test: check error code lines with regex in Bats

[AirQuick]

Saxon 10 changed the way it prints errors.

Printing error(xs:QName('errCode'), 'errDescription') is changed as follows.

-  errCode: errDescription
+  errCode  errDescription

To get ready for that change in Bats test, this pull request replaces some checks with regular expression. Also, to make future changes easier, this pull request wraps some existing regular expression tests in a helper function.

c8a1e40 is a temporary commit to verify that the regular expression is still able to detect test failures.

[commit-lint]

Tests

• store error code regex in variable in xspec.bats (15a6a0c)
• store error code line in variable in xspec.bats (5820414)
• check error code lines with regex in Bats (f66bbae)
• use helper function instead of regex variable (c582c16)

Continuous Integration

• add Saxon 10.0 to CI matrix (c8a1e40)

Contributors

@AirQuick

[AirQuick]

With the temporary commit, Bats test failed at the regular expression tests on Azure Pipelines and Travis CI only on Saxon 10, which effectively verified this PR.