法中读取/使用。
For testing I'm using RSpec. As I'm still new to Ruby and want to get all things right, I defined my tests being rather fine-grained. Thus I've got one describeblock for each instance method, which themselves are partitioned into a subset of contexts and its. General environmental preconditions are defined with before.
为了测试，我使用 RSpec。由于我还是 Ruby 的新手并且想要把所有事情都做对，所以我将我的测试定义为相当细粒度的。因此describe，每个实例方法都有一个块，它们本身被划分为contexts 和its的子集。一般环境先决条件定义为before。
However, when testing one of the methods, which is utilizing but not setting one of the private variables, I need to call the other method, which is setting this variable. This seems rather overweight and not modular for me.
但是，在测试其中一种方法（正在使用但未设置其中一个私有变量）时，我需要调用另一种方法，即设置此变量的方法。这对我来说似乎相当超重，而不是模块化。
Is there a way of forcing a private instance variable to a certain value. Similar to "ripping out" the value of a private instance variable with Object::instance_eval(:var).
有没有办法将私有实例变量强制为某个值。类似于“撕掉”私有实例变量的值Object::instance_eval(:var)。
回答by Aliaksei Kliuchnikau
As you answered in your question the easiest way to set instance variable is with instance_evalmethod:
正如您在问题中回答的那样，设置实例变量的最简单方法是使用instance_eval方法：
obj.instance_eval('@a = 1')
Another way is to use instance_variable_set:
另一种方法是使用 instance_variable_set：
obj.instance_variable_set(:@a, 1)
But I would not recommend to do this in your specs. Specs are all about testing behavior of an object and testing behaviour by breaking class encapsulation with instance_evalwill make your tests more fragile and implementation dependent.
但我不建议在您的规范中执行此操作。规范都是关于测试对象的行为，并且通过破坏类封装来测试行为instance_eval将使您的测试更加脆弱并依赖于实现。
Alternative approach to object state isolation is to stub accessor methods:
对象状态隔离的另一种方法是存根访问器方法：
class UnderTest
attr_accessor :a
def test_this
do_something if a == 1
end
end
#in your test
under_test = UnderTest.new
under_test.stub(:a).and_return(1)
回答by robbrit
Use instance_variable_set:
使用instance_variable_set：
class SomeClass
attr_reader :hello
def initialize
@hello = 5
end
# ...
end
a = SomeClass.new
a.hello # => 5
a.instance_variable_set("@hello", 7)
a.hello # => 7
回答by Chris
I just solved it by creating a child and adding an accessor:
我只是通过创建一个子项并添加一个访问器来解决它：
class HasSecrets
@muahaha
end
class TestMe < HasSecrets
attr_accessor(:muahaha)
end
def test_stuff
pwned = TestMe.new()
pwned.muahaha = 'calc.exe'
end
