new_contents: #!/usr/bin/env python
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  __revision__ = "__FILE__ __REVISION__ __DATE__ __DEVELOPER__"
  
  """
  Test that switching Decider() types between MD5 and timestamp-match
  does not cause unnecessary rebuilds.
  """
  
  import TestSCons
  
  test = TestSCons.TestSCons(match=TestSCons.match_re_dotall)
  
  base_sconstruct_contents = """\
  Decider('%s')
  
  def build(env, target, source):
      open(str(target[0]), 'wt').write(open(str(source[0]), 'rt').read())
  B = Builder(action=build)
  env = Environment(BUILDERS = { 'B' : B })
  env.B(target='switch.out', source='switch.in')
  """
  
  def write_SConstruct(test, sig_type):
      contents = base_sconstruct_contents % sig_type
      test.write('SConstruct', contents)
  
  
  # Build first MD5 checksums.
  write_SConstruct(test, 'MD5')
  
  test.write('switch.in', "switch.in\n")
  
  switch_out_switch_in = test.wrap_stdout(r'build\(\["switch.out"\], \["switch.in"\]\)\n')
  
  test.run(arguments='switch.out', stdout=switch_out_switch_in)
  
  test.up_to_date(arguments='switch.out')
  
  
  # Now rebuild with timestamp-match.  Because we always store timestamps,
  # even when making the decision based on MD5 checksums, the build is
  # still up to date.
  write_SConstruct(test, 'timestamp-match')
  
  test.up_to_date(arguments='switch.out')
  
  
  # Now switch back to MD5 checksums.  When we rebuilt with the timestamp,
  # it wiped out the MD5 value (because the point of timestamps is to not
  # open up and checksum the contents), so the file is considered *not*
  # up to date and must be rebuilt to generate a checksum.
  write_SConstruct(test, 'MD5')
  
  test.not_up_to_date(arguments='switch.out')
  
  
  # And just for good measure, make sure that we now rebuild in response
  # to a content change.
  test.write('switch.in', "switch.in 2\n")
  
  test.run(arguments='switch.out', stdout=switch_out_switch_in)
  
  
  test.pass_test()
  
  # Local Variables:
  # tab-width:4
  # indent-tabs-mode:nil
  # End:
  # vim: set expandtab tabstop=4 shiftwidth=4:
  
subject: Add a test of switching back and forth between Decider() values (specifically 'MD5' and 'timestamp-match'), copied from back when this functionality was configured with the SourceSignatures() function.