Merge branch 'js/test-unset-prereq'

Test debugging aid.

* js/test-unset-prereq:
tests: introduce test_unset_prereq, for debugging

diff --combined t/test-lib-functions.sh
index c55ef099c3f174de10a29aaddfb750fa07aa2d8a,dfe99b080f676b85e01fc78da9a5769702be61d3..2b2181dca09089ed36d10ee8f6f67eedda8cf352
--- 1/t/test-lib-functions.sh
--- 2/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@@ -145,28 -145,12 +145,28 @@@ test_pause () 
        "$SHELL_PATH" <&6 >&5 2>&7
  }
  
 -# Wrap git in gdb. Adding this to a command can make it easier to
 -# understand what is going on in a failing test.
 +# Wrap git with a debugger. Adding this to a command can make it easier
 +# to understand what is going on in a failing test.
  #
 -# Example: "debug git checkout master".
 +# Examples:
 +#     debug git checkout master
 +#     debug --debugger=nemiver git $ARGS
 +#     debug -d "valgrind --tool=memcheck --track-origins=yes" git $ARGS
  debug () {
 -       GIT_TEST_GDB=1 "$@" <&6 >&5 2>&7
 +      case "$1" in
 +      -d)
 +              GIT_DEBUGGER="$2" &&
 +              shift 2
 +              ;;
 +      --debugger=*)
 +              GIT_DEBUGGER="${1#*=}" &&
 +              shift 1
 +              ;;
 +      *)
 +              GIT_DEBUGGER=1
 +              ;;
 +      esac &&
 +      GIT_DEBUGGER="${GIT_DEBUGGER}" "$@" <&6 >&5 2>&7
  }
  
  # Call test_commit with the arguments
@@@ -294,8 -278,20 +294,20 @@@ write_script () 
  # The single parameter is the prerequisite tag (a simple word, in all
  # capital letters by convention).
  
+ test_unset_prereq () {
+       ! test_have_prereq "$1" ||
+       satisfied_prereq="${satisfied_prereq% $1 *} ${satisfied_prereq#* $1 }"
+ }
+ 
  test_set_prereq () {
-       satisfied_prereq="$satisfied_prereq$1 "
+       case "$1" in
+       !*)
+               test_unset_prereq "${1#!}"
+               ;;
+       *)
+               satisfied_prereq="$satisfied_prereq$1 "
+               ;;
+       esac
  }
  satisfied_prereq=" "
  lazily_testable_prereq= lazily_tested_prereq=
@@@ -798,8 -794,11 +810,8 @@@ verbose () 
  # otherwise.
  
  test_must_be_empty () {
 -      if ! test -f "$1"
 -      then
 -              echo "'$1' is missing"
 -              return 1
 -      elif test -s "$1"
 +      test_path_is_file "$1" &&
 +      if test -s "$1"
        then
                echo "'$1' is not empty, it contains:"
                cat "$1"