dbt-labs/dbt-core · error

mock config for adapter type {:?}

Error message

mock config for adapter type {:?}

What it means

In the mock/test adapter factory, only a fixed set of adapter types (DuckDB, Snowflake, Postgres, etc.) have mock configurations; for BigQuery, Redshift, Spark, and Databricks an empty config is returned, but for every other adapter type the factory panics with `unimplemented!("mock config for adapter type {:?}")`. This is a test-infrastructure limitation: the mock engine cannot be constructed for adapters no one has configured yet.

Source

Thrown at crates/dbt-adapter/src/adapter/adapter_impl.rs:6036

            DuckDB => {
                let attach = YmlValue::Sequence(
                    vec![YmlValue::Mapping(
                        Mapping::from_iter([
                            ("path".into(), "md:some_db".into()),
                            ("is_ducklake".into(), true.into()),
                        ]),
                        Default::default(),
                    )],
                    Default::default(),
                );
                Mapping::from_iter([
                    ("path".into(), "md:my_db".into()),
                    ("is_ducklake".into(), true.into()),
                    ("attach".into(), attach),
                ])
            }
            Bigquery | Redshift | Spark | Databricks => Mapping::new(),
            _ => unimplemented!("mock config for adapter type {:?}", adapter_type),
        };
        build_engine(adapter_type, config)
    }

    fn build_engine(adapter_type: AdapterType, config: Mapping) -> Arc<dyn AdapterEngine> {
        build_engine_with_behavior(adapter_type, config, BTreeMap::new())
    }

    fn build_engine_with_behavior(
        adapter_type: AdapterType,
        config: Mapping,
        behavior_flag_overrides: BTreeMap<String, bool>,
    ) -> Arc<dyn AdapterEngine> {
        let auth = auth_for_backend(backend_of(adapter_type));
        let resolved_quoting = match adapter_type {
            Snowflake => SNOWFLAKE_RESOLVED_QUOTING,
            _ => DEFAULT_RESOLVED_QUOTING,
        };

View on GitHub (pinned to 0267ce9170)

Solutions

1. Add a mock config arm for your adapter type in the factory (even an empty `Mapping::new()` like BigQuery/Redshift/Spark/Databricks if no special settings are needed).
2. Switch the test to a supported adapter type (e.g. DuckDB or Snowflake) if the adapter specifics are irrelevant to what you're testing.
3. If the adapter genuinely can't be mocked, gate the test with an ignore/skip for that adapter type.

Example fix

// before
_ => unimplemented!("mock config for adapter type {:?}", adapter_type),
// after
Athena | Trino => Mapping::new(),
_ => unimplemented!("mock config for adapter type {:?}", adapter_type),

// Rust, before requesting a mock
const MOCKABLE: &[AdapterType] = &[
    AdapterType::DuckDB, AdapterType::Snowflake, AdapterType::Postgres,
    AdapterType::Bigquery, AdapterType::Redshift, AdapterType::Spark, AdapterType::Databricks,
];
assert!(MOCKABLE.contains(&adapter_type), "no mock config for {adapter_type:?}");

fn mockable(t: AdapterType) -> bool {
    matches!(t,
        AdapterType::DuckDB | AdapterType::Snowflake | AdapterType::Postgres |
        AdapterType::Bigquery | AdapterType::Redshift | AdapterType::Spark | AdapterType::Databricks)
}

// Panics are fatal in tests; validate the adapter type when building the harness
let engine = if mockable(adapter_type) { build_mock(adapter_type) } else { panic!("add mock config for {adapter_type:?}") };

When it happens

Trigger: Requesting a mock adapter engine via `mock_config`/`build_engine` for an adapter type outside the handled set (not DuckDB/Postgres/Snowflake or the explicitly empty-config BigQuery/Redshift/Spark/Databricks set) — typically in unit tests or record/replay harnesses.

Common situations: Writing a new test that instantiates a mock adapter for a less common warehouse (e.g. Athena, Trino, Oracle, ClickHouse); adding a new AdapterType variant and forgetting to extend the mock factory; record-replay tooling encountering an unmocked adapter.

Related errors

• query addition to connection in MockAdapter
• type conversion from table column in MockAdapter
• Trino
• Datafusion
• Dremio

AI-assisted analysis of dbt-labs/dbt-core@0267ce9170 (2026-09-07). Data as JSON: /api/errors/75fa98555113eb16. Report an issue: GitHub.