terraform: ResourceDiff tests

terraform/diff.go

@@ -98,6 +98,10 @@ type ResourceAttrDiff struct {
 // RequiresNew returns true if the diff requires the creation of a new
 // resource (implying the destruction of the old).
 func (d *ResourceDiff) RequiresNew() bool {
+	if d == nil {
+		return false
+	}
+
 	for _, rd := range d.Attributes {
 		if rd.RequiresNew {
 			return true

terraform/diff_test.go

@@ -35,6 +35,32 @@ func TestDiff_String(t *testing.T) {
 	}
 }
 
+func TestResourceDiff_RequiresNew(t *testing.T) {
+	rd := &ResourceDiff{
+		Attributes: map[string]*ResourceAttrDiff{
+			"foo": &ResourceAttrDiff{},
+		},
+	}
+
+	if rd.RequiresNew() {
+		t.Fatal("should not require new")
+	}
+
+	rd.Attributes["foo"].RequiresNew = true
+
+	if !rd.RequiresNew() {
+		t.Fatal("should require new")
+	}
+}
+
+func TestResourceDiff_RequiresNew_nil(t *testing.T) {
+	var rd *ResourceDiff
+
+	if rd.RequiresNew() {
+		t.Fatal("should not require new")
+	}
+}
+
 const diffStrBasic = `
 CREATE: nodeA
   bar:     "foo" => "<computed>"