test-lib: allow negation of prerequisites

You can set and test a prerequisite like this:

  test_set_prereq FOO
  test_have_prereq FOO && echo yes

You can negate the test in the shell like this:

  ! test_have_prereq && echo no

However, when you are using the automatic prerequisite
checking in test_expect_*, there is no opportunity to use
the shell negation.  This patch introduces the syntax "!FOO"
to indicate that the test should only run if a prerequisite
is not meant.

One alternative is to set an explicit negative prerequisite,
like:

  if system_has_foo; then
	  test_set_prereq FOO
  else
	  test_set_prereq NO_FOO
  fi

However, this doesn't work for lazy prerequisites, which
associate a single test with a single name. We could teach
the lazy prereq evaluator to set both forms, but the code
change ends up quite similar to this one (because we still
need to convert NO_FOO into FOO to find the correct lazy
script).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/t/t0000-basic.sh b/t/t0000-basic.sh
index 08677df10e9d2a4c87fbe1e5d24eb836b1117e64..562cf41cad7b0532ab4a15625950720c71549742 100755 (executable)
--- a/t/t0000-basic.sh
+++ b/t/t0000-basic.sh
@@ -115,6 +115,38 @@ then
        exit 1
 fi
 
+test_lazy_prereq LAZY_TRUE true
+havetrue=no
+test_expect_success LAZY_TRUE 'test runs if lazy prereq is satisfied' '
+       havetrue=yes
+'
+donthavetrue=yes
+test_expect_success !LAZY_TRUE 'missing lazy prereqs skip tests' '
+       donthavetrue=no
+'
+
+if test "$havetrue$donthavetrue" != yesyes
+then
+       say 'bug in test framework: lazy prerequisites do not work'
+       exit 1
+fi
+
+test_lazy_prereq LAZY_FALSE false
+nothavefalse=no
+test_expect_success !LAZY_FALSE 'negative lazy prereqs checked' '
+       nothavefalse=yes
+'
+havefalse=yes
+test_expect_success LAZY_FALSE 'missing negative lazy prereqs will skip' '
+       havefalse=no
+'
+
+if test "$nothavefalse$havefalse" != yesyes
+then
+       say 'bug in test framework: negative lazy prerequisites do not work'
+       exit 1
+fi
+
 clean=no
 test_expect_success 'tests clean up after themselves' '
        test_when_finished clean=yes

diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 8889ba5104cd3f7c783a179d45816d3a82685ef0..22a4f8fb64a4e8084139fc148e8e7dd4aa73d684 100644 (file)
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -275,6 +275,15 @@ test_have_prereq () {
 
        for prerequisite
        do
+               case "$prerequisite" in
+               !*)
+                       negative_prereq=t
+                       prerequisite=${prerequisite#!}
+                       ;;
+               *)
+                       negative_prereq=
+               esac
+
                case " $lazily_tested_prereq " in
                *" $prerequisite "*)
                        ;;
@@ -294,10 +303,20 @@ test_have_prereq () {
                total_prereq=$(($total_prereq + 1))
                case "$satisfied_prereq" in
                *" $prerequisite "*)
+                       satisfied_this_prereq=t
+                       ;;
+               *)
+                       satisfied_this_prereq=
+               esac
+
+               case "$satisfied_this_prereq,$negative_prereq" in
+               t,|,t)
                        ok_prereq=$(($ok_prereq + 1))
                        ;;
                *)
-                       # Keep a list of missing prerequisites
+                       # Keep a list of missing prerequisites; restore
+                       # the negative marker if necessary.
+                       prerequisite=${negative_prereq:+!}$prerequisite
                        if test -z "$missing_prereq"
                        then
                                missing_prereq=$prerequisite