git-send-email: improve --validate error output

Improve the output we emit on --validate error to:

 * Say "FILE:LINE" instead of "FILE: LINE", to match "grep -n",
   compiler error messages etc.

 * Don't say "patch contains a" after just mentioning the filename,
   just leave it at "FILE:LINE: is longer than[...]. The "contains a"
   sounded like we were talking about the file in general, when we're
   actually checking it line-by-line.

 * Don't just say "rejected by sendemail-validate hook", but combine
   that with the system_or_msg() output to say what exit code the hook
   died with.

I had an aborted attempt to make the line length checker note all
lines that were longer than the limit. I didn't think that was worth
the effort, but I've left in the testing change to check that we die
as soon as we spot the first long line.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-send-email.perl

@@ -219,8 +219,8 @@ sub system_or_msg {
 	my $exit_code = $? >> 8;
 	return unless $signalled or $exit_code;
 
-	return sprintf(__("failed to run command %s, died with code %d"),
-		       "@$args", $exit_code);
+	return sprintf(__("fatal: command '%s' died with exit code %d"),
+		       $args->[0], $exit_code);
 }
 
 sub system_or_die {
@@ -1964,7 +1964,8 @@ sub validate_patch {
 		}
 		if ($hook_error) {
 			die sprintf(__("fatal: %s: rejected by sendemail-validate hook\n" .
-				       "warning: no patches were sent\n"), $fn);
+				       "%s\n" .
+				       "warning: no patches were sent\n"), $fn, $hook_error);
 		}
 	}
 
@@ -1975,9 +1976,8 @@ sub validate_patch {
 			or die sprintf(__("unable to open %s: %s\n"), $fn, $!);
 		while (my $line = <$fh>) {
 			if (length($line) > 998) {
-				die sprintf(__("fatal: %s: %d: patch contains a line longer than 998 characters\n" .
-					       "warning: no patches were sent\n"),
-					    $fn, $.);
+				die sprintf(__("fatal: %s:%d is longer than 998 characters\n" .
+					       "warning: no patches were sent\n"), $fn, $.);
 			}
 		}
 	}

t/t9001-send-email.sh

@@ -415,7 +415,11 @@ test_expect_success $PREREQ 'reject long lines' '
 	z512=$z64$z64$z64$z64$z64$z64$z64$z64 &&
 	clean_fake_sendmail &&
 	cp $patches longline.patch &&
-	echo $z512$z512 >>longline.patch &&
+	cat >>longline.patch <<-EOF &&
+	$z512$z512
+	not a long line
+	$z512$z512
+	EOF
 	test_must_fail git send-email \
 		--from="Example <nobody@example.com>" \
 		--to=nobody@example.com \
@@ -424,7 +428,7 @@ test_expect_success $PREREQ 'reject long lines' '
 		$patches longline.patch \
 		2>actual &&
 	cat >expect <<-\EOF &&
-	fatal: longline.patch: 35: patch contains a line longer than 998 characters
+	fatal: longline.patch:35 is longer than 998 characters
 	warning: no patches were sent
 	EOF
 	test_cmp expect actual
@@ -533,15 +537,17 @@ test_expect_success $PREREQ "--validate respects relative core.hooksPath path" '
 		--validate \
 		longline.patch 2>actual &&
 	test_path_is_file my-hooks.ran &&
-	cat >expect <<-\EOF &&
+	cat >expect <<-EOF &&
 	fatal: longline.patch: rejected by sendemail-validate hook
+	fatal: command '"'"'$(pwd)/my-hooks/sendemail-validate'"'"' died with exit code 1
 	warning: no patches were sent
 	EOF
 	test_cmp expect actual
 '
 
 test_expect_success $PREREQ "--validate respects absolute core.hooksPath path" '
-	test_config core.hooksPath "$(pwd)/my-hooks" &&
+	hooks_path="$(pwd)/my-hooks" &&
+	test_config core.hooksPath "$hooks_path" &&
 	test_when_finished "rm my-hooks.ran" &&
 	test_must_fail git send-email \
 		--from="Example <nobody@example.com>" \
@@ -550,8 +556,9 @@ test_expect_success $PREREQ "--validate respects absolute core.hooksPath path" '
 		--validate \
 		longline.patch 2>actual &&
 	test_path_is_file my-hooks.ran &&
-	cat >expect <<-\EOF &&
+	cat >expect <<-EOF &&
 	fatal: longline.patch: rejected by sendemail-validate hook
+	fatal: command '"'"'$hooks_path/sendemail-validate'"'"' died with exit code 1
 	warning: no patches were sent
 	EOF
 	test_cmp expect actual