Ruby-on-rails Rails ActiveSupport：如何断言出现错误？
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Rails ActiveSupport: How to assert that an error is raised?
提问by spilliton
I am wanting to test a function on one of my models that throws specific errors. The function looks something like this:
我想在我的一个模型上测试一个抛出特定错误的函数。该函数看起来像这样：
def merge(release_to_delete)
raise "Can't merge a release with itself!" if( self.id == release_to_delete.id )
raise "Can only merge releases by the same artist" if( self.artist != release_to_delete.artist )
#actual merge code here
end
Now I want to do an assert that when I call this function with a parameter that causes each of those exceptions, that the exceptions actually get thrown. I was looking at ActiveSupport documentation, but I wasn't finding anything promising. Any ideas?
现在我想做一个断言，当我使用导致每个异常的参数调用此函数时，异常实际上会被抛出。我正在查看 ActiveSupport 文档，但没有发现任何有希望的东西。有任何想法吗？
回答by Matt Briggs
So unit testing isn't really in activesupport. Ruby comes with a typical xunit framework in the standard libs (Test::Unit in ruby 1.8.x, MiniTest in ruby 1.9), and the stuff in activesupport just adds some stuff to it.
所以单元测试并不是真的在 activesupport 中。Ruby 在标准库中带有一个典型的 xunit 框架（ruby 1.8.x 中的 Test::Unit，ruby 1.9 中的 MiniTest），而 activesupport 中的东西只是向其中添加了一些东西。
If you are using Test::Unit/MiniTest
如果您使用的是 Test::Unit/MiniTest
assert_raise(Exception) { whatever.merge }
if you are using rspec (unfortunately poorly documented, but way more popular)
如果您使用的是 rspec （不幸的是文档不足，但更受欢迎）
lambda { whatever.merge }.should raise_error
If you want to checkthe raised Exception:
如果要检查凸起Exception：
exception = assert_raises(Exception) { whatever.merge }
assert_equal( "message", exception.message )
回答by shivam
To ensure that no exception is raised (or is successfully handled) do inside your test case:
为确保不会引发（或成功处理）异常，请在您的测试用例中执行以下操作：
assert_nothing_raised RuntimeError do
whatever.merge
end
To check that error is raised do inside your test case:
要检查是否引发了错误，请在您的测试用例中执行以下操作：
assert_raise RuntimeError do
whatever.merge
end
Just a heads up, whatever.mergeis the code that raises the error (or doesn't, depending on the assertion type).
请注意，whatever.merge是引发错误的代码（或不引发错误，取决于断言类型）。
