The requirements test for transaction_isolation checks against a wrong version

As the change in the title loses the context, added it to the description of the problem. Hope users still find when searching for the symptom, not knowing the cause of it.

@immaculatexavier thanks for the MR, exactly what I was l was looking for.
Suspect I am not allowed to RTBC, otherwise I would.

Added possible refactor.

For testing you need several versions of MySQL, 8.0.0, 8.0.1, 8.0.2 and 8.0.3

You can use any version of D10 up till and including beta1. You shouldn't need dev of 10.0 or 10.1.

To test you only request the status report. Getting the report is prove it works. The message about the isolation is irrelevant. So, no need for different values. The variable names are the matter of the issue.

The proposed refactor would deal with multiple settings, preferring 'transaction_isolation'.

Confirm the change is correct for 8.0.0,8.0.1,8.0.2 and 8.0.3.

Faked MySQL versions by adjusting line 276 of core/modules/mysql/src/Driver/Database/mysql/Connection.php returning hardcoded values. Obviously, 8.0.3 resulted in WSOD as no transaction_isolation variable exist in 8.0.2-dmr.

Considered it minor as these MySQL versions are from 2017. Currently GA 8.0.30 (2022-07-26)
See https://dev.mysql.com/doc/relnotes/mysql/8.0/en/news-8-0-30.html

Found it here: https://dev.mysql.com/doc/refman/8.0/en/added-deprecated-removed.html first.
Also mentioned in the release notes: https://dev.mysql.com/doc/relnotes/mysql/8.0/en/news-8-0-3.html

Would prefer the early stage approach as mentioned as refactor in Remaining tasks.

There is no need for conditionals on MySQL version:

    20	      $query = 'SHOW VARIABLES LIKE \'%_isolation\'';

    21	      $isolation_levels = $connection->query($query)->fetchAllKeyed();
    22	      $isolation_level = $isolation_levels['transaction_isolation'] ?? "";
    23	      if (empty($isolation_level)) {
    24		      $isolation_level = $isolation_levels['tx_isolation'] ?? "Not set";
    25	      }

When you insist on documentation suggest to add a line: Retrieve transaction_isolation with fallback on tx_isolation.

Provided the refactor in #15

@longwave That would be irrelevant, as you can read from the code it is checking for tx_isolation and transaction_isolation explicitly. Assuming transaction_isolation to be set, falling back to tx_isolation for the first three releases. The %_isolation is for getting these values and possibly others. In addition that way it is checking the run-time, not the theory/documentation.

Added benefit is that it is no longer MySQL specific.

In that case, I can only hope you are going to be overruled by others. Hopefully, there are people that understand that your concern is ridiculous.

It is clear I am wasting my time here. Already provided the code, happily using it.