Using `&&` in `BOOST_CHECK` is problematic as failures will not indicate
which condition failed. By unrolling these checks, the user knows
exactly which expression is the failing case.
As an example, here is a line that would be particularly hard to debug
if it failed:
```
src/test/net_tests.cpp
BOOST_CHECK((*ret)[1] && (*ret)[1]->m_type == "headers" && std::ranges::equal((*ret)[1]->m_recv, MakeByteSpan(msg_data_2)));
```
If any one of these conditions fail, the whole expression fails, with no
values printed or indication as to which condition failed.
This is also required when using test macros that support value
decomposition, which requires `&&` and `||` are `delete`. Examples
include `BOOST_TEST`, doctest, Catch2, etc.
ref: https://catch2-temp.readthedocs.io/en/latest/assertions.html#other-limitations
ref: https://fekir.info/post/decomposing-an-expression/
We don't need so much access to the internals of CCoinsCacheEntry, since many tests are just exercising invalid combinations this way.
This implies that `AddFlags` has private access now.
CCoinsCacheEntry provided general access to its internal flags state, even though in reality it could only be clean, fresh, dirty or fresh|dirty.
After it got dirtied we couldn't set the state back to clean by AddFlags(0) - tests were explicitly checking against that.
This commit cleans up the public interface to make this distinction cleaner and invalid behavior impossible instead of just checked by tests.
This includes the removal of redundant `inline` qualifiers (we're inside a struct).
Also renamed `self` to `pair` to simplify the upcoming commits.
Also modernized `EmplaceCoinInternalDANGER` since it was already modified.
Co-authored-by: Andrew Toth <andrewstoth@gmail.com>
