# `PactEx.Log`
[🔗](https://github.com/arctarus/pact_ex/blob/v0.1.0/lib/pact_ex/log.ex#L1)

Configures where the native Pact library writes its logs.

The native library keeps one logger for the whole OS process. It can be set
up once, and it cannot be changed or removed afterwards. Call `init/1` once,
early (for example in `test/test_helper.exs`), before the first mock server
starts.

    PactEx.Log.init(level: :debug, sink: {:file, "tmp/pact.log"})

A `:stdout` or `:stderr` sink mixes Pact's output with your test output.
Prefer a file when you only need the logs to debug a failing contract.

Logs are never forwarded to Elixir's `Logger`.

# `level`

```elixir
@type level() :: :off | :error | :warn | :info | :debug | :trace
```

# `sink`

```elixir
@type sink() :: :stdout | :stderr | {:file, Path.t()}
```

# `init`

```elixir
@spec init(keyword()) ::
  :ok | {:error, :already_initialized} | {:error, PactEx.Error.t()}
```

Sets up the native logger.

Succeeds only once per OS process. After a logger is applied, a call whose
sink can be set up returns `{:error, :already_initialized}`, whatever its
options. A sink that fails to set up still returns its own error. Invalid
options still raise.

## Options

  * `:level` - the most verbose level to write: `:off`, `:error`, `:warn`,
    `:info`, `:debug` or `:trace`. Defaults to `:info`.
  * `:sink` - where to write: `:stdout`, `:stderr` or `{:file, path}`.
    Defaults to `:stdout`. A file sink appends to the file, creates it and
    any missing parent directories, and is opened even when the logger turns
    out to be initialised already. The path must not be blank or start or
    end with whitespace, because the native library would trim it.

Returns:

  * `:ok` - the logger is set up.
  * `{:error, :already_initialized}` - a logger is already set up in this
    OS process.
  * `{:error, %PactEx.Error{}}` - the sink could not be set up. Code `-6`
    means the log file could not be opened. Code `-100` means the path
    contains a NUL byte. No logger is applied by the failed call, so you can
    call `init/1` again with a different sink, as long as no logger was
    applied earlier.

Raises `ArgumentError` for an unknown option, an unknown level, or a sink
that is not `:stdout`, `:stderr` or `{:file, path}` with a UTF-8 path that is
not blank and has no leading or trailing whitespace.

---

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