How-to-write-unit-test.md

How to write a unit test

Test Framework

If you need some test instructions, such as assert, require, mock and suite, you can use this package to assist you in testing: github.com/stretchr/testify. More usage methods can be found in Instructions.

test tools

From the plugin development and Log Printing, you can see that the ilogtail.Context interface contains the meta configuration information of iLogtail, so Mock Context and Mock Collector are provided for unit testing.

import (
 "github.com/stretchr/testify/assert"

 "github.com/alibaba/ilogtail/pkg/pipeline"
 "github.com/alibaba/ilogtail/plugins/test"
 "github.com/alibaba/ilogtail/plugins/test/mock"

 "testing"
)

func TestInputSystem_CollectOpenFD(t *testing.T) {
 cxt := mock.NewEmptyContext("project", "store", "config")
 p := pipeline.MetricInputs["metric_system_v2"]().(*InputSystem)
 _, err := p.Init(cxt)
 assert.NoError(t, err, "cannot init the mock process plugin: %v", err)
 c := &test.MockMetricCollector{}
 p.CollectOpenFD(c)
 assert.Equal(t, 2, len(c.Logs))
 m := make(map[string]string)
 for _, log := range c.Logs {
  for _, content := range log.Contents {
   if content.Key == "__name__" {
    m[content.Value] = "exist"
   }
  }
 }
 assert.NotEqual(t, "", m["fd_allocated"])
 assert.NotEqual(t, "", m["fd_max"])
}

Test plugin behavior

If you need logs to verify the specific behavior of the plugin, you can refer to the part named "Read log content[Advanced]".