mocha mock generation with block.rb

# defined in my spec_helper
# requires mocha
# needed because
#  mock() { expects(:foo).with(:bar, anything) }
# does not work. (fails with "Mocha::ExpectationError: unexpected invocation: #<Mock:0x1d8>.anything()")
# Usage:
#  mock_block() do |m|
#    m.expects(:foo).with(:bar, anything)
#  end
def mock_block(&block)
  m = mock()
  yield m if block_given?
  m
end