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require 'test/unit/assertions'
module Test
module Unit
#--
# FIXME: no Proc#binding in Ruby 2, must change this API
#++
module Assertions
# Test numeric difference between the return value of an expression as a result of what is evaluated
# in the yielded block.
#
# assert_difference 'Article.count' do
# post :create, :article => {...}
# end
#
# An arbitrary expression is passed in and evaluated.
#
# assert_difference 'assigns(:article).comments(:reload).size' do
# post :create, :comment => {...}
# end
#
# An arbitrary positive or negative difference can be specified. The default is +1.
#
# assert_difference 'Article.count', -1 do
# post :delete, :id => ...
# end
#
# An array of expressions can also be passed in and evaluated.
#
# assert_difference [ 'Article.count', 'Post.count' ], +2 do
# post :create, :article => {...}
# end
#
# A error message can be specified.
#
# assert_difference 'Article.count', -1, "An Article should be destroyed" do
# post :delete, :id => ...
# end
def assert_difference(expressions, difference = 1, message = nil, &block)
expression_evaluations = Array(expressions).map do |expression|
lambda do
eval(expression, block.__send__(:binding))
end
end
original_values = expression_evaluations.inject([]) { |memo, expression| memo << expression.call }
yield
expression_evaluations.each_with_index do |expression, i|
assert_equal original_values[i] + difference, expression.call, message
end
end
# Assertion that the numeric result of evaluating an expression is not changed before and after
# invoking the passed in block.
#
# assert_no_difference 'Article.count' do
# post :create, :article => invalid_attributes
# end
#
# A error message can be specified.
#
# assert_no_difference 'Article.count', "An Article should not be destroyed" do
# post :create, :article => invalid_attributes
# end
def assert_no_difference(expressions, message = nil, &block)
assert_difference expressions, 0, message, &block
end
end
end
end
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