terraform: add ResourceState.Taint

terraform/state.go

@@ -699,6 +699,19 @@ func (s *ResourceState) Equal(other *ResourceState) bool {
 	return true
 }
 
+// Taint takes the primary state and marks it as tainted. If there is no
+// primary state, this does nothing.
+func (r *ResourceState) Taint() {
+	// If there is no primary, nothing to do
+	if r.Primary == nil {
+		return
+	}
+
+	// Shuffle to the end of the taint list and set primary to nil
+	r.Tainted = append(r.Tainted, r.Primary)
+	r.Primary = nil
+}
+
 func (r *ResourceState) init() {
 	if r.Primary == nil {
 		r.Primary = &InstanceState{}
@@ -710,16 +723,24 @@ func (r *ResourceState) deepcopy() *ResourceState {
 	if r == nil {
 		return nil
 	}
+
 	n := &ResourceState{
 		Type:         r.Type,
-		Dependencies: make([]string, len(r.Dependencies)),
+		Dependencies: nil,
 		Primary:      r.Primary.deepcopy(),
-		Tainted:      make([]*InstanceState, 0, len(r.Tainted)),
+		Tainted:      nil,
 	}
-	copy(n.Dependencies, r.Dependencies)
-	for _, inst := range r.Tainted {
-		n.Tainted = append(n.Tainted, inst.deepcopy())
+	if r.Dependencies != nil {
+		n.Dependencies = make([]string, len(r.Dependencies))
+		copy(n.Dependencies, r.Dependencies)
 	}
+	if r.Tainted != nil {
+		n.Tainted = make([]*InstanceState, 0, len(r.Tainted))
+		for _, inst := range r.Tainted {
+			n.Tainted = append(n.Tainted, inst.deepcopy())
+		}
+	}
+
 	return n
 }
 

terraform/state_test.go

@@ -275,6 +275,53 @@ func TestResourceStateEqual(t *testing.T) {
 	}
 }
 
+func TestResourceStateTaint(t *testing.T) {
+	cases := map[string]struct {
+		Input  *ResourceState
+		Output *ResourceState
+	}{
+		"no primary": {
+			&ResourceState{},
+			&ResourceState{},
+		},
+
+		"primary, no tainted": {
+			&ResourceState{
+				Primary: &InstanceState{ID: "foo"},
+			},
+			&ResourceState{
+				Tainted: []*InstanceState{
+					&InstanceState{ID: "foo"},
+				},
+			},
+		},
+
+		"primary, with tainted": {
+			&ResourceState{
+				Primary: &InstanceState{ID: "foo"},
+				Tainted: []*InstanceState{
+					&InstanceState{ID: "bar"},
+				},
+			},
+			&ResourceState{
+				Tainted: []*InstanceState{
+					&InstanceState{ID: "bar"},
+					&InstanceState{ID: "foo"},
+				},
+			},
+		},
+	}
+
+	for k, tc := range cases {
+		tc.Input.Taint()
+		if !reflect.DeepEqual(tc.Input, tc.Output) {
+			t.Fatalf(
+				"Failure: %s\n\nExpected: %#v\n\nGot: %#v",
+				k, tc.Output, tc.Input)
+		}
+	}
+}
+
 func TestInstanceStateEqual(t *testing.T) {
 	cases := []struct {
 		Result   bool