By just storing the raw certificate we simplify the internal data
structure we use. In turn, this enables us to write better unit tests
using github.com/google/go-cmp where we can construct the expected
result and compare with that. (Yeah, in principle we could also
construct the full certificate but I'm not sure it's worth the effort
since we basically only care about the raw certificate.)
The general idea here is to make tracex more tested. Once it's more
tested, I will create separate structs for each event, which is
something that measurex also does. Once that is done, we can start
ensuring that the code in measurex and the code in tracex do the
same thing in terms of storing observations. When also this is done,
we can then rewrite measurex to use tracex directly.
The overall goal is https://github.com/ooni/probe/issues/2035.
There are two reasons why this is beneficial:
1. github.com/google/go-cmp is more annoying to use for comparing
data structures when there are interfaces to compare. Sure, there's
a recipe for teaching it to compare errors, but how about making
the errors trivially comparable instead?
2. if we want to send errors over the network, JSON serialization
works but we cannot unmarshal the resulting string back to an error,
so how about making this representation trivial to serialize (we
are not going this now, but we need this property for websteps and
it may be sensible to try to avoid to have duplicate code because
of that -- measurex currently duplicates many tracex functionality
and this is quite unfortunate because it slows development down)
Additionally, if an error is a string:
3. we can very easily use a switch for comparing its possible
values with "" representing the absence of errors, while it is
more complex to do the same when using a nullable string or even
an error (i.e., an interface)
4. if a type is not nullable, it's easier to write safe code for
it and we may want to refactor experiments to use the internal
representation of measurements for more robust processing code
For all these reasons, let's internally use strings in tracex.
The overall aim here is to reduce the duplicated code between pre
and post-measurex measurements (see https://github.com/ooni/probe/issues/2035).
* refactor: move tracex outside of engine/netx
Consistently with https://github.com/ooni/probe/issues/2121 and
https://github.com/ooni/probe/issues/2115, we can now move tracex
outside of engine/netx. The main reason why this makes sense now
is that the package is now changed significantly from the one
that we imported from ooni/probe-engine.
We have improved its implementation, which had not been touched
significantly for quite some time, and converted it to unit
testing. I will document tomorrow some extra work I'd like to
do with this package but likely could not do $soon.
* go fmt
* regen tutorials
