Does verifying the mock is need in minitest

user_6213176 0
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I'm reading the mocking capability of minitest.

require "minitest/autorun"

mock = MiniTest::Mock.new
mock.expect(:use_any_string, true, [String])
mock.use_any_string("foo")
## mock.use_any_string(1)
## MockExpectationError: mocked method :use_any_string called with unexpected arguments [1]


## I do not understand the purpose for this 
mock.verify

So I do not understand the purpose of using mock.verify since the trying to pass any another type(to use_any_string) other than String result in mock expectation error.

So why should one use assert mock.verify then?

minitest
2 Answers

You are right, you cannot set anything else to the configured mock, but if your mock is not called at all, then you can find out with mock.verify. So if your method under test should call the mocked method, you should verify that it was called at all.

user_12878640

You are correct, mock.expect(:use_any_string, true, [String]) will cause the test to fail if the expected call is not made on the mock.

However using mock.verify depends on how you compose your test. In your example you are explicitly calling the method you are testing with mock.use_any_string("foo") so there is no need to also call mock.verify.

You could get into a scenario where you are not making this call explicitly, or are expecting the mock to have had calls made at a certain time. These scenarios would take advantage of mock.verify calls.

(Another note, minitest has recently introduced assert_mock which can be used instead of mock.verify)

user_42506100
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