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Fail fast if invocation matches never expectation
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Previously when an invocation matched an expectation which did not allow
invocations (i.e. `Expectation#never` had been called on it), but the
invocation also matched another expectation which did allow invocations,
then the test would not fail with an unexpected invocation error.

This was happening because neither the `if` condition was `true`,
because the "never" expectation was not returned by
`ExpectationList#match_allowing_invocation`, but the other expectation
allowing expectations was returned. Thus `Expectation#invoke` was called
on the latter and `Mock#raise_unexpected_invocation_error` was not
called.

This behaviour was confusing and had led to a number of issues being
raised over the years: #44, #131, #490 & most recently #678. Previously
I had thought this was a symptom of the JMock v1 dispatch behaviour
(which _might_ still be true) and thus would be best addressed by
adopting the JMock v2 dispatch behaviour (#173). However, having
considered this specific scenario involving a "never" expectation, I've
decided to try to fix it with the changes in this commit.

Now a test like this will fail with an unexpected invocation error:

    mock = mock('mock')
    mock.stubs(:method)
    mock.expects(:method).never
    mock.method

    unexpected invocation: #<Mock:mock>.method()
    unsatisfied expectations:
    - expected never, invoked once: #<Mock:mock>.method(any_parameters)
    satisfied expectations:
    - allowed any number of times, invoked never: #<Mock:mock>.method(any_parameters)

Closes #678. Also addresses #490, #131 & #44.
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floehopper committed Nov 13, 2024
1 parent c502471 commit 9ed84cd
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Showing 2 changed files with 19 additions and 1 deletion.
3 changes: 2 additions & 1 deletion lib/mocha/mock.rb
Original file line number Diff line number Diff line change
Expand Up @@ -323,9 +323,10 @@ def handle_method_call(symbol, arguments, block)
invocation = Invocation.new(self, symbol, arguments, block)

matching_expectation_allowing_invocation = all_expectations.match_allowing_invocation(invocation)
matching_expectation_never_allowing_invocation = all_expectations.match_never_allowing_invocation(invocation)
matching_expectation_ignoring_order = all_expectations.match(invocation, ignoring_order: true)

if matching_expectation_allowing_invocation
if matching_expectation_allowing_invocation && !matching_expectation_never_allowing_invocation
matching_expectation_allowing_invocation.invoke(invocation)
elsif matching_expectation_ignoring_order || (!matching_expectation_ignoring_order && !@everything_stubbed)
raise_unexpected_invocation_error(invocation, matching_expectation_ignoring_order)
Expand Down
17 changes: 17 additions & 0 deletions test/acceptance/mocked_methods_dispatch_test.rb
Original file line number Diff line number Diff line change
Expand Up @@ -72,4 +72,21 @@ def test_should_find_latest_expectation_with_range_of_expected_invocation_count_
end
assert_passed(test_result)
end

def test_should_fail_fast_if_invocation_matches_expectation_with_never_cardinality
test_result = run_as_test do
mock = mock('mock')
mock.stubs(:method)
mock.expects(:method).never
mock.method
end
assert_failed(test_result)
assert_equal [
'unexpected invocation: #<Mock:mock>.method()',
'unsatisfied expectations:',
'- expected never, invoked once: #<Mock:mock>.method(any_parameters)',
'satisfied expectations:',
'- allowed any number of times, invoked never: #<Mock:mock>.method(any_parameters)'
], test_result.failure_message_lines
end
end

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