BoundaryML/baml · error

Test ' ' not found for expr function

Error message

Test '{}' not found for expr function '{}'

What it means

This error is thrown by get_test_type_builder_impl when a named test cannot be located for an expr-function in the BAML IR. The runtime looked up the expr function via find_expr_fn, then searched its attached tests with find_test(test_name) and got None, so it reports which test name and which function name were requested. It exists to surface typos/stale test references in the baml_src test definitions rather than silently returning no type builder.

Solutions

1. Check the test name spelling and that it is declared inside the specified expr function in your .baml files
2. Regenerate/refresh the BAML runtime IR (rebuild or re-run baml-cli generate) after editing baml_src
3. List the existing tests for the expr function and run one of those instead
4. If the test lives on another function, pass the correct function_name to the call

Example fix

// before
let tb = runtime.get_test_type_builder("MyFunction", "my_test", &ctx).await?;
// after
// baml_src now defines `test my_test { ... }` inside MyFunction,
// or the call uses the correct function name:
let tb = runtime.get_test_type_builder("MyFunction", "correct_test_name", &ctx).await?;

// Rust: verify the test exists before requesting its type builder
let expr_fn = runtime.ir().find_expr_fn(function_name)?;
if expr_fn.find_test(test_name).is_none() {
    return Err(anyhow!("test '{test_name}' not defined for '{function_name}'"));
}

When it happens

Trigger: Calling get_test_type_builder (or run_test_with_expr_events, which calls it) with a test_name that is not defined under the expr function named function_name in the compiled BAML sources.

Common situations: Typo in the test name passed to the CLI or test runner; the test was renamed or deleted from the .baml file while an old harness still references it; running a test defined on a different function than the one given; partially generated/stale IR after editing baml_src.

Understand the failure class

Background: Record Not Found Errors: "not found", RecordNotFound, and "was not found" — what they mean and how to fix them — this error's family across 28 libraries.

Related errors

• {0}
• BAML Generate failed - Project has errors.
• ======================================== BAML Internal…
• baml.panics.DivisionByZero
• Configuration error

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/a363360358da5803. Report an issue: GitHub.

Appendix: source

Thrown at engine/baml-runtime/src/lib.rs:880

            let type_builder = TypeBuilder::new();
            type_builder.add_entries(test.type_builder_contents());
            type_builder
                .recursive_type_aliases()
                .lock()
                .unwrap()
                .extend(test.type_builder_recursive_aliases().iter().cloned());
            type_builder
                .recursive_classes()
                .lock()
                .unwrap()
                .extend(test.type_builder_recursive_classes().iter().cloned());

            return Ok(Some(type_builder));
        }

        let expr_fn = self.ir().find_expr_fn(function_name)?;
        let test = expr_fn.find_test(test_name).ok_or_else(|| {
            anyhow::anyhow!(
                "Test '{}' not found for expr function '{}'",
                test_name,
                function_name
            )
        })?;

        if test.item.1.elem.type_builder.entries.is_empty() {
            return Ok(None);
        }

        let type_builder = TypeBuilder::new();
        type_builder.add_entries(&test.item.1.elem.type_builder.entries);
        type_builder
            .recursive_type_aliases()
            .lock()
            .unwrap()
            .extend(
                test.item

View on GitHub (pinned to bd85ce9dee)