From 16f24cd10ffca6be49e394b9404e9564a94aeeda Mon Sep 17 00:00:00 2001 From: Genadi Samokovarov Date: Mon, 13 Jun 2016 23:28:05 +0300 Subject: [PATCH] Introduce `assert_changes` and `assert_no_changes` Those are assertions that I really do miss from the standard `ActiveSupport::TestCase`. Think of those as a more general version of `assert_difference` and `assert_no_difference` (those can be implemented by assert_changes, should this change be accepted). Why do we need those? They are useful when you want to check a side-effect of an operation. `assert_difference` do cover a really common case, but we `assert_changes` gives us more control. Having a global error flag? You can test it easily with `assert_changes`. In fact, you can be really specific about the initial state and the terminal one. ```ruby error = Error.new(:bad) assert_changes -> { Error.current }, from: nil, to: error do expected_bad_operation end ``` `assert_changes` follows `assert_difference` and a string can be given for evaluation as well. ```ruby error = Error.new(:bad) assert_changes 'Error.current', from: nil, to: error do expected_bad_operation end ``` Check out the test cases if you wanna see more examples. :beers: --- activesupport/CHANGELOG.md | 50 +++++++-- .../lib/active_support/testing/assertions.rb | 89 +++++++++++++++ activesupport/test/test_case_test.rb | 106 ++++++++++++++++++ 3 files changed, 236 insertions(+), 9 deletions(-) diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md index 6103857a41..3749dda9fc 100644 --- a/activesupport/CHANGELOG.md +++ b/activesupport/CHANGELOG.md @@ -1,3 +1,36 @@ +* Introduce `assert_changes` and `assert_no_changes`. + + `assert_changes` is a more general `assert_difference` that works with any + value. + + assert_changes 'Error.current', from: nil, to: 'ERR' do + expected_bad_operation + end + + Can be called with strings, to be evaluated in the binding (context) of + the block given to the assertion, or a lambda. + + assert_changes -> { Error.current }, from: nil, to: 'ERR' do + expected_bad_operation + end + + The `from` and `to` arguments are compared with the case operator (`===`). + + assert_changes 'Error.current', from: nil, to: Error do + expected_bad_operation + end + + This is pretty useful, if you need to loosely compare a value. For example, + you need to test a token has been generated and it has that many random + characters. + + user = User.start_registration + assert_changes 'user.token', to: /\w{32}/ do + user.finish_registration + end + + *Genadi Samokovarov* + * Add `:fallback_string` option to `Array#to_sentence`. If an empty array calls the function and a fallback string option is set then it returns the fallback string other than an empty string. @@ -15,14 +48,14 @@ * `travel/travel_to` travel time helpers, now raise on nested calls, as this can lead to confusing time stubbing. - + Instead of: - + travel_to 2.days.from_now do # 2 days from today travel_to 3.days.from_now do # 5 days from today - end + end end preferred way to achieve above is: @@ -30,13 +63,12 @@ travel 2.days do # 2 days from today end - - travel 5.days do - # 5 days from today - end - + + travel 5.days do + # 5 days from today + end + *Vipul A M* - * Support parsing JSON time in ISO8601 local time strings in `ActiveSupport::JSON.decode` when `parse_json_times` is enabled. diff --git a/activesupport/lib/active_support/testing/assertions.rb b/activesupport/lib/active_support/testing/assertions.rb index ad83638572..7770aa8006 100644 --- a/activesupport/lib/active_support/testing/assertions.rb +++ b/activesupport/lib/active_support/testing/assertions.rb @@ -1,6 +1,8 @@ module ActiveSupport module Testing module Assertions + UNTRACKED = Object.new # :nodoc: + # Asserts that an expression is not truthy. Passes if object is # +nil+ or +false+. "Truthy" means "considered true in a conditional" # like if foo. @@ -92,6 +94,93 @@ def assert_difference(expression, difference = 1, message = nil, &block) def assert_no_difference(expression, message = nil, &block) assert_difference expression, 0, message, &block end + + # Assertion that the result of evaluating an expression is changed before + # and after invoking the passed in block. + # + # assert_changes 'Status.all_good?' do + # post :create, params: { status: { ok: false } } + # end + # + # You can pass the block as a string to be evaluated in the context of + # the block. A lambda can be passed for the block as well. + # + # assert_changes -> { Status.all_good? } do + # post :create, params: { status: { ok: false } } + # end + # + # The assertion is useful to test side effects. The passed block can be + # anything that can be converted to string with #to_s. + # + # assert_changes :@object do + # @object = 42 + # end + # + # The keyword arguments :from and :to can be given to specify the + # expected initial value and the expected value after the block was + # executed. + # + # assert_changes :@object, from: nil, to: :foo do + # @object = :foo + # end + # + # An error message can be specified. + # + # assert_changes -> { Status.all_good? }, 'Expected the status to be bad' do + # post :create, params: { status: { incident: true } } + # end + def assert_changes(expression, message = nil, from: UNTRACKED, to: UNTRACKED, &block) + exp = expression.respond_to?(:call) ? expression : -> { eval(expression.to_s, block.binding) } + + before = exp.call + retval = yield + + unless from == UNTRACKED + error = "#{expression.inspect} isn't #{from}" + error = "#{message}.\n#{error}" if message + assert from === before, error + end + + after = exp.call + + if to == UNTRACKED + error = "#{expression.inspect} didn't changed" + error = "#{message}.\n#{error}" if message + assert_not_equal before, after, error + else + message = "#{expression.inspect} didn't change to #{to}" + error = "#{message}.\n#{error}" if message + assert to === after, error + end + + retval + end + + # Assertion that the result of evaluating an expression is changed before + # and after invoking the passed in block. + # + # assert_no_changes 'Status.all_good?' do + # post :create, params: { status: { ok: true } } + # end + # + # An error message can be specified. + # + # assert_no_changes -> { Status.all_good? }, 'Expected the status to be good' do + # post :create, params: { status: { ok: false } } + # end + def assert_no_changes(expression, message = nil, &block) + exp = expression.respond_to?(:call) ? expression : -> { eval(expression.to_s, block.binding) } + + before = exp.call + retval = yield + after = exp.call + + error = "#{expression.inspect} did change to #{after}" + error = "#{message}.\n#{error}" if message + assert_equal before, after, error + + retval + end end end end diff --git a/activesupport/test/test_case_test.rb b/activesupport/test/test_case_test.rb index 18228a2ac5..772c3cfca7 100644 --- a/activesupport/test/test_case_test.rb +++ b/activesupport/test/test_case_test.rb @@ -111,6 +111,112 @@ def test_array_of_expressions_identify_failure_when_message_provided end end end + + def test_assert_changes_pass + assert_changes '@object.num' do + @object.increment + end + end + + def test_assert_changes_pass_with_lambda + assert_changes -> { @object.num } do + @object.increment + end + end + + def test_assert_changes_with_from_option + assert_changes '@object.num', from: 0 do + @object.increment + end + end + + def test_assert_changes_with_from_option_with_wrong_value + assert_raises Minitest::Assertion do + assert_changes '@object.num', from: -1 do + @object.increment + end + end + end + + def test_assert_changes_with_to_option + assert_changes '@object.num', to: 1 do + @object.increment + end + end + + def test_assert_changes_with_wrong_to_option + assert_raises Minitest::Assertion do + assert_changes '@object.num', to: 2 do + @object.increment + end + end + end + + def test_assert_changes_with_from_option_and_to_option + assert_changes '@object.num', from: 0, to: 1 do + @object.increment + end + end + + def test_assert_changes_with_from_and_to_options_and_wrong_to_value + assert_raises Minitest::Assertion do + assert_changes '@object.num', from: 0, to: 2 do + @object.increment + end + end + end + + def test_assert_changes_works_with_any_object + retval = silence_warnings do + assert_changes :@new_object, from: nil, to: 42 do + @new_object = 42 + end + end + + assert_equal 42, retval + end + + def test_assert_changes_works_with_nil + oldval = @object + + retval = assert_changes :@object, from: oldval, to: nil do + @object = nil + end + + assert_nil retval + end + + def test_assert_changes_with_to_and_case_operator + token = nil + + assert_changes 'token', to: /\w{32}/ do + token = SecureRandom.hex + end + end + + def test_assert_changes_with_to_and_from_and_case_operator + token = SecureRandom.hex + + assert_changes 'token', from: /\w{32}/, to: /\w{32}/ do + token = SecureRandom.hex + end + end + + def test_assert_no_changes_pass + assert_no_changes '@object.num' do + # ... + end + end + + def test_assert_no_changes_with_message + error = assert_raises Minitest::Assertion do + assert_no_changes '@object.num', '@object.num should not change' do + @object.increment + end + end + + assert_equal "@object.num should not change.\n\"@object.num\" did change to 1.\nExpected: 0\n Actual: 1", error.message + end end class AlsoDoingNothingTest < ActiveSupport::TestCase -- GitLab