IndexShardTests. testIndexCheckOnStartup logging assertion failure

[pgomulka]

Build scan:
https://gradle-enterprise.elastic.co/s/gr6v5hnejapom
Repro line:
gradlew ':server:test' --tests "org.elasticsearch.index.shard.IndexShardTests.testIndexCheckOnStartup" -Dtests.seed=CFA13989D09C1401 -Dtests.locale=ms-MY -Dtests.timezone=America/North_Dakota/Beulah -Druntime.java=11
Reproduces locally?:
yes, on windows
Applicable branches:
master, on windows
Failure history:
new failure after #74233
Failure excerpt:

java.lang.AssertionError: expected to see failure message but did not
12:42:33     Expected: <true>
12:42:33          but: was <false>
12:42:33         at __randomizedtesting.SeedInfo.seed([CFA13989D09C1401:CE07EC20DA1AD6D9]:0)
12:42:33         at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:18)
12:42:33         at org.elasticsearch.test.MockLogAppender$SeenEventExpectation.assertMatched(MockLogAppender.java:121)
12:42:33         at org.elasticsearch.test.MockLogAppender.assertAllExpectationsMatched(MockLogAppender.java:55)
12:42:33         at org.elasticsearch.index.shard.IndexShardTests.testIndexCheckOnStartup(IndexShardTests.java:3117)

but the logs contain the expected log lines..

12:42:33   1> [2021-06-18T05:42:15,619][WARN ][o.e.i.s.IndexShard       ] [testIndexCheckOnStartup] [index][0] performing expensive diagnostic checks during shard startup [index.shard.check_on_startup=checksum]; these checks should only be enabled temporarily, you must remove this index setting as soon as possible
12:42:33   1> [2021-06-18T05:42:15,625][WARN ][o.e.i.s.IndexShard       ] [testIndexCheckOnStartup] [index][0] check index [failure]
12:42:33   1> checksum passed: _0.cfe
12:42:33   1> checksum passed: _0.si
12:42:33   1> checksum failed: _0.cfs
12:42:33   1> org.apache.lucene.index.CorruptIndexException: checksum failed (hardware problem?) : expected=e72f63ce actual=df4db7c6 (resource=BufferedChecksumIndexInput(MockIndexInputWrapper(NIOFSIndexInput(path="C:\Users\jenkins\workspace\platform-support\91\server\build\testrun\test\temp\org.elasticsearch.index.shard.IndexShardTests_CFA13989D09C1401-001\tempDir-114\indices\_na_\0\index\_0.cfs")))

I wonder if this is windows related. It passes for me on macos

[pgomulka]

I dicussed this with @dct and it turns out to be a problem with a regex in MockLogAppender

public MockLogAppender() throws IllegalAccessException {
        super("mock", RegexFilter.createFilter(".*(\n.*)*", new String[0], false, null, null), null, false);