bisect: verify that a bogus option won't try to start a bisection

We do not want `git bisect --bogus-option` to start a bisection. To
verify that, we look for the tell-tale error message `You need to start
by "git bisect start"` and fail if it was found.

Signed-off-by: Johannes Schindelin <[email protected]>
Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: dscho

t/t6030-bisect-porcelain.sh

@@ -1058,6 +1058,16 @@ test_expect_success 'bisect start with one term1 and term2' '
 	git bisect reset
 '
 
+test_expect_success 'bogus command does not start bisect' '
+	git bisect reset &&
+	test_must_fail git bisect --bisect-terms 1 2 2>out &&
+	! grep "You need to start" out &&
+	test_must_fail git bisect --bisect-terms 2>out &&
+	! grep "You need to start" out &&
+	grep "git bisect.*visualize" out &&
+	git bisect reset
+'
+
 test_expect_success 'bisect replay with term1 and term2' '
 	git bisect replay log_to_replay.txt >bisect_result &&
 	grep "$HASH2 is the first term1 commit" bisect_result &&