fix(ut): use valid UTF8 sequence instead

[SchrodingerZhu]

Signed-off-by: SchrodingerZhu i@zhuyi.fan

What problem does this PR solve?

Issue Number: close #4280

Problem Summary:

The last attempt did not eliminate the warnings. After debugging, we can see that utf8.convert give back a -1 as a character and then it is passed to the properties function, where -1 is used in index calculation. I guess Poco is not robust enough at handling invalid char sequence. Using predefined valid sequence fixes the problem.

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• JaySon-Huang
• fuzhe1989

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[SchrodingerZhu]

/merge

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[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: d57341e

[ti-chi-bot]

@SchrodingerZhu: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

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[sre-bot]

Coverage for changed files

Filename                                                                                                                   Regions    Missed Regions     Cover   Functions  Missed Functions  Executed       Lines      Missed Lines     Cover    Branches   Missed Branches     Cover
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
/home/jenkins/agent/workspace/tiflash-build-common/tiflash/dbms/src/Functions/tests/gtest_strings_simd_consistency.cpp         171                 8    95.32%           7                 0   100.00%         285                 2    99.30%         100                23    77.00%
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
TOTAL                                                                                                                          171                 8    95.32%           7                 0   100.00%         285                 2    99.30%         100                23    77.00%

Coverage summary

Functions  MissedFunctions  Executed  Lines   MissedLines  Cover
16976      9545             43.77%    191278  96846        49.37%

full coverage report (for internal network access only)