ValidationInfo

Provider declaring how a target should be validated.

When a target carrying ValidationInfo is reachable via a transitive dependency edge from a target requested on the command line (e.g. buck2 build, buck2 test), Buck2 schedules every ValidationSpec it carries before the requested action is considered complete. A failed required validation causes the build to fail; an optional validation is skipped unless the user opts in via --enable-optional-validations <name>.

Validations run in parallel with the build of the requested target — they only have to finish before Buck2 reports success.

Constraints enforced at construction / freezing time:

• validations must be a non-empty list of ValidationSpec values.
• Spec names must be unique within the provider.

Example:

def _my_rule_impl(ctx):
    report = ctx.actions.declare_output("validation.json")
    ctx.actions.run(
        cmd_args("validator", "--out", report.as_output(), ctx.attrs.src),
        category = "my_validation",
    )
    return [
        DefaultInfo(default_output = ctx.attrs.src),
        ValidationInfo(validations = [
            ValidationSpec(name = "schema_check", validation_result = report),
        ]),
    ]

See the Validations guide for the end-to-end story.

ValidationInfo.validations

ValidationInfo.validations: list[ValidationSpec]

Non-empty list of ValidationSpec values, each representing a single validation. Spec names must be unique within this provider.

See the Validations guide for how to declare validations end-to-end and write the validator action that produces each spec's validation_result.