Module: Ayudante::AssertChanges

Included in:
Test::Unit::TestCase
Defined in:
lib/ayudante/assert_changes.rb

Instance Method Summary collapse

Instance Method Details

#assert_changes(transitions, &block) ⇒ Object

Assertion that a specific state changes during invocation of the passed in block.

i = 'simple'
assert_changes 'i' => 'whacky' do
   i = 'whacky'
end

This can be read “assert i changes to wacky”. Function will verify both the precondition (i is NOT wacky), and the post-condition.

This means i becomes nil during the block (and therefore non-nil

beforehand):
 assert_changes 'i' => nil do ...

If you want to specify a specific transition, you can do so by providing an array:

assert_changes 'i' => ['simple','whacky'] do

To specify that there should be no changes, use the symbol :no_change.

assert_changes 'i' => :no_change do

Finally, multiple assertions can be passed for larger sets of state changes:

i, j = 1,2
assert_changes 'i' => [1, 2], 'j' => [2, 1] do
   Mixer.mix(i,j)
end



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# File 'lib/ayudante/assert_changes.rb', line 37

def assert_changes(transitions, &block)
  transitions = [transitions] if transitions.class==String
  if transitions.class == Array
    h = Hash.new
    transitions.each {|i| h[i] = :any_change}
    transitions = h
  end
  transitions.each  do |expression, value|
    result = eval(expression, block.__send__(:binding))
    if value == :no_change
      transitions[expression] = [result, result]
    elsif value == :any_change
      transitions[expression] = [result, :any_change]
    elsif value.nil?
      assert_not_nil(result, "Precondition not met")
    else
      pre_value = (value.class == Array) ? value[0] : !value
      assert_equal pre_value, result, "Precondition not met: " + expression
    end
  end
  yield
  transitions.each  do |expression, value|
    final_value = (value.class == Array) ? value[1] : value
    new_value = eval(expression, block.__send__(:binding))
    if final_value == :any_change
      assert value[0] != new_value, "Any change failed for " + expression
    else
      assert_equal final_value, new_value, "Change failed for " + expression
    end
  end
end

#assert_no_changes(transitions, &block) ⇒ Object 



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# File 'lib/ayudante/assert_changes.rb', line 70

def assert_no_changes(transitions, &block)
  if String === transitions
    assert_changes(transitions=>:no_change, &block)
  elsif Array === transitions
    assert_changes(transitions.inject({}) { |map, exp| map.merge(exp => :no_change) }, &block)
  else  # map
    map = {}
    transitions.each {|k, v| map[k]=[v, v]}
    assert_changes(map, &block)
  end
end