terraform: Diff.Empty

terraform/diff.go

@@ -69,6 +69,21 @@ func (d *Diff) init() {
 	})
 }
 
+// Empty returns true if the diff has no changes.
+func (d *Diff) Empty() bool {
+	if len(d.Resources) == 0 {
+		return true
+	}
+
+	for _, rd := range d.Resources {
+		if len(rd.Attributes) > 0 {
+			return false
+		}
+	}
+
+	return true
+}
+
 // String outputs the diff in a long but command-line friendly output
 // format that users can read to quickly inspect a diff.
 func (d *Diff) String() string {

terraform/diff_test.go

@@ -7,6 +7,32 @@ import (
 	"testing"
 )
 
+func TestDiff_Empty(t *testing.T) {
+	diff := new(Diff)
+	if !diff.Empty() {
+		t.Fatal("should be empty")
+	}
+
+	diff.Resources = map[string]*ResourceDiff{
+		"nodeA": &ResourceDiff{},
+	}
+
+	if !diff.Empty() {
+		t.Fatal("should be empty")
+	}
+
+	diff.Resources["nodeA"].Attributes = map[string]*ResourceAttrDiff{
+		"foo": &ResourceAttrDiff{
+			Old: "foo",
+			New: "bar",
+		},
+	}
+
+	if diff.Empty() {
+		t.Fatal("should not be empty")
+	}
+}
+
 func TestDiff_String(t *testing.T) {
 	diff := &Diff{
 		Resources: map[string]*ResourceDiff{