test: remove api that should not be used

[julienrbrt]

Description

ref: #12332 (comment)
Given the sync in the standup, just removing the helper with had introduced for v0.48, for the API lacking of gotest.tools.
As going forward, we still use testify assertions, we can simply delete them, and add a proto deep equal helper.
We need to remove them now for ensuring that no one uses them.

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[mark-rushakoff]

Function name and doc could be slightly more clear, but everything else looks like a simple mechanical refactor.

[mark-rushakoff]

RequireProtoDeepEqual is probably a better function name.

RequireProtoDeepEqual fails the test t if p1 and p2 are not equivalent protobuf messages.

[julienrbrt]

And this is why I am going to request reviews from you more often :D

[mark-rushakoff]

For that matter, I think p1 and p2 should be of type proto.Message iirc.

[julienrbrt]

cmp.Diff accepts interface{}, so I think we should accept interfaces as well.

[mark-rushakoff]

cmp.Diff does accept any, but I'm not sure what the intended behavior is if a programmer mistakenly passes a non-proto.Message type when using protocmp.Transform. If there is a runtime failure in that case, then it would be better to fail earlier, at compile time.

[mark-rushakoff]

Oh, maybe proto.Message would be too restrictive if you were comparing slices instead. Maybe the doc should mention that the function can handle values or slices in the case of continuing to accept any for p1 and p2.