From de22374751a742bafabd893391c94956d5104bb5 Mon Sep 17 00:00:00 2001
From: Vardan Torosyan <vardants@gmail.com>
Date: Wed, 16 Dec 2020 16:12:02 +0100
Subject: [PATCH] Usage Stats: Introduce an interface for usage stats service
 (#29882)

Adding an interface type for usage stats service allows us to not depend on the implementation outside of the package, for example when testing we can easily mock the service
---
 pkg/infra/usagestats/service.go          |  6 ++++++
 pkg/infra/usagestats/usage_stats_test.go | 11 +++++++++++
 2 files changed, 17 insertions(+)

diff --git a/pkg/infra/usagestats/service.go b/pkg/infra/usagestats/service.go
index 9dc3be51fb2..6c82e1e714f 100644
--- a/pkg/infra/usagestats/service.go
+++ b/pkg/infra/usagestats/service.go
@@ -21,6 +21,12 @@ func init() {
 	registry.RegisterService(&UsageStatsService{})
 }
 
+type UsageStats interface {
+	GetUsageReport() (UsageReport, error)
+
+	RegisterMetric(name string, fn MetricFunc)
+}
+
 type MetricFunc func() (interface{}, error)
 
 type UsageStatsService struct {
diff --git a/pkg/infra/usagestats/usage_stats_test.go b/pkg/infra/usagestats/usage_stats_test.go
index d779ad4b159..356fd6b108e 100644
--- a/pkg/infra/usagestats/usage_stats_test.go
+++ b/pkg/infra/usagestats/usage_stats_test.go
@@ -25,6 +25,17 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+// This is to ensure that the interface contract is held by the implementation
+func Test_InterfaceContractValidity(t *testing.T) {
+	newUsageStats := func() UsageStats {
+		return &UsageStatsService{}
+	}
+	v, ok := newUsageStats().(*UsageStatsService)
+
+	assert.NotNil(t, v)
+	assert.True(t, ok)
+}
+
 func TestMetrics(t *testing.T) {
 	t.Run("When sending usage stats", func(t *testing.T) {
 		uss := &UsageStatsService{