We recently started moving core data structures inside of the
internal/model package as detailed in https://github.com/ooni/probe/issues/1885.
The chief reason to do that is to have a set of fundamental
shared data types to help us rationalize the codebase.
This specific diff moves internal/netx/archival's core data types
inside the internal/model package. While there, it also refactors the
existing tests to improve their quality. Additionally, we also added
an extra test to ensure `ArchivalHTTPBody` is an alias for
`ArchivalMaybeBinaryData`, which is required to ensure the
custom JSON serialization process works for it.
We're doing that because both internal/netx/archival and
internal/measurex define their own archival data structures.
We developed measurex using its own structures because it
allowed to iterate more quickly. Now that we have sketched
out measurex, the time has come to consolidate.
My overall aim is to spend a few more hours this week on
engineering measurex. This work is preliminary work before
we finish up both measurex and websteps.
We described this cleanup in https://github.com/ooni/probe/issues/1957.
Since https://github.com/ooni/probe-cli/pull/527, if an experiment
returns an error, the corresponding measurement is not submitted since
the semantics of returning an error is that something fundamental
went wrong (e.g., we could not parse the input URL).
This diff ensures that all experiments only return and error when
something fundamental was wrong and return nil otherwise.
Reference issue: https://github.com/ooni/probe/issues/1808.
## 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
