facet-rs / facet / 20107317130

58%

Build Type

push

github

Committed by fasterthanlime

Commit Message

fix: serialize/deserialize untagged unit variants as strings

Fixes #1228

Previously, untagged enums with unit variants would serialize to `null`
(matching serde behavior), making it impossible to distinguish between
different unit variants. This broke roundtripping for enums like:

```rust
#[facet(untagged)]
enum Alla {
    AE,
    AD,
}
```

Changes:
- JSON: Unit variants in untagged enums now serialize as variant name
  strings (e.g., "AE") instead of null
- JSON: Deserialization now accepts variant name strings for unit variants
- YAML: Same deserialization fix (serialization already used variant names)
- Tests: Updated to reflect new behavior and document divergence from serde

This intentionally diverges from serde's behavior because:
1. Serde's null serialization makes multiple unit variants indistinguishable
2. Facet's approach enables proper roundtripping
3. Behavior is now consistent between tagged and untagged enums with
   unit variants

Breaking change: Code that relied on untagged unit variants serializing
to null will need to be updated. However, this previous behavior was
arguably broken as it prevented distinguishing between variants.

Run Details

13 of 17 new or added lines in 3 files covered. (76.47%)

27 existing lines in 1 file now uncovered.

27117 of 46296 relevant lines covered (58.57%)

616.11 hits per line