+# initial segment of file used for several tests below.
+cat <<EOF > comments-and-blanks
+# this is a comment
+
+# next line has leading whitespace
+
+
+EOF
+
+test_begin_subtest 'restoring empty file is not an error'
+notmuch restore < /dev/null 2>OUTPUT.$test_count
+cp /dev/null EXPECTED
+test_expect_equal_file EXPECTED OUTPUT.$test_count
+
+test_begin_subtest 'file of comments and blank lines is not an error'
+notmuch restore --input=comments-and-blanks
+ret_val=$?
+test_expect_equal "$ret_val" "0"
+
+cp comments-and-blanks leading-comments-blanks-batch-tag
+echo "+some_tag -- id:yun1vjwegii.fsf@aiko.keithp.com" \
+ >> leading-comments-blanks-batch-tag
+
+test_begin_subtest 'detect format=batch-tag with leading comments and blanks'
+notmuch restore --input=leading-comments-blanks-batch-tag
+notmuch search --output=tags id:yun1vjwegii.fsf@aiko.keithp.com > OUTPUT.$test_count
+echo "some_tag" > EXPECTED
+test_expect_equal_file EXPECTED OUTPUT.$test_count
+
+cp comments-and-blanks leading-comments-blanks-sup
+echo "yun1vjwegii.fsf@aiko.keithp.com (another_tag)" \
+ >> leading-comments-blanks-sup
+
+test_begin_subtest 'detect format=sup with leading comments and blanks'
+notmuch restore --input=leading-comments-blanks-sup
+notmuch search --output=tags id:yun1vjwegii.fsf@aiko.keithp.com > OUTPUT.$test_count
+echo "another_tag" > EXPECTED
+test_expect_equal_file EXPECTED OUTPUT.$test_count
+