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      1 # $NetBSD: varmod-order-shuffle.mk,v 1.8 2023/02/26 06:08:06 rillig Exp $
      2 #
      3 # Tests for the :Ox variable modifier, which returns the words of the
      4 # variable, shuffled.
      5 #
      6 # The variable modifier :Ox is available since 2005-06-01.
      7 #
      8 # As of 2020-08-16, make uses random(3) seeded by the current time in seconds.
      9 # This makes the random numbers completely predictable since the only other
     10 # part of make that uses random numbers is the 'randomize-targets' mode, which
     11 # is off by default.
     12 #
     13 # Tags: probabilistic
     14 
     15 WORDS=		one two three four five six seven eight nine ten
     16 
     17 # Note that 1 in every 10! trials two independently generated
     18 # randomized orderings will be the same.  The test framework doesn't
     19 # support checking probabilistic output, so we accept that each of the
     20 # 3 :Ox tests will incorrectly fail with probability 2.756E-7, which
     21 # lets the whole test fail once in 1.209.600 runs, on average.
     22 
     23 # Create two shuffles using the := assignment operator.
     24 shuffled1:=	${WORDS:Ox}
     25 shuffled2:=	${WORDS:Ox}
     26 .if ${shuffled1} == ${shuffled2}
     27 .  error ${shuffled1} == ${shuffled2}
     28 .endif
     29 
     30 # Sorting the list before shuffling it has no effect.
     31 shuffled1:=	${WORDS:O:Ox}
     32 shuffled2:=	${WORDS:O:Ox}
     33 .if ${shuffled1} == ${shuffled2}
     34 .  error ${shuffled1} == ${shuffled2}
     35 .endif
     36 
     37 # Sorting after shuffling must produce the original numbers.
     38 sorted:=	${WORDS:Ox:O}
     39 .if ${sorted} != ${WORDS:O}
     40 .  error ${sorted} != ${WORDS:O}
     41 .endif
     42 
     43 all:
     44