#2772: PhContainingUTF8 to print strings correctly

[levBagryansky]

Closes #2772

Such eo code like

[] > my-error
  error > @
    "qwerty"

failed with unclear message since PhDefault::toString() implementation. So PhContainingUTF8 was introduced.

---

PR-Codex overview

This PR focuses on adding unit tests for the EOerror class and improving the error message handling.

Detailed summary

• Added unit tests for EOerror class.
• Imported necessary dependencies for unit tests.
• Implemented getsReadableError test method.
• Added getTestSources method to provide input arguments for the test.
• Added MyError class to create a custom error object for testing.
• Improved error message handling in the ExError class.
• Added safeMessage method to safely retrieve the message from the enclosure.

✨ Ask PR-Codex anything about this PR by commenting with /codex {your question}

[levBagryansky]

@maxonfjvipon please take a look

[maxonfjvipon]

@levBagryansky good one, just several comments from my side

[maxonfjvipon]

@levBagryansky can we make this variable final?
For example set it to null in try block and set to exc in catch block?

[levBagryansky]

@maxonfjvipon We cannot do it here, I get the error Variable 'error' might already have been assigned to: 73

[maxonfjvipon]

@levBagryansky one more question: do we have a case where object inside ExError can't be dataized at all?

[levBagryansky]

@maxonfjvipon this is a good question..

[levBagryansky]

@maxonfjvipon please check

[maxonfjvipon]

@levBagryansky LGTM! Thanks

[levBagryansky]

@yegor256 please take a look

[yegor256]

@levBagryansky if this class is an instance of Phi and it makes phi objects safer by properly printing their toString(), why do we use only here, in this private method? Why don't we decorate all our phi objects with this decorator?

[levBagryansky]

@yegor256 This class is correctly to use in order to print bytes of data as UTF8 String. For example, PhContainingUTF8(EOint) produces something strange. We can also use this class in Data.ToPhi(java.util.String)

[yegor256]

@levBagryansky maybe we shouldn't call this class Phi... and should not make it a decorator of Phi? It doesn't look like a decorator to me, but a "smart" class: https://www.yegor256.com/2016/04/26/why-inputstream-design-is-wrong.html It just takes an existing instance of Phi, calls its method and then post-process the returned data. It doesn't become phi, it only is a client of Phi.

[levBagryansky]

@yegor256 @maxonfjvipon , PhDefault::toString has the following implementation:

    @Override
    public String toString() {
        String result = String.format(
            "%sν%d",
            this.getClass().getCanonicalName(),
            this.vertex
        );
        if (this.attrs.containsKey("Δ")) {
            result = String.format(
                "%s=%s",
                result,
                this.attrs.get("Δ").toString()
            );
        }
        return result;
    }

So EOstring::toString does not print its content because EOstring has φ attribute with EObytes inside, not Δ. But we need to print Phi objets correctly somehow for readable exceptions. Ideally, making it correctly in cases of EOint, EOstrings. EOfloat and so on.
May be we will create such decorators and wrap to them in to-java.xsl?