# `Soundcheck.Check.Warning.UndefinedStream`
[🔗](https://github.com/leonqadirie/soundcheck/blob/v0.1.0/lib/soundcheck/check/warning/undefined_stream.ex#L1)

## Basics

> #### This check is disabled by default. {: .neutral}
>
> [Learn how to enable it](`e:credo:config_file.html#checks`) via `.credo.exs`.

This check has a base priority of `high` and works with any version of Elixir.

## Explanation

Flags stream names a LiveView or LiveComponent uses but never
defines. `@streams` holds only the streams that `stream/4` or
`stream_async/4` created, so a template reading `@streams.post` when
the module streams `:posts` raises `KeyError` on render, and
`stream_insert/4`, `stream_delete/3`, or `stream_delete_by_dom_id/3`
on an unknown name raises `ArgumentError`.

Before:

    def mount(_params, _session, socket),
      do: {:ok, stream(socket, :posts, Blog.list_posts())}

    <div id="posts" phx-update="stream">
      <div :for={{id, post} <- @streams.post} id={id}>{post.title}</div>
    </div>

After:

    <div :for={{id, post} <- @streams.posts} id={id}>{post.title}</div>

Definitions are `stream/3,4`, `stream_async/3,4`, and
`stream_configure/3` calls with a literal atom name in the module's
own functions and in the project functions it calls, through remote
calls and imports at any depth. Reads come from its `render/1`
template, colocated or inline. The check skips a module when it and
those functions define no stream, when any of them names one
dynamically, or when it passes its socket to a function outside the
project and Phoenix, since that function may define streams the
check cannot see.

Confidence: medium. Tier: syntactic (works without compiling).

## Check-Specific Parameters

Use the following parameters to configure this check:

### `:excluded_paths`

  Paths to skip (atoms, binaries as path segments, or regexes).

*This parameter defaults to* `[~r/\/test\//, "test"]`.

### `:strict`

  Unused.

*This parameter defaults to* `false`.

## General Parameters

Like with all checks, [general params](`e:credo:check_params.html`) can be applied.

Parameters can be configured via the [`.credo.exs` config file](`e:credo:config_file.html`).

---

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