helper/schema: More CustomizeDiff test cases

Added a few more test cases for CustomizeDiff, caught another error in
the process. I think this is ready for review now, and possibly some
real-world testing of the waters by way of porting some resources that
would benefit from the feature.

helper/schema/schema.go

@@ -451,7 +451,7 @@ func (m schemaMap) Diff(
 		}
 
 		// Re-run customization
-		if customizeFunc != nil {
+		if !result2.Destroy && !result2.DestroyTainted && customizeFunc != nil {
 			mc := m.DeepCopy()
 			rd := newResourceDiff(mc, c, d.state, result2)
 			if err := customizeFunc(rd, meta); err != nil {

helper/schema/schema_test.go

@@ -2,6 +2,7 @@ package schema
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"os"
 	"reflect"
@@ -2826,7 +2827,46 @@ func TestSchemaMap_Diff(t *testing.T) {
 		},
 
 		{
-			Name: "overridden diff with a CustomizeDiff function",
+			Name: "overridden diff with a CustomizeDiff function, ForceNew not in schema",
+			Schema: map[string]*Schema{
+				"availability_zone": &Schema{
+					Type:     TypeString,
+					Optional: true,
+					Computed: true,
+				},
+			},
+
+			State: nil,
+
+			Config: map[string]interface{}{
+				"availability_zone": "foo",
+			},
+
+			CustomizeDiff: func(d *ResourceDiff, meta interface{}) error {
+				if err := d.SetNew("availability_zone", "bar"); err != nil {
+					return err
+				}
+				if err := d.ForceNew("availability_zone"); err != nil {
+					return err
+				}
+				return nil
+			},
+
+			Diff: &terraform.InstanceDiff{
+				Attributes: map[string]*terraform.ResourceAttrDiff{
+					"availability_zone": &terraform.ResourceAttrDiff{
+						Old:         "",
+						New:         "bar",
+						RequiresNew: true,
+					},
+				},
+			},
+
+			Err: false,
+		},
+
+		{
+			Name: "overridden diff with a CustomizeDiff function, ForceNew in schema",
 			Schema: map[string]*Schema{
 				"availability_zone": &Schema{
 					Type:     TypeString,
@@ -2861,6 +2901,215 @@ func TestSchemaMap_Diff(t *testing.T) {
 
 			Err: false,
 		},
+
+		{
+			Name: "required field with computed diff added with CustomizeDiff function",
+			Schema: map[string]*Schema{
+				"ami_id": &Schema{
+					Type:     TypeString,
+					Required: true,
+				},
+				"instance_id": &Schema{
+					Type:     TypeString,
+					Computed: true,
+				},
+			},
+
+			State: nil,
+
+			Config: map[string]interface{}{
+				"ami_id": "foo",
+			},
+
+			CustomizeDiff: func(d *ResourceDiff, meta interface{}) error {
+				if err := d.SetNew("instance_id", "bar"); err != nil {
+					return err
+				}
+				return nil
+			},
+
+			Diff: &terraform.InstanceDiff{
+				Attributes: map[string]*terraform.ResourceAttrDiff{
+					"ami_id": &terraform.ResourceAttrDiff{
+						Old: "",
+						New: "foo",
+					},
+					"instance_id": &terraform.ResourceAttrDiff{
+						Old: "",
+						New: "bar",
+					},
+				},
+			},
+
+			Err: false,
+		},
+
+		{
+			Name: "Set ForceNew only marks the changing element as ForceNew - CustomizeDiffFunc edition",
+			Schema: map[string]*Schema{
+				"ports": &Schema{
+					Type:     TypeSet,
+					Optional: true,
+					Computed: true,
+					Elem:     &Schema{Type: TypeInt},
+					Set: func(a interface{}) int {
+						return a.(int)
+					},
+				},
+			},
+
+			State: &terraform.InstanceState{
+				Attributes: map[string]string{
+					"ports.#": "3",
+					"ports.1": "1",
+					"ports.2": "2",
+					"ports.4": "4",
+				},
+			},
+
+			Config: map[string]interface{}{
+				"ports": []interface{}{5, 2, 6},
+			},
+
+			CustomizeDiff: func(d *ResourceDiff, meta interface{}) error {
+				if err := d.SetNew("ports", []interface{}{5, 2, 1}); err != nil {
+					return err
+				}
+				if err := d.ForceNew("ports"); err != nil {
+					return err
+				}
+				return nil
+			},
+
+			Diff: &terraform.InstanceDiff{
+				Attributes: map[string]*terraform.ResourceAttrDiff{
+					"ports.#": &terraform.ResourceAttrDiff{
+						Old: "3",
+						New: "3",
+					},
+					"ports.1": &terraform.ResourceAttrDiff{
+						Old: "1",
+						New: "1",
+					},
+					"ports.2": &terraform.ResourceAttrDiff{
+						Old: "2",
+						New: "2",
+					},
+					"ports.5": &terraform.ResourceAttrDiff{
+						Old:         "",
+						New:         "5",
+						RequiresNew: true,
+					},
+					"ports.4": &terraform.ResourceAttrDiff{
+						Old:         "4",
+						New:         "0",
+						NewRemoved:  true,
+						RequiresNew: true,
+					},
+				},
+			},
+		},
+
+		{
+			Name:   "tainted resource does not run CustomizeDiffFunc",
+			Schema: map[string]*Schema{},
+
+			State: &terraform.InstanceState{
+				Attributes: map[string]string{
+					"id": "someid",
+				},
+				Tainted: true,
+			},
+
+			Config: map[string]interface{}{},
+
+			CustomizeDiff: func(d *ResourceDiff, meta interface{}) error {
+				return errors.New("diff customization should not have run")
+			},
+
+			Diff: &terraform.InstanceDiff{
+				Attributes:     map[string]*terraform.ResourceAttrDiff{},
+				DestroyTainted: true,
+			},
+
+			Err: false,
+		},
+
+		{
+			Name: "NewComputed based on a conditional with CustomizeDiffFunc",
+			Schema: map[string]*Schema{
+				"etag": &Schema{
+					Type:     TypeString,
+					Optional: true,
+					Computed: true,
+				},
+				"version_id": &Schema{
+					Type:     TypeString,
+					Computed: true,
+				},
+			},
+
+			State: &terraform.InstanceState{
+				Attributes: map[string]string{
+					"etag":       "foo",
+					"version_id": "1",
+				},
+			},
+
+			Config: map[string]interface{}{
+				"etag": "bar",
+			},
+
+			CustomizeDiff: func(d *ResourceDiff, meta interface{}) error {
+				if d.HasChange("etag") {
+					d.SetNewComputed("version_id")
+				}
+				return nil
+			},
+
+			Diff: &terraform.InstanceDiff{
+				Attributes: map[string]*terraform.ResourceAttrDiff{
+					"etag": &terraform.ResourceAttrDiff{
+						Old: "foo",
+						New: "bar",
+					},
+					"version_id": &terraform.ResourceAttrDiff{
+						Old:         "1",
+						New:         "",
+						NewComputed: true,
+					},
+				},
+			},
+
+			Err: false,
+		},
+
+		{
+			Name: "vetoing a diff",
+			Schema: map[string]*Schema{
+				"foo": &Schema{
+					Type:     TypeString,
+					Optional: true,
+					Computed: true,
+				},
+			},
+
+			State: &terraform.InstanceState{
+				Attributes: map[string]string{
+					"foo": "bar",
+				},
+			},
+
+			Config: map[string]interface{}{
+				"foo": "baz",
+			},
+
+			CustomizeDiff: func(d *ResourceDiff, meta interface{}) error {
+				return fmt.Errorf("diff vetoed")
+			},
+
+			Err: true,
+		},
 	}
 
 	for i, tc := range cases {