View Source ExUnit.CaptureLog (ExUnit v1.17.2)
Functionality to capture logs for testing.
Examples
defmodule AssertionTest do
use ExUnit.Case
import ExUnit.CaptureLog
require Logger
test "example" do
{result, log} =
with_log(fn ->
Logger.error("log msg")
2 + 2
end)
assert result == 4
assert log =~ "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
Summary
Functions
Captures Logger messages generated when evaluating fun
.
Invokes the given fun
and returns the result and captured log.
Functions
Captures Logger messages generated when evaluating fun
.
Returns the binary which is the captured output. The captured log
messages will be formatted using Logger.default_formatter/1
. Any
option, besides the :level
, will be forwarded as an override to
the default formatter.
This function mutes the default logger handler and captures any log messages sent to Logger from the calling processes. It is possible to ensure explicit log messages from other processes are captured by waiting for their exit or monitor signal.
Note that when the async
is set to true
on use ExUnit.Case
,
messages from other tests might be captured. This is OK as long
you consider such cases in your assertions, typically by using
the =~/2
operator to perform partial matches.
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
, then
any message with the lower level will be ignored.
The default level is nil
, which will capture all messages.
Note this setting does not override the overall Logger.level/0
value.
Therefore, if Logger.level/0
is set to a higher level than the one
configured in this function, no message will be captured.
The behaviour is undetermined if async tests change Logger level.
To get the result of the evaluation along with the captured log,
use with_log/2
.
Invokes the given fun
and returns the result and captured log.
It accepts the same arguments and options as capture_log/2
.
Examples
{result, log} =
with_log(fn ->
Logger.error("log msg")
2 + 2
end)
assert result == 4
assert log =~ "log msg"