From 7d32c8946a9dd9c7b6d6eaa8672f52b976ef35bb Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Tue, 17 Feb 2015 16:55:39 -0800
Subject: [PATCH 1/2] helper/schema: GetOk now only returns true if set to
 non-zero value

---
 helper/schema/resource_data.go      | 12 ++++++++++++
 helper/schema/resource_data_test.go |  2 +-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/helper/schema/resource_data.go b/helper/schema/resource_data.go
index ceffd46b1..615038d2d 100644
--- a/helper/schema/resource_data.go
+++ b/helper/schema/resource_data.go
@@ -77,6 +77,18 @@ func (d *ResourceData) GetChange(key string) (interface{}, interface{}) {
 func (d *ResourceData) GetOk(key string) (interface{}, bool) {
 	r := d.getRaw(key, getSourceSet)
 	exists := r.Exists && !r.Computed
+	if exists {
+		// If it exists, we also want to verify it is not the zero-value.
+		value := r.Value
+		zero := r.Schema.Type.Zero()
+
+		if eq, ok := value.(Equal); ok {
+			exists = !eq.Equal(zero)
+		} else {
+			exists = !reflect.DeepEqual(value, zero)
+		}
+	}
+
 	return r.Value, exists
 }
 
diff --git a/helper/schema/resource_data_test.go b/helper/schema/resource_data_test.go
index 1f484ff4f..091bf5359 100644
--- a/helper/schema/resource_data_test.go
+++ b/helper/schema/resource_data_test.go
@@ -828,7 +828,7 @@ func TestResourceDataGetOk(t *testing.T) {
 
 			Key:   "availability_zone",
 			Value: "",
-			Ok:    true,
+			Ok:    false,
 		},
 
 		{

From fa7f496bef9da0b49728b969ac1b597b73d92c83 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Tue, 17 Feb 2015 16:58:47 -0800
Subject: [PATCH 2/2] helper/schema: zero value of a set should be empty

---
 helper/schema/resource_data_test.go | 26 ++++++++++++++++++++++++++
 helper/schema/schema.go             | 26 ++++++++++++++++++++++++++
 helper/schema/schema_test.go        |  2 +-
 helper/schema/valuetype.go          | 29 ++---------------------------
 4 files changed, 55 insertions(+), 28 deletions(-)

diff --git a/helper/schema/resource_data_test.go b/helper/schema/resource_data_test.go
index 091bf5359..9e35680da 100644
--- a/helper/schema/resource_data_test.go
+++ b/helper/schema/resource_data_test.go
@@ -961,6 +961,32 @@ func TestResourceDataGetOk(t *testing.T) {
 			Value: 0,
 			Ok:    false,
 		},
+
+		{
+			Schema: map[string]*Schema{
+				"ports": &Schema{
+					Type:     TypeSet,
+					Optional: true,
+					Elem:     &Schema{Type: TypeInt},
+					Set:      func(a interface{}) int { return a.(int) },
+				},
+			},
+
+			State: nil,
+
+			Diff: &terraform.InstanceDiff{
+				Attributes: map[string]*terraform.ResourceAttrDiff{
+					"ports.#": &terraform.ResourceAttrDiff{
+						Old: "0",
+						New: "0",
+					},
+				},
+			},
+
+			Key:   "ports",
+			Value: []interface{}{},
+			Ok:    false,
+		},
 	}
 
 	for i, tc := range cases {
diff --git a/helper/schema/schema.go b/helper/schema/schema.go
index 878901418..ff989069c 100644
--- a/helper/schema/schema.go
+++ b/helper/schema/schema.go
@@ -1084,3 +1084,29 @@ func (m schemaMap) validateType(
 		return m.validatePrimitive(k, raw, schema, c)
 	}
 }
+
+// Zero returns the zero value for a type.
+func (t ValueType) Zero() interface{} {
+	switch t {
+	case TypeInvalid:
+		return nil
+	case TypeBool:
+		return false
+	case TypeInt:
+		return 0
+	case TypeFloat:
+		return 0.0
+	case TypeString:
+		return ""
+	case TypeList:
+		return []interface{}{}
+	case TypeMap:
+		return map[string]interface{}{}
+	case TypeSet:
+		return new(Set)
+	case typeObject:
+		return map[string]interface{}{}
+	default:
+		panic(fmt.Sprintf("unknown type %s", t))
+	}
+}
diff --git a/helper/schema/schema_test.go b/helper/schema/schema_test.go
index 8d47d6af9..2f33a3ec2 100644
--- a/helper/schema/schema_test.go
+++ b/helper/schema/schema_test.go
@@ -111,7 +111,7 @@ func TestValueType_Zero(t *testing.T) {
 		{TypeString, ""},
 		{TypeList, []interface{}{}},
 		{TypeMap, map[string]interface{}{}},
-		{TypeSet, nil},
+		{TypeSet, new(Set)},
 	}
 
 	for i, tc := range cases {
diff --git a/helper/schema/valuetype.go b/helper/schema/valuetype.go
index b7b7ac810..9286987d5 100644
--- a/helper/schema/valuetype.go
+++ b/helper/schema/valuetype.go
@@ -2,8 +2,6 @@ package schema
 
 //go:generate stringer -type=ValueType valuetype.go
 
-import "fmt"
-
 // ValueType is an enum of the type that can be represented by a schema.
 type ValueType int
 
@@ -19,28 +17,5 @@ const (
 	typeObject
 )
 
-// Zero returns the zero value for a type.
-func (t ValueType) Zero() interface{} {
-	switch t {
-	case TypeInvalid:
-		return nil
-	case TypeBool:
-		return false
-	case TypeInt:
-		return 0
-	case TypeFloat:
-		return 0.0
-	case TypeString:
-		return ""
-	case TypeList:
-		return []interface{}{}
-	case TypeMap:
-		return map[string]interface{}{}
-	case TypeSet:
-		return nil
-	case typeObject:
-		return map[string]interface{}{}
-	default:
-		panic(fmt.Sprintf("unknown type %s", t))
-	}
-}
+// NOTE: ValueType has more functions defined on it in schema.go. We can't
+// put them here because we reference other files.