How to test method alias ruby

Question

How to test if if method has an alias?

Let's say we have

Class Test
  class << self
    def a;end
    alias :b :a
  end
end

so far I came up with idea to write this spec:

it { expect(Test.b).to receive(:a) }

but I believe there is better solution. Any ideas?

Should method aliases even be tested? https://github.com/rspec/rspec-core/issues/1962 — chemturion, Jan 09 '19 at 20:53
@chemturion years after asking this question, years of writing countless tests in RSpec I can definitely say that you shouldn't :) — Filip Bartuzi, Jan 15 '19 at 08:55

score 18 · Accepted Answer · answered Sep 17 '14 at 06:26

18

You can use Object#method.

Test.method(:b) == Test.method(:a)

answered Sep 17 '14 at 06:26

oldergod

15,033
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2

To use this on a `Test` instance method: `Test.new.method(:b) == Test.new.method(:a)` – Anthony To Jan 29 '18 at 23:49

score 9 · Answer 2 · answered May 06 '17 at 12:25

9

You can use:

expect(obj.method(:method)).to eq(obj.method(:alias))

answered May 06 '17 at 12:25

Arnold Roa

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Jeff Manian · Answer 3 · 2018-04-11T16:53:44.903

oldergod's answer works in most scenarios:

Test.method(:b) == Test.method(:a)

Unfortunately it doesn't work in Ruby 2.3+ when the two methods have different owners (e.g. when the method is defined in a module, and the alias is defined in a class that includes the module). This is because the behavior of Method#== changed in Ruby 2.3:

If owners of methods are different, the behavior of super is different in the methods, so Method#== should not return true for the methods.

If you find yourself in this situation, where you want to test that two methods are aliases of each other but they have different owners, you can use Method#original_name or Method#source_location instead:

Test.method(:b).original_name == Test.method(:a).original_name
Test.method(:b).source_location == Test.method(:a).source_location

I found out that it doesn't work at all in Ruby 2.7. – andrykonchin Jul 18 '20 at 21:37 — andrykonchin, Jul 18 '20 at 21:37

score -4 · Answer 4 · answered Sep 17 '14 at 06:26

-4

You can set a result to your function to check if result is same.

def a
  return 'test string'
end

then it { expect(Test.b).to eq(Test.a) }

is it ok?

answered Sep 17 '14 at 06:26

dddd1919

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5
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2

Same result doesn't mean it's an alias. – Filip Bartuzi Sep 17 '14 at 06:30

How to test method alias ruby

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