ExUnit v1.3.3 ExUnit.CaptureLog View Source

Functionality to capture logs for testing.

Examples

defmodule AssertionTest do
  use ExUnit.Case

  import ExUnit.CaptureLog

  test "example" do
    assert capture_log(fn ->
      Logger.error "log msg"
    end) =~ "log msg"
  end

  test "check multiple captures concurrently" do
    fun = fn ->
      for msg <- ["hello", "hi"] do
        assert capture_log(fn -> Logger.error msg end) =~ msg
      end
      Logger.debug "testing"
    end
    assert capture_log(fun) =~ "hello"
    assert capture_log(fun) =~ "testing"
  end
end

Link to this section Summary

Functions

capture_log(opts \\ [], fun)

Captures Logger messages generated when evaluating fun

Link to this section Functions

capture_log(opts \\ [], fun)

capture_log(Keyword.t, (() -> any)) :: String.t

Captures Logger messages generated when evaluating fun.

Returns the binary which is the captured output.

This function mutes the :console backend and captures any log messages sent to Logger.

Note that when the async is set to true, the messages from another test might be captured.

It is possible to configure the level to capture with :level, which will set the capturing level for the duration of the capture, for instance, if the log level is set to :error any message with the lower level will be ignored. The default level is nil, which will capture all messages. The behaviour is undetermined if async tests change Logger level.

The format, metadata and colors can be configured with :format, :metadata and :colors respectively. These three options defaults to the :console backend configuration parameters.