func TestFetchMetrics(t *testing.T) {
	port := "27017"
	for _, tag := range []string{"3.0", "3.2", "latest"} {
		opts := createContainerOptions(tag, port)
		err := invokeFunctionWithContainer(func() {
			var mongodb MongoDBPlugin = MongoDBPlugin{URL: "localhost:" + port}
			_, err := mongodb.FetchMetrics()
			if err != nil {
				t.Errorf("Error: %s", err.Error())
			}
		}, opts)
		if err != nil {
			t.Errorf("Error: %s", err.Error())
		}
	}
}
These tests do not check logger's output yet.
You can see logger's output by `go test -v`
package mpmongodb
import (
	"fmt"
	"strings"
	"testing"
	"github.com/fsouza/go-dockerclient"
)