Tests Involving Decimal and Currency Separators

[oleibman]

This was suggested by the investigation of issue #3811. No fix is necessary for the issue. However, two possible code solutions (Php setlocale, which comes with certain design flaws, and StringHelper set(Decimal/Thousands)Separator were suggested, and neither is adequately tested. This PR adds such tests.

Unusually, getting StringHelper Decimal Separator, Thousands Separator, and Currency Code can result in a change to those properties. So, the existing design in several tests where those properties are captured in Setup and restored in Teardown do not work quite as designed. Instead, the ability to set those properties to their default value (null) is added, and the tests re-done to restore the default in Teardown.

The two methods yield the same results when parsing input. However, they diverge when examining output fields through getFormattedValue. Such output is currently correct (usually) when using setlocale, but not when using StringHelper. The former works through the 'trick' of using sprintf(%f), which generates a locale-aware string. However, using non-locale-aware sprintf(%F) followed by str_replace will produce the correct result for both setlocale and StringHelper. One place in the code uses a cast to string, which is incorrect for both methods. Following that up with the same str_replace makes it correct for both. These changes permit, but do not require, the user to avoid setlocale altogether.

It remains an open question whether Settings/Calculation::setLocale should set DecimalSeparator, CurrencySeparator, and CurrencyCode. That makes logical sense, but it would be a breaking change, and having to explicitly set those values when using setLocale does not seem especially burdensome. For now, such a change will not be made.

This is:

• a bugfix
• a new feature
• refactoring
• additional unit tests

Checklist:

• Changes are covered by unit tests
  • Changes are covered by existing unit tests
  • New unit tests have been added
• Code style is respected
• Commit message explains why the change is made (see https://github.com/erlang/otp/wiki/Writing-good-commit-messages)
• CHANGELOG.md contains a short summary of the change and a link to the pull request if applicable
• Documentation is updated as necessary

Why this change is needed?

Provide an explanation of why this change is needed, with links to any Issues (if appropriate).
If this is a bugfix or a new feature, and there are no existing Issues, then please also create an issue that will make it easier to track progress with this PR.