proposal: testing: add (*testing.F).AddNamed() for naming seed corpus entries

[mateusz834]

Proposal Details

Currently the corpus entries ("sub-tests") added by (*testing.F).Add() are named like: FuzzMyFuzz/seed#0. In my case i am populating the fuzz corpus with file contents from the testdata directory, because of the default naming there is no easy way to quickly map seed corpus to a file (for -run, to run only one test from the corpus), to do so i need to t.Log the file contents in the f.Fuzz and figure out which file contains that data, this is annoying, especially that while adding a corpus entry the file name is known.

I propose to add following function to the testing package to solve this issue:

// AddNamed will add the arguments to the seed corpus for the fuzz test with a specified name.
// This will be a no-op if called after or within the fuzz target, and args must match the
// arguments for the fuzz target.
func (f *F) AddNamed(name string, args ...any)

[gabyhelp]

Related Issues and Documentation

• proposal: testing: support naming seed corpus values provided with (*testing.F).Add #50456 (closed)
• Package testing > type F ¶ 1.18 > func (*F) Add ¶ 1.18
• cmd/go: use testdata/fuzz not testdata/corpus for fuzzing #48128 (closed)

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[mateusz834]

This is relevant #50456 (TLDR: Add should behave as the AddNamed proposed here, not possible now because of breaking API changes)

It sounds like this is either a likely decline or a 'on hold'. Given that we are not making changes for Go 1.18, perhaps it should be declined for now, and then a new proposal with a different API can be proposed if we need it?

[ianlancetaylor]

CC @golang/fuzzing