Stub metadata service for builder tests

builder/azure/chroot/builder_test.go

@@ -53,18 +53,20 @@ func TestBuilder_Prepare(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			b := &Builder{}
+			withMetadataStub(func() {
+				b := &Builder{}
 
-			_, _, err := b.Prepare(tt.config)
+				_, _, err := b.Prepare(tt.config)
 
-			if (err != nil) != tt.wantErr {
-				t.Errorf("Builder.Prepare() error = %v, wantErr %v", err, tt.wantErr)
-				return
-			}
+				if (err != nil) != tt.wantErr {
+					t.Errorf("Builder.Prepare() error = %v, wantErr %v", err, tt.wantErr)
+					return
+				}
 
-			if tt.validate != nil {
-				tt.validate(b.config)
-			}
+				if tt.validate != nil {
+					tt.validate(b.config)
+				}
+			})
 		})
 	}
 }

builder/azure/chroot/metadatastub_test.go

@@ -0,0 +1,18 @@
+package chroot
+
+import "github.com/hashicorp/packer/builder/azure/common/client"
+
+func withMetadataStub(f func()) {
+	mdc := client.DefaultMetadataClient
+	defer func() { client.DefaultMetadataClient = mdc }()
+	client.DefaultMetadataClient = client.MetadataClientStub{
+		ComputeInfo: client.ComputeInfo{
+			SubscriptionID:    "testSubscriptionID",
+			ResourceGroupName: "testResourceGroup",
+			Name:              "testVM",
+			Location:          "testLocation",
+		},
+	}
+
+	f()
+}

builder/azure/common/client/metadata.go

@@ -12,11 +12,22 @@ import (
 // DefaultMetadataClient is the default instance metadata client for Azure. Replace this variable for testing purposes only
 var DefaultMetadataClient = NewMetadataClient()
 
-// MetadataClient holds methods that Packer uses to get information about the current VM
+// MetadataClientAPI holds methods that Packer uses to get information about the current VM
 type MetadataClientAPI interface {
 	GetComputeInfo() (*ComputeInfo, error)
 }
 
+// MetadataClientStub is an easy way to put a test hook in DefaultMetadataClient
+type MetadataClientStub struct {
+	ComputeInfo
+}
+
+//GetComputeInfo implements MetadataClientAPI
+func (s MetadataClientStub) GetComputeInfo() (*ComputeInfo, error) {
+	return &s.ComputeInfo, nil
+}
+
+// ComputeInfo defines the Azure VM metadata that is used in Packer
 type ComputeInfo struct {
 	Name              string
 	ResourceGroupName string