litellm/litellm-rust/AGENTS.md

Rust workspace rules

Test placement

• Never create a tests.rs (or test.rs) file under src/, and never #[path = "tests.rs"] mod tests;
• A test that reaches private items lives inline, in a #[cfg(test)] mod tests { ... } at the bottom of the file that owns those items
• A test that only uses the crate's public API lives in crates/<crate>/tests/<subject>.rs, next to src/
• Split a mixed test file along that line instead of widening visibility to move it
• A test for another crate's item belongs in that crate, not in a downstream one
• Never set autotests = false or hand-list [[test]] targets; every file directly under tests/ is discovered by cargo, and a shared helper goes in tests/<name>/mod.rs or tests/<subject>/support.rs so it is not picked up as a test crate of its own

Error definitions

• A crate's errors live in src/error.rs, defined with thiserror, and re-exported from lib.rs
• Default to one top-level Error enum per crate, with one variant per failure mode and a #[error(...)] message on each
• Wrap a lower-level error as a variant with #[from] or #[source] instead of flattening it to a string
• Exception: split into separate types when different functions fail in disjoint ways, especially when different callers see them. A shared enum would force every caller to match variants its function can never return
• Name a split type after what went wrong (a unit struct is fine for a single failure mode), not after the function that returns it