chore: adds tests (#2845)

internal/docker/stats_collector_test.go

@@ -0,0 +1,49 @@
+package docker
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+)
+
+func TestSubscribe(t *testing.T) {
+	client := new(mockedClient)
+	client.On("ListContainers").Return([]Container{
+		{
+			ID:    "1234",
+			Name:  "test",
+			State: "running",
+		},
+	}, nil)
+	client.On("Events", mock.Anything, mock.AnythingOfType("chan<- docker.ContainerEvent")).Return(make(chan error))
+	client.On("ContainerStats", mock.Anything, mock.Anything, mock.AnythingOfType("chan<- docker.ContainerStat")).
+		Return(nil).
+		Run(func(args mock.Arguments) {
+			stats := args.Get(2).(chan<- ContainerStat)
+			stats <- ContainerStat{
+				ID: "1234",
+			}
+		})
+
+	ctx, cancel := context.WithCancel(context.Background())
+	t.Cleanup(cancel)
+
+	collector := NewStatsCollector(client)
+	stats := make(chan ContainerStat)
+
+	collector.Subscribe(ctx, stats)
+
+	_, ok := collector.subscribers.Load(ctx)
+	assert.True(t, ok)
+
+	go collector.Start(ctx)
+
+	<-stats
+
+	_, ok = collector.cancelers.Load("1234")
+	assert.True(t, ok, "canceler should be stored")
+
+	assert.False(t, collector.Start(ctx), "second start should return false")
+}