Update the GetAllByGroupName method

1. Why is this change necessary?
Because if an error occurs there is no way to handle it in the log.Fatal
handle of the error

2. How does it address the issue?
Returns the error to the caller, so is easy to handle the error

3. What side effects does this change have?
None in the use of the project, but does in the testing. Accordingly
with: golang/go#31859 we need a
`testing.Init()` in the `init` function of the testing file

4. Test
`make test ARGS="-client edae63d9-3f66-47de-860d-8b23b55c8544 -tenant c8cd0425-e7b7-4f3d-9215-7e5fa3f439e8 -secret 1016e85d-3f23-4953-97a1-2cec4dccb0a4"`

Makefile

@@ -12,12 +12,12 @@ go-generate:
 
 go-test:
 	@echo "  >  Testing"
-	go test -race .
+	go test -race . $(ARGS)
 
 go-test-clean:
 	@echo "  >  Cleaning test"
 	@go clean -testcache
 
 go-test-verbose:
 	@echo "  >  Testing verbosely"
-	go test -v . -race
+	go test -v -race . $(ARGS)

generate/main.tpl

@@ -5,7 +5,6 @@ package azure_resources
 
 import (
 	"context"
-	"log"
 
 	"github.com/Azure/azure-sdk-for-go/profiles/latest/resources/mgmt/resources"
 	"github.com/Azure/go-autorest/autorest"
@@ -15,20 +14,20 @@ import (
 
 var authorizer autorest.Authorizer
 
-type resource interface {
+type Resource interface {
 	GetProperties() ([]byte, error)
 }
 
-func GetAllByGroupName(subscriptionID, groupName string) []resource {
+func GetAllByGroupName(subscriptionID, groupName string) ([]Resource, error) {
 	client := resources.NewClient(subscriptionID)
 	client.Authorizer = authorizer
 
 	results, err := client.ListByResourceGroup(context.Background(), groupName, "", "", nil)
 	if err != nil {
-		log.Fatalln(err)
+		return nil, err
 	}
 
-	var resources []resource
+	var resources []Resource
 
 	for _, resource := range results.Values() {
 		switch *resource.Type {
@@ -45,7 +44,7 @@ func GetAllByGroupName(subscriptionID, groupName string) []resource {
 		}
 	}
 
-	return resources
+	return resources, nil
 }
 
 func SetAuthorizer(tenantID, clientID, clientSecret string) error {

main_test.go

@@ -1,14 +1,38 @@
 package azure_resources
 
-import "testing"
+import (
+	"flag"
+	"testing"
+)
+
+var (
+	clientID     string
+	clientSecret string
+	tenantID     string
+)
+
+func init() {
+	testing.Init()
+	flag.StringVar(&clientID, "client", "", "client to make the petition")
+	flag.StringVar(&clientSecret, "secret", "", "secret to make the petition")
+	flag.StringVar(&tenantID, "tenant", "", "tenant to make the petition")
+	flag.Parse()
+}
 
 func TestGetAllByGroupName(t *testing.T) {
 	const (
 		subscriptionID = "72166d64-f454-46c1-a2f7-e84b57df44b8"
-		groupName      = "azure-test"
+		groupName      = "terraform-resources"
 	)
 
-	resources := GetAllByGroupName(subscriptionID, groupName)
+	if err := SetAuthorizer(tenantID, clientID, clientSecret); err != nil {
+		t.Error(err)
+	}
+
+	resources, err := GetAllByGroupName(subscriptionID, groupName)
+	if err != nil {
+		t.Error(err)
+	}
 
 	for _, r := range resources {
 		props, err := r.GetProperties()