How to use it with main.rs instead of lib.rs

[MathieuSoysal]

Hello, first thank you for your awesome project

I'm new in the rust world, and I wanted to test your fuzzing project.

But when I want to test it inside my test project https://github.com/MathieuSoysal/Exercism-Rust-Template/tree/3-add-fuzzing-tests

I obtain this error cargo fuzz build:

warning: unused manifest key: package.escription
warning: template-exercisme-fuzz v0.0.0 (/workspaces/Exercism-Rust-Template/fuzz) ignoring invalid dependency `template_exercisme` which is missing a lib target
   Compiling template-exercisme-fuzz v0.0.0 (/workspaces/Exercism-Rust-Template/fuzz)
error[E0432]: unresolved import `template_exercisme`
 --> fuzz_targets/fuzz_play_game.rs:6:5
  |
6 | use template_exercisme::play_game;
  |     ^^^^^^^^^^^^^^^^^^ use of undeclared crate or module `template_exercisme`

warning: unused `#[macro_use]` import
 --> fuzz_targets/fuzz_play_game.rs:4:1
  |
4 | #[macro_use] extern crate libfuzzer_sys;
  | ^^^^^^^^^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

For more information about this error, try `rustc --explain E0432`.
warning: `template-exercisme-fuzz` (bin "fuzz_play_game") generated 1 warning
error: could not compile `template-exercisme-fuzz` (bin "fuzz_play_game") due to 1 previous error; 1 warning emitted
Error: failed to build fuzz script: ASAN_OPTIONS="detect_odr_violation=0" RUSTFLAGS="-Cpasses=sancov-module -Cllvm-args=-sanitizer-coverage-level=4 -Cllvm-args=-sanitizer-coverage-inline-8bit-counters -Cllvm-args=-sanitizer-coverage-pc-table -Cllvm-args=-sanitizer-coverage-trace-compares --cfg fuzzing -Clink-dead-code -Zsanitizer=address -Cllvm-args=-sanitizer-coverage-stack-depth -Cdebug-assertions -C codegen-units=1" "cargo" "build" "--manifest-path" "/workspaces/Exercism-Rust-Template/fuzz/Cargo.toml" "--target" "x86_64-unknown-linux-gnu" "--release" "--config" "profile.release.debug=true" "--bins"

Someone can help me ?

[kpcyrd]

The way this works is, your fuzz/ subfolder has a dependency on your template_exercisme crate:

[dependencies.template_exercisme]
path = ".."

This fails because you're missing a src/lib.rs file, if you crate one with touch src/lib.rs you get a different error:

error[E0432]: unresolved import `template_exercisme::play_game`
 --> fuzz_targets/fuzz_play_game.rs:6:5
  |
6 | use template_exercisme::play_game;
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no `play_game` in the root

warning: unused `#[macro_use]` import
 --> fuzz_targets/fuzz_play_game.rs:4:1
  |
4 | #[macro_use] extern crate libfuzzer_sys;
  | ^^^^^^^^^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

For more information about this error, try `rustc --explain E0432`.
warning: `template-exercisme-fuzz` (bin "fuzz_play_game") generated 1 warning
error: could not compile `template-exercisme-fuzz` (bin "fuzz_play_game") due to 1 previous error; 1 warning emitted

There's no way to access functions in src/main.rs for library consumers, so if you want to fuzz a function it needs to be in src/lib.rs (or any other module that get's made available by src/lib.rs).

In your src/main.rs you can make use of functions in src/lib.rs (just not the other way around). In your src/main.rs you'd write something like:

use template_exercisme::play_game;