Error on expects.with with empty hash argument

[josesei]

How to reproduce:

minitest (5.24.1)
mocha (2.4.2)
rails (6.1.7.8)

Ruby 3.3.0

require "test_helper"

class MyKlass
  def self.method_accepting_hash(h)
    "whatever"
  end
end

class MochaErrorTest < ActiveSupport::TestCase
  hash_with_value1 = {"key" => "value"}
  hash_with_value2 = {"key2" => "value2"}
  empty_hash = {}

  test "mocha success, hash with values" do
    MyKlass.expects(:method_accepting_hash).once.with(hash_with_value1).returns("whatever")
    MyKlass.expects(:method_accepting_hash).once.with(hash_with_value2).returns("whatever")
    MyKlass.method_accepting_hash(hash_with_value1)
    MyKlass.method_accepting_hash(hash_with_value2)
  end
  
  test "mocha success, empty hashes" do
    MyKlass.expects(:method_accepting_hash).once.with(empty_hash).returns("whatever")
    MyKlass.expects(:method_accepting_hash).once.with(empty_hash).returns("whatever")
    MyKlass.method_accepting_hash(empty_hash)
    MyKlass.method_accepting_hash(empty_hash)
  end

  test "mocha success first empty hash, then hash with values" do
    MyKlass.expects(:method_accepting_hash).once.with(empty_hash).returns("whatever")
    MyKlass.expects(:method_accepting_hash).once.with(hash_with_value1).returns("whatever")
    MyKlass.method_accepting_hash(empty_hash)
    MyKlass.method_accepting_hash(hash_with_value1)
  end
  
  test "mocha error first hash with values, then empty hash, weird error message?" do
    MyKlass.expects(:method_accepting_hash).once.with(hash_with_value1).returns("whatever")
    MyKlass.expects(:method_accepting_hash).once.with(empty_hash).returns("whatever")
    MyKlass.method_accepting_hash(hash_with_value1)
    MyKlass.method_accepting_hash(empty_hash)
  end
end

Failure:

Minitest::Assertion: unexpected invocation: MyKlass.method_accepting_hash({})
unsatisfied expectations:

• expected exactly once, invoked twice: MyKlass.method_accepting_hash({})
• expected exactly once, invoked never: MyKlass.method_accepting_hash({"key" => "value"})

test/support/mocha_error_test.rb:31:in `block in class:MochaErrorTest'

[josesei]

workaround is to use block matcher

[josesei]

@floehopper just in case

module ParameterMatchers
    # @private
    class PositionalOrKeywordHash < Base
      def matches?(available_parameters)
        parameter, is_last_parameter = extract_parameter(available_parameters)

        # return false unless HasEntries.new(@value).matches?([parameter]) <---- commenting this line makes the tests pass

Possibly you need that for something else, but I'd love to get that fixed

[floehopper]

@josesei Thanks for reporting this. I had independently come to the same conclusion as you as to where the problem lies. I've managed to write a couple of failing unit tests in #660 which reproduce the issue. That line of code is needed to handle nested matchers with keyword arguments (see test below), but clearly the implentation isn't quite right. My head is pretty scrambled right now, but I'll try to get it fixed as soon as I can.

mocha/test/unit/parameter_matchers/positional_or_keyword_hash_test.rb

Lines 38 to 41 in e62fa61

	def test_should_match_keyword_args_with_matchers_using_keyword_args
	matcher = Hash.ruby2_keywords_hash({ key_1: is_a(String), key_2: is_a(Integer) }).to_matcher(top_level: true) # rubocop:disable Style/BracesAroundHashParameters
	assert matcher.matches?([Hash.ruby2_keywords_hash({ key_1: 'foo', key_2: 2 })]) # rubocop:disable Style/BracesAroundHashParameters
	end

[josesei]

sounds good, thx!

[floehopper]

@josesei Quick question - were these tests working with earlier versions of Mocha (e.g. v2.2.0)?

Actually - ignore that!

[floehopper]

@josesei I've got some tidying up to do and some double-checking I haven't broken anything else, but I think the changes in the fix-regression-in-matching-hash-parameter branch should fix your problem. If you get the chance, I'd really appreciate it if you could see if it does fix the problem.

[josesei]

yep, it does work now! appreciate the effort!

it worked for me for ruby 2.6 and rails 5, mocha version mocha (1.13.0)

I guess it has to do with the keyword params compat thingy, but I'm sure you have it

[floehopper]

@josesei Thanks for testing. The problem was something I accidentally introduced in v2.3.0 (specifically f94e250) as a fix for #647 where a Hash parameter passed into Expectation#with was implicitly wrapped in a call to #has_entries. The latter does not require an exact match - only the specified entries have to match. The fix is to ensure that all entries match and that there are no extra entries. I hope to release the fix later today.

[josesei]

Makes sense, thanks for the insights and all your work!

[floehopper]

This fix has been released in v2.4.3.