$ vendor/bin/phpunit --filter '::test_email_to_user_attachment()'
Moodle 3.10rc1 (Build: 20201105), 150f3e0736397924a645765f988d0f49ebb943f8
Php: 7.2.34, mariadb: 10.2.33, OS: Darwin 19.6.0 x86_64
PHPUnit 8.5.8 by Sebastian Bergmann and contributors.

.....F..                                                            8 / 8 (100%)

Time: 12.8 seconds, Memory: 486.50 MB

There was 1 failure:

1) core_moodlelib_testcase::test_email_to_user_attachment with data set "localrequestdir" ('/var/folders/3b/4q5trjyj3h99k...estdir')
Failed asserting that 'This is a multi-part message in MIME format.\n
--b1_o4Ipxc0DJkoLQ73EKd2fDybZAxtXBVfejDPTLZSEcd0\n
Content-Type: text/plain; charset=UTF-8\n
Content-Transfer-Encoding: quoted-printable\n
\n
=0ATest attachment path=0A\n
--b1_o4Ipxc0DJkoLQ73EKd2fDybZAxtXBVfejDPTLZSEcd0\n
Content-Type: text/html; charset=UTF-8\n
Content-Transfer-Encoding: quoted-printable\n
\n
Test attachment path\n
\n
--b1_o4Ipxc0DJkoLQ73EKd2fDybZAxtXBVfejDPTLZSEcd0--\n
' contains "Content-Type: text/plain; name="hello.txt"".

/Users/stronk7/git_moodle/moodle/lib/tests/moodlelib_test.php:3487
/Users/stronk7/git_moodle/moodle/lib/phpunit/classes/advanced_testcase.php:80

FAILURES!
Tests: 8, Assertions: 23, Failures: 1.