Fix AzureMachinePoolMachine controller test MSI error when run locally

Author: Cecile Robert-Michon

exp/controllers/azuremachinepoolmachine_controller_test.go

@@ -18,9 +18,12 @@ package controllers
 
 import (
 	"context"
+	"os"
 	"testing"
 	"time"
 
+	"github.com/Azure/go-autorest/autorest/azure/auth"
+
 	"github.com/golang/mock/gomock"
 	. "github.com/onsi/gomega"
 	corev1 "k8s.io/api/core/v1"
@@ -73,6 +76,10 @@ func TestAzureMachinePoolMachineReconciler_Reconcile(t *testing.T) {
 		},
 	}
 
+	os.Setenv(auth.ClientID, "fooClient")
+	os.Setenv(auth.ClientSecret, "fooSecret")
+	os.Setenv(auth.TenantID, "fooTenant")
+
 	for _, c := range cases {
 		t.Run(c.Name, func(t *testing.T) {
 			var (