facebook/relay · error

interface B not found

Error message

interface B not found

What it means

Panic from `.expect("interface B not found")` in `test_extensions_print_after_definitions` (compiler/crates/schema-set/src/build_schema_document.rs:943). The test builds a SchemaSet containing `extend type A implements B` plus `interface B`, prints it with `set.to_sdl_definition()`, then searches the printed SDL for the substring `interface B`. The panic means the printed SDL contains no `interface B` definition at all — the printer dropped the interface, printed it under a different name/keyword, or the schema build failed to retain it.

Source

Thrown at compiler/crates/schema-set/src/build_schema_document.rs:943

    #[test]
    fn test_extensions_print_after_definitions() {
        let doc = parse_schema_document(
            indoc! {r#"
                extend type A implements B {
                  id: ID
                }

                interface B {
                  id: ID
                }
            "#},
            SourceLocationKey::generated(),
        )
        .unwrap();
        let set = SchemaSet::from_schema_documents_with_extensions(&[], &[doc]).unwrap();
        let sdl = format!("{}", set.to_sdl_definition());

        let interface_pos = sdl.find("interface B").expect("interface B not found");
        let extension_pos = sdl.find("extend type A").expect("extend type A not found");
        assert!(
            interface_pos < extension_pos,
            "Definitions should print before extensions: {}",
            sdl,
        );
    }

    #[test]
    fn test_object_fields_sorted_alphabetically() {
        let sdl = schema_sdl(indoc! {r#"
            type Foo {
              zebra: String
              apple: Int
              mango: Boolean
            }
        "#});
        // Fields should be sorted alphabetically

View on GitHub (pinned to 668b1b85e0)

Solutions

1. Print/debug the SDL string on failure (the adjacent assert already embeds `{}` — temporarily print `sdl` before `.find`) and check how `interface B` is actually rendered (maybe `interface B implements` or different spacing).
2. Verify the document passed to `from_schema_documents_with_extensions` still declares `interface B` and that the set build `.unwrap()` succeeded.
3. Inspect `to_sdl_definition`'s printer to confirm interfaces are emitted as base definitions before extensions; fix the printer if it drops or reorders them.
4. If rendering changed legitimately (e.g. keyword/spacing), update the test's search string accordingly.

Example fix

// before
let interface_pos = sdl.find("interface B").expect("interface B not found");
// after
let interface_pos = sdl
    .find("interface B")
    .unwrap_or_else(|| panic!("interface B not found in SDL:\n{}", sdl));

// Validate the set retains the interface before printing:
let sdl = format!("{}", set.to_sdl_definition());
assert!(sdl.contains("interface B"), "SDL missing interface B:\n{}", sdl);

fn prints_interface(sdl: &str, name: &str) -> bool {
    sdl.contains(&format!("interface {}", name))
}

// Prefer explicit failure with context over a bare expect:
let interface_pos = match sdl.find("interface B") {
    Some(p) => p,
    None => panic!("interface B not found in printed SDL:\n{}", sdl),
};

When it happens

Trigger: Calling `SchemaSet::from_schema_documents_with_extensions` with a document containing an `interface B` definition, then calling `to_sdl_definition()` and finding that the interface definition is absent from the output string (e.g. interfaces are only emitted when implemented-and-registered, or the printer skips unextended interfaces).

Common situations: A change in the SDL printer's emission order or filtering rules that drops interface definitions; building the set only from extension documents without registering base definitions; the interface renamed in the test input while the assertion still searches for the old string.

Related errors

• Expected docblocks to only expose object and scalar definiti
• Node.search exists
• extend type A not found
• apple not found
• mango not found

AI-assisted analysis of facebook/relay@668b1b85e0 (2026-09-02). Data as JSON: /api/errors/526d04d19d55354f. Report an issue: GitHub.