# `cache/null.ts`

## Purpose

`NullHibpCache<V>` is the always-miss adapter used by `HibpClient` when
the caller explicitly opts out of caching (`cache: null`). It satisfies
the `HibpCacheLike<V>` shape so the orchestrator code stays branch-free —
every cache call goes through the same interface, but the null adapter
makes every lookup a miss and every store a no-op.

## Features

- `get` always returns `undefined`.
- `set` is a no-op.
- `delete` always returns `false`.
- `size` is always `0`.
- Zero allocation per call — instances are stateless beyond the JS class
  identity.

## Usage: Basic Example

```ts
import { HibpClient, NullHibpCache } from "@suaveplan/hibp";

const client = new HibpClient({ cache: new NullHibpCache() });
```

## Usage: Advanced Example

```ts
import { HibpClient } from "@suaveplan/hibp";

// Shorthand: passing `null` resolves to NullHibpCache internally.
const client = new HibpClient({ cache: null });
```

## API Reference

- `new NullHibpCache<V>()` — generic, no options.
- All `HibpCacheLike<V>` methods present and conformant.

## Implementation Notes

Using a dedicated class instead of an inline conditional avoids a
property branch on every `HibpClient.checkPassword` call. It also keeps
the public type system honest: a `HibpCacheLike` is always a real cache,
never `undefined`. Callers who want caching disabled make that intention
explicit by constructing or asking for `NullHibpCache`. The class is
generic so consumers of typed cache values (e.g. `Breach[]` caches
layered on top of the package) still get the right type for their
`get()` returns when they inject a `NullHibpCache<Breach[]>` instead.
Tests benefit too — running `checkPassword` against a `NullHibpCache`
guarantees every call exercises the full fetch+parse path, with no
hidden cache hits hiding behaviour bugs.