Add test for collector Describe method

go.mod

@@ -3,7 +3,7 @@ module github.com/arunvelsriram/sftp-exporter
 go 1.14
 
 require (
-	github.com/golang/mock v1.4.3 // indirect
+	github.com/golang/mock v1.4.3
 	github.com/pkg/sftp v1.11.0
 	github.com/prometheus/client_golang v0.9.3
 	github.com/sirupsen/logrus v1.2.0

main.go

@@ -4,6 +4,7 @@ import "github.com/arunvelsriram/sftp-exporter/cmd"
 
 //go:generate mkdir -p pkg/internal/mocks
 //go:generate mockgen -source pkg/config/config.go -destination pkg/internal/mocks/config.go -package mocks
+//go:generate mockgen -source pkg/client/sftp_client.go -destination pkg/internal/mocks/sftp_client.go -package mocks
 func main() {
 	cmd.Execute()
 }

pkg/collector/sftp_collector.go

@@ -46,8 +46,11 @@ var (
 	)
 )
 
+type CreateClientFn func(config.Config) (client.SFTPClient, error)
+
 type SFTPCollector struct {
-	config config.Config
+	config         config.Config
+	createClientFn CreateClientFn
 }
 
 func (s SFTPCollector) Describe(ch chan<- *prometheus.Desc) {
@@ -59,7 +62,7 @@ func (s SFTPCollector) Describe(ch chan<- *prometheus.Desc) {
 }
 
 func (s SFTPCollector) Collect(ch chan<- prometheus.Metric) {
-	sftpClient, err := client.NewSFTPClient(s.config)
+	sftpClient, err := s.createClientFn(s.config)
 	if err != nil {
 		ch <- prometheus.MustNewConstMetric(up, prometheus.GaugeValue, 0)
 		log.WithFields(log.Fields{"event": "creating SFTP sftpClient"}).Error(err)
@@ -89,6 +92,6 @@ func (s SFTPCollector) Collect(ch chan<- prometheus.Metric) {
 	}
 }
 
-func NewSFTPCollector(cfg config.Config) prometheus.Collector {
-	return SFTPCollector{config: cfg}
+func NewSFTPCollector(cfg config.Config, fn CreateClientFn) prometheus.Collector {
+	return SFTPCollector{config: cfg, createClientFn: fn}
 }

pkg/collector/sftp_collector_test.go

@@ -0,0 +1,75 @@
+package collector
+
+import (
+	"testing"
+
+	"github.com/arunvelsriram/sftp-exporter/pkg/client"
+	"github.com/arunvelsriram/sftp-exporter/pkg/config"
+	"github.com/arunvelsriram/sftp-exporter/pkg/internal/mocks"
+	"github.com/golang/mock/gomock"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/stretchr/testify/suite"
+)
+
+type SFTPCollectorSuite struct {
+	suite.Suite
+	ctrl           *gomock.Controller
+	config         config.Config
+	sftpClient     client.SFTPClient
+	createClientFn CreateClientFn
+	collector      prometheus.Collector
+}
+
+func TestSFTPCollectorSuite(t *testing.T) {
+	suite.Run(t, new(SFTPCollectorSuite))
+}
+
+func (s *SFTPCollectorSuite) SetupTest() {
+	s.ctrl = gomock.NewController(s.T())
+	s.config = mocks.NewMockConfig(s.ctrl)
+	s.sftpClient = mocks.NewMockSFTPClient(s.ctrl)
+	fn := func(c config.Config) (client.SFTPClient, error) {
+		return s.sftpClient, nil
+	}
+	s.createClientFn = CreateClientFn(fn)
+	s.collector = NewSFTPCollector(s.config, s.createClientFn)
+}
+
+func (s *SFTPCollectorSuite) TearDownTest() {
+	s.ctrl.Finish()
+}
+
+func (s *SFTPCollectorSuite) TestSFTPCollectorDescribe() {
+	ch := make(chan *prometheus.Desc)
+	go s.collector.Describe(ch)
+
+	up := <-ch
+	s.Equal(
+		`Desc{fqName: "sftp_up", help: "Tells if exporter is able to connect to SFTP", constLabels: {}, variableLabels: []}`,
+		up.String(),
+	)
+
+	fsTotalSpace := <-ch
+	s.Equal(
+		`Desc{fqName: "sftp_filesystem_total_space_bytes", help: "Total space in the filesystem containing the path", constLabels: {}, variableLabels: [path]}`,
+		fsTotalSpace.String(),
+	)
+
+	fsFreeSpace := <-ch
+	s.Equal(
+		`Desc{fqName: "sftp_filesystem_free_space_bytes", help: "Free space in the filesystem containing the path", constLabels: {}, variableLabels: [path]}`,
+		fsFreeSpace.String(),
+	)
+
+	objectCount := <-ch
+	s.Equal(
+		`Desc{fqName: "sftp_objects_count_total", help: "Total number of objects in the path", constLabels: {}, variableLabels: [path]}`,
+		objectCount.String(),
+	)
+
+	objectSize := <-ch
+	s.Equal(
+		`Desc{fqName: "sftp_objects_size_total_bytes", help: "Total size of all objects in the path", constLabels: {}, variableLabels: [path]}`,
+		objectSize.String(),
+	)
+}

pkg/server/server.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"net/http"
 
+	"github.com/arunvelsriram/sftp-exporter/pkg/client"
 	"github.com/arunvelsriram/sftp-exporter/pkg/collector"
 	"github.com/arunvelsriram/sftp-exporter/pkg/config"
 	"github.com/prometheus/client_golang/prometheus"
@@ -12,7 +13,8 @@ import (
 )
 
 func Start(cfg config.Config) error {
-	sftpCollector := collector.NewSFTPCollector(cfg)
+	createClientFn := collector.CreateClientFn(client.NewSFTPClient)
+	sftpCollector := collector.NewSFTPCollector(cfg, createClientFn)
 	prometheus.MustRegister(sftpCollector)
 
 	r := http.NewServeMux()