## Checklist
- [x] I have read the [contribution guidelines](https://github.com/ooni/probe-cli/blob/master/CONTRIBUTING.md)
- [x] reference issue for this pull request: https://github.com/ooni/probe/issues/1885
- [x] related ooni/spec pull request: N/A
Location of the issue tracker: https://github.com/ooni/probe
## Description
This PR contains a set of changes to move important interfaces and data types into the `./internal/model` package.
The criteria for including an interface or data type in here is roughly that the type should be important and used by several packages. We are especially interested to move more interfaces here to increase modularity.
An additional side effect is that, by reading this package, one should be able to understand more quickly how different parts of the codebase interact with each other.
This is what I want to move in `internal/model`:
- [x] most important interfaces from `internal/netxlite`
- [x] everything that was previously part of `internal/engine/model`
- [x] mocks from `internal/netxlite/mocks` should also be moved in here as a subpackage
They are now more readable. I'll do another pass and start
separating integration testing from unit testing.
I think we need to have some always on integration testing
for netxlite that runs on macOS, linux, and windows.
See https://github.com/ooni/probe/issues/1591
Like before, do not touch the rest of the tree. Rather create
compatibility types declared as legacy.
We will soon be able to close idle connections for an HTTP3
transport using any kind of resolvers more easily.
See https://github.com/ooni/probe/issues/1591
This quirk really saddens me. It's a piece of tech debt we're
carrying over from the original netx implementation.
We cannot remove it _until_ we have legacy netx code around.
The second best thing we can do is to clearly move this code in
a place where it's clear it's a quirk and write and use some extra
code that makes sure the quirk's assumptions are always met.
Sigh.
See https://github.com/ooni/probe/issues/1591
Like we did before for the resolver, a dialer should propagate the
request to close idle connections to underlying types.
See https://github.com/ooni/probe/issues/1591
We would like to refactor the code so that a DoH resolver owns the
connections of its underlying HTTP client.
To do that, we need first to incorporate CloseIdleConnections
into the Resolver model. Then, we need to add the same function
to all netxlite types that wrap a Resolver type.
At the same time, we want the rest of the code for now to continue
with the simpler definition of a Resolver, now called ResolverLegacy.
We will eventually propagate this change to the rest of the tree
and simplify the way in which we manage Resolvers.
To make this possible, we introduce a new factory function that
adapts a ResolverLegacy to become a Resolver.
See https://github.com/ooni/probe/issues/1591.
* refactor(netxlite): make sure we always use netmocks
While there, improve logging and make sure we test 100% of the
package with unit tests only. (We don't need to have integration
testing in this package because it's fairly simple/obvious.)
Part of https://github.com/ooni/probe/issues/1505
* further improve logs
What do I mean by pivoting? Netx is currently organized by row:
```
| dialer | quicdialer | resolver | ...
saving | | | | ...
errorwrapping | | | | ...
logging | | | | ...
mocking/sys | | | | ...
```
Every row needs to implement saving, errorwrapping, logging, mocking (or
adapting to the system or to some underlying library).
This causes cross package dependencies and, in turn, complexity. For
example, we need the `trace` package for supporting saving.
And `dialer`, `quickdialer`, et al. need to depend on such a package.
The same goes for errorwrapping.
This arrangement further complicates testing. For example, I am
currently working on https://github.com/ooni/probe/issues/1505 and
I realize it need to repeat integration tests in multiple places.
Let's say instead we pivot the above matrix as follows:
```
| saving | errorwrapping | logging | ...
dialer | | | | ...
quicdialer | | | | ...
logging | | | | ...
mocking/sys | | | | ...
...
```
In this way, now every row contains everything related to a specific
action to perform. We can now share code without relying on extra
support packages. What's more, we can write tests and, judding from
the way in which things are made, it seems we only need integration
testing in `errorwrapping` because it's where data quality matters
whereas, in all other cases, unit testing is fine.
I am going, therefore, to proceed with these changes and "pivot"
`netx`. Hopefully, it won't be too painful.
