[PATCH v3 10/9] difftool: do not allow mix of '--prompt' with '--no-prompt'

[Tim Henigan <tim.henigan@gmail.com>]

When difftool was changed to use Getopt::Long, it changed the way that
the '--prompt' and '--no-prompt' options are handled. Prior to the change,
if both options were given, then the last option was used.  After the
change, if both were given, then '--prompt' was always used.

This commit teaches difftool to exit with an error if both options are
given at the command line. t7800 was updated to match.

Signed-off-by: Tim Henigan <tim.henigan@gmail.com>
---
 git-difftool.perl   |    6 +++++-
 t/t7800-difftool.sh |   16 +++++-----------
 2 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/git-difftool.perl b/git-difftool.perl
index 9f0f9a9..9629811 100755
--- a/git-difftool.perl
+++ b/git-difftool.perl
@@ -202,7 +202,11 @@ if (defined($dirdiff)) {
 		chmod(stat("$b/$_")->mode, "$workdir/$_") or die $!;
 	}
 } else {
-	if (defined($prompt)) {
+	if (defined($prompt) and defined($no_prompt)) {
+		print("Cannot command '--prompt' and '--no-prompt' at the same time.\n");
+		usage(1);
+	}
+	elsif (defined($prompt)) {
 		$ENV{GIT_DIFFTOOL_PROMPT} = 'true';
 	}
 	elsif (defined($no_prompt)) {
diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
index 4fb4c93..dc181cf 100755
--- a/t/t7800-difftool.sh
+++ b/t/t7800-difftool.sh
@@ -202,17 +202,11 @@ test_expect_success PERL 'difftool.prompt can overridden with --prompt' '
 	restore_test_defaults
 '
 
-# Test that the last flag passed on the command-line wins
-test_expect_success PERL 'difftool last flag wins' '
-	diff=$(git difftool --prompt --no-prompt branch) &&
-	test "$diff" = "branch" &&
-
-	restore_test_defaults &&
-
-	prompt=$(echo | git difftool --no-prompt --prompt branch | tail -1) &&
-	prompt_given "$prompt" &&
-
-	restore_test_defaults
+# Test that an error is given when both --prompt and --no-prompt are
+# commanded
+test_expect_success PERL '--prompt / --no-prompt conflict' '
+	test_must_fail git difftool --prompt --no-prompt branch &&
+	test_must_fail git difftool --no-prompt --prompt branch
 '
 
 # git-difftool falls back to git-mergetool config variables
-- 
1.7.10.rc1.39.g6e141f