@@ -15,6 +15,77 @@ module ThoughtBot # :nodoc: end fixtures *all_fixtures end + + # Macro that creates a test asserting a change between the return value + # of an expression that is run before and after the current setup block + # is run. This is similar to Active Support's <tt>assert_difference</tt> + # assertion, but supports more than just numeric values. See also + # should_not_change. + # + # Example: + # + # context "Creating a post" + # setup do + # Post.create + # end + # + # should_change "Post.count", :by => 1 + # end + # + # As shown in this example, the <tt>:by</tt> option expects a numeric + # difference between the before and after values of the expression. You + # may also specify <tt>:from</tt> and <tt>:to</tt> options: + # + # should_change "Post.count", :from => 0, :to => 1 + # should_change "@post.title", :from => "old", :to => "new" + # + # Combinations of <tt>:by</tt>, <tt>:from</tt>, and <tt>:to</tt> are allowed: + # + # should_change "@post.title" # => assert the value changed in some way + # should_change "@post.title" :from => "old" # => assert the value changed to anything other than "old" + # should_change "@post.title" :to => "new" # => assert the value changed from anything other than "new" + def should_change(expression, options = {}) + by, from, to = get_options!([options], :by, :from, :to) + stmt = "change '#{expression}'" + stmt << " from '#{from}'" if from + stmt << " to '#{to}'" if to + stmt << " by #{by}" if by + + expression_eval = lambda { eval(expression) } + before = lambda do + @_before_should_change = expression_eval.bind(self).call + assert_equal from, @_before_should_change, "'#{expression}' was not originally '#{from}'" if from + end + should stmt, :before => before do + old_value = @_before_should_change + new_value = expression_eval.bind(self).call + assert_not_equal old_value, new_value, "'#{expression}' did not change" unless by == 0 + assert_equal to, new_value, "'#{expression}' was not changed to '#{to}'" if to + assert_equal old_value + by, new_value if by + end + end + + # Macro that creates a test asserting no change between the return value + # of an expression that is run before and after the current setup block + # is run. This is the logical opposite of should_change. + # + # Example: + # + # context "Updating a post" + # setup do + # @post.update_attributes(:title => "new") + # end + # + # should_not_change "Post.count" + # end + def should_not_change(expression) + expression_eval = lambda { eval(expression) } + before = lambda { @_before_should_not_change = expression_eval.bind(self).call } + should "not change '#{expression}'", :before => before do + new_value = expression_eval.bind(self).call + assert_equal @_before_should_not_change, new_value, "'#{expression}' changed" + end + end end # Prints a message to stdout, tagged with the name of the calling method. lib/shoulda/general.rb @@ -77,4 +77,35 @@ class HelpersTest < Test::Unit::TestCase # :nodoc: end end end + + context "an array of numbers" do + setup do + @a = [1, 2, 3] + end + + context "after adding another value" do + setup do + @a.push(4) + end + + should_change "@a.length", :by => 1 + should_change "@a.length", :from => 3 + should_change "@a.length", :to => 4 + should_change "@a[0]", :by => 0 + should_not_change "@a[0]" + end + + context "after replacing it with an array of strings" do + setup do + @a = %w(a b c d e f) + end + + should_change "@a.length", :by => 3 + should_change "@a.length", :from => 3, :to => 6, :by => 3 + should_change "@a[0]" + should_change "@a[1]", :from => 2, :to => "b" + should_change "@a[2]", :from => 3 + should_change "@a[3]", :to => "d" + end + end end test/other/helpers_test.rb e6e2f6b906edc4ecd6d7f8a77046216e308d1cf0 Ryan McGeary ryanongit@mcgeary.org http://github.com/rmm5t/shoulda/commit/5f786cbff6cdac99a5c60c36534df84854134c6d 5f786cbff6cdac99a5c60c36534df84854134c6d 2008-07-09T06:53:50-07:00 2008-07-09T06:53:50-07:00 Added new should_change and should_not_change macros; akin to Active Support's assert_difference. 2973919c01bea5be90a959c0798160124766d0e9 Ryan McGeary ryanongit@mcgeary.org