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FAQ and common errors

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Dániel Buga edited this page Jan 27, 2025 · 6 revisions

Most common errors:

error[E0463]: can't find crate for test

This can happen if you forget to add harness = false to your Cargo.toml for each test.

Furthermore, this error can happen if you invoke cargo test without any additional arguments. Apparently cargo test wants to also test the binaries...

Adding the following to Cargo.toml helps as a workaround.

[[bin]]
name = "embedded-example-test"
path = "src/main.rs"
+ test = false

Alternatively, you can also run cargo test --tests to only run the integration tests.

rust-lld: error: undefined symbol: embedded_test_linker_file_not_added_to_rustflags

Make sure you've added the following line to your build.rs linker script:

println!("cargo::rustc-link-arg-tests=-Tembedded-test.x");

You can also add rustflags = [ "-C", "link-arg=-Tembedded-test.x" ] to your .cargo/config.toml file. But then you need to move embedded-test from [dev-dependencies] to [dependencies] in your Cargo.toml.

rust-lld: error: duplicate symbol: _SEGGER_RTT

You probably have the init-log feature activated on embedded-test while at the same time using a crate like defmt-rtt or rtt-log. You need to either setup the logger yourselve (with a crate of your choice) or let embedded-test do it (init-log feature)

probe-rs exits directly after flashing (semihosting...)

Make sure you're using at least probe-rs 0.24.0. Older versions do not support embedded-test yet.

probe-rs complains about unexpected arguments

Make sure you're using at least probe-rs 0.24.0. Older versions do not support embedded-test yet.
Otherwise, please open an issue including the commandline that was used to invoke probe-rs.

probe-rs fails to link when using embedded-test with defmt 

  = note: rust-lld: error: undefined symbol: _defmt_release
          >>> referenced by mod.rs:71
          ...

If only your test builds fail but your main application builds fine, you probably have some linker scripts that are not linked for the tests but are linked for the main application.

Check your build.rs for println!("cargo:rustc-link-arg-bins=-Tdefmt.x"); or some other dependency which might be missing. Add println!("cargo:rustc-link-arg-tests=-Tdefmt.x"); or some other dependency which might be missing. to your build.rs.

probe-rs fails to link when using embedded-test with defmt-rtt

If you're using defmt-rtt rather than rtt-target you will have to use defmt-rtt within your test code. This can be done with use defmt_rtt as _; at the top of your test file.

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