What rules are available by default in a RuleRunner? None? Some? For context, I'm writing a unit test which has to go through a target generator. The target generator works outside the test, but inside the test it fails with:

E         No installed rules return the type GenerateCargoTargetsRequest, and it was not provided by potential callers of @rule(pants_cargo_porcelain.target_types:172:generate_cargo_generated_target(GenerateCargoTargetsRequest, RustSubsystem, RustupTool) -> GeneratedTargets, gets=[Get(SourceFiles, [SourceFilesRequest]), Get(RustToolchain, [RustToolchainRequest]), Get(ProcessResult, [CargoProcessRequest])]).

My runner is dumb as rocks:

rule_runner = RuleRunner(
        rules=[
            *register.rules(),
            *clippy_register.rules(),
            QueryRule(Partitions, [CargoClippyRequest.PartitionRequest]),
            # QueryRule(LintResult, [CargoClippyRequest.Batch]),
        ],
        target_types=register.target_types(),
    )

Which at this point is everything in the plugin.

register.rules()

bundles the following from my target types.

def rules():
    return [
        *collect_rules(),
        UnionRule(GenerateTargetsRequest, GenerateCargoTargetsRequest),
    ]

But I'm guessing this happens "one step up" where something has to do a union lookup...

these are the default built in rules all schedulers have: https://github.com/pantsbuild/pants/blob/78111bbc105418dc2f419181e67c8ec2f80f439a/src/python/pants/init/engine_initializer.py#L241-L298

Thank you, great links. I ended up just throwing rule bundles onto it until it worked. As with all rule issues; the issue was somewhere else - I needed to add

external_tool.rules()

and

source_files.rules()

.