Test binary is looked up in unit tests which relies on internals of Cargo and will break with existing / upcoming features

[epage]

Tests assumes the location of build artifacts

• This isn't the case when a user sets build.build-dir (added as of Cargo 1.91)
• This isn't the case if we approve the new build-dir layout (Re-organize build-dir by package + hash, rather than artifact type rust-lang/cargo#15010)
• This isn't the case if we change the build.build-dir default (Move build-dir out of the workspace to cargo-cache-home by default rust-lang/cargo#16147)

You can reproduce this by running either:

$ cargo +nightly test -Zbuild-dir-new-layout
$ CARGO_BUILD_BUILD_DIR=build cargo test

Move the tests and possibly upgrade the underlying testing library (assert_cmd, snapbox, etc). If manually implementing binary lookup and needing to update the implementation, see assert_cmd::cargo::cargo_bin for an example.

This problem was identified by the following crater run: rust-lang/rust#149852