# `Nous.Memory.Store.Conformance`
[🔗](https://github.com/nyo16/nous/blob/v0.17.1/lib/nous/memory/store/conformance.ex#L1)

Contract-conformance tests for a `Nous.Memory.Store` implementation.

This is a **test-time kit**: it ships in `lib/` so that a backend implemented
outside Nous can hold itself to the same battery Nous runs against its own
stores. `use` it in a test file with your store module and its init opts:

    defmodule MyApp.Memory.Store.TantivyConformanceTest do
      use Nous.Memory.Store.Conformance,
        store: MyApp.Memory.Store.Tantivy,
        init_opts: [index_path: "/tmp/test_index"]
    end

That is the whole file — the macro generates the module's `use ExUnit.Case`, its
setup and every test. A backend that needs a native dependency can hide the
suite behind a tag so it only runs where the dep is installed:

    defmodule Nous.Memory.Store.SQLiteConformanceTest do
      use Nous.Memory.Store.Conformance,
        store: Nous.Memory.Store.SQLite,
        init_opts: [path: ":memory:"],
        tag: :sqlite
    end

## What it covers, and what it does not

Every REQUIRED callback of `Nous.Memory.Store`: the `store/2` → `fetch/2`
round-trip, `:not_found` on a missing id, `delete/2`, `update/3` (including the
`:not_found` case and that it bumps `updated_at`), `list/2` with and without
`:scope`, and `search_text/3`'s ranking, `:limit` and `:scope` handling.

It does NOT cover `search_vector/3`, which is optional and feature-detected
(`Nous.Memory.Store.ETS` does not implement it). It also cannot check score
*direction* — see the warning in `Nous.Memory.Store` about returning a
similarity rather than a distance, which no contract test can catch for you.

Passing this suite means your backend is substitutable, not that it is fast or
that its retrieval is any good.

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*Consult [api-reference.md](api-reference.md) for complete listing*