timings, too short
<link rel="help" href="https://w3c.github.io/webvtt/#collect-a-webvtt-timestamp">

assert_equals(cues.length, 2);

assert_equals(cues[0].text, 'text0');
assert_equals(cues[0].startTime, 0);
assert_equals(cues[0].endTime, 1);

assert_equals(cues[1].text, 'text1');
assert_equals(cues[1].startTime, 0);
assert_equals(cues[1].endTime, 1);

===
WEBVTT

0:00:00.000 --> 00:00:01.000
text0

0000:00.000 --> 00:00:01.000
invalid

00:0:00.000 --> 00:00:01.000
invalid

00:0000.000 --> 00:00:01.000
invalid

00:00:0.000 --> 00:00:01.000
invalid

00:00:00000 --> 00:00:01.000
invalid

00:00:00.00 --> 00:00:01.000
invalid

00:00:00.0 --> 00:00:01.000
invalid

00:00:00. --> 00:00:01.000
invalid

00:00:00 --> 00:00:01.000
invalid

00:00:0 --> 00:00:01.000
invalid

00:00: --> 00:00:01.000
invalid

00:00 --> 00:00:01.000
invalid

00:0 --> 00:00:01.000
invalid

00: --> 00:00:01.000
invalid

00 --> 00:00:01.000
invalid

0 --> 00:00:01.000
invalid

 --> 00:00:01.000
invalid

0:00.000 --> 00:01.000
invalid

0000.000 --> 00:01.000
invalid

00:0.000 --> 00:01.000
invalid

00:00000 --> 00:01.000
invalid

00:00.00 --> 00:01.000
invalid

00:00.0 --> 00:01.000
invalid

00:00. --> 00:01.000
invalid

0:00. --> 00:01.000
invalid

:00. --> 00:01.000
invalid

00. --> 00:01.000
invalid

0. --> 00:01.000
invalid

. --> 00:01.000
invalid

00:00.000 --> 0:01.000
invalid

00:00:00.000 --> 0:00:01.000
text1