Linking against python for tests that depend on a pyo3_extension

[maffoo]

We have a pyo3_extension target which builds a python extension module. As I understand it, this builds as if the extension-module feature is enabled so that the library does not link against python. But in some tests we would like to link against libpython so that tests can use pyo3 features such as PyResult. Is there any documentation about how to do this with rules_rust? In cargo we can disable the extension-module feature when running tests and everything works as expected. Is there a dependency I can get from a rules_python toolchain for example to link libpython into a particular rust_test target?

[UebelAndre]

I don't think there is documentation for this. I think I need to make some changes to enforce that consumers provide their own toolchain where more of these decisions can be made externally. But can you provide an example of what you're trying to do? My initial thoughts are if you provide your own toolchain you can accomplish what I think you're trying to do as you would then control all the features of pyo3.

[maffoo]

We are settings up a rust_pyo3_toolchain and then we have a BUILD.bazel like the following:

pyo3_extension(
    name = "foo",
    srcs = glob(["src/**/*.rs"]),
    deps = [
        "@crates//:anyhow",
        ...
    ],
)

rust_test(
    name = "foo_test",
    crate = ":foo_shared",  # from the pyo3_extension macro
    deps = [
        "@crates//:test-case",
        # <-- NEED to add libpython here
    ],
)

We also have a python toolchain configured as the full bazel workspace contains both python and rust code, so maybe there's a way to get a lib python dependency from the rules_python toolchain if not from the rust_pyo3_toolchain?