+test_begin_subtest "Insert message, create invalid subfolder"
+gen_insert_msg
+test_expect_code 1 "notmuch insert --folder=../G --create-folder $gen_msg_filename"
+
+OLDCONFIG=$(notmuch config get new.tags)
+
+test_begin_subtest "Empty tags in new.tags are forbidden"
+notmuch config set new.tags "foo;;bar"
+gen_insert_msg
+output=$(notmuch insert $gen_msg_filename 2>&1)
+test_expect_equal "$output" "Error: tag '' in new.tags: empty tag forbidden"
+
+test_begin_subtest "Tags starting with '-' in new.tags are forbidden"
+notmuch config set new.tags "-foo;bar"
+gen_insert_msg
+output=$(notmuch insert $gen_msg_filename 2>&1)
+test_expect_equal "$output" "Error: tag '-foo' in new.tags: tag starting with '-' forbidden"
+
+test_begin_subtest "Invalid tags set exit code"
+test_expect_code 1 "notmuch insert $gen_msg_filename 2>&1"
+
+notmuch config set new.tags $OLDCONFIG
+
+# DUPLICATE_MESSAGE_ID is not tested here, because it should actually pass.
+
+for code in OUT_OF_MEMORY XAPIAN_EXCEPTION FILE_NOT_EMAIL \
+ READ_ONLY_DATABASE UPGRADE_REQUIRED PATH_ERROR; do
+cat <<EOF > index-file-$code.gdb
+set breakpoint pending on
+set logging file index-file-$code.log
+set logging on
+break notmuch_database_index_file
+commands
+return NOTMUCH_STATUS_$code
+continue
+end
+run
+EOF
+done
+