provider/aws: Allow WAF SizeConstraint with no tuples

builtin/providers/aws/resource_aws_waf_size_constraint_set.go

@@ -115,6 +115,7 @@ func resourceAwsWafSizeConstraintSetRead(d *schema.ResourceData, meta interface{
 func resourceAwsWafSizeConstraintSetUpdate(d *schema.ResourceData, meta interface{}) error {
 	conn := meta.(*AWSClient).wafconn
 
+	if d.HasChange("size_constraints") {
 		o, n := d.GetChange("size_constraints")
 		oldS, newS := o.(*schema.Set).List(), n.(*schema.Set).List()
 
@@ -122,6 +123,7 @@ func resourceAwsWafSizeConstraintSetUpdate(d *schema.ResourceData, meta interfac
 		if err != nil {
 			return errwrap.Wrapf("[ERROR] Error updating SizeConstraintSet: {{err}}", err)
 		}
+	}
 
 	return resourceAwsWafSizeConstraintSetRead(d, meta)
 }

builtin/providers/aws/resource_aws_waf_size_constraint_set_test.go

@@ -161,6 +161,29 @@ func TestAccAWSWafSizeConstraintSet_changeConstraints(t *testing.T) {
 	})
 }
 
+func TestAccAWSWafSizeConstraintSet_noConstraints(t *testing.T) {
+	var ipset waf.SizeConstraintSet
+	setName := fmt.Sprintf("sizeConstraintSet-%s", acctest.RandString(5))
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckAWSWafSizeConstraintSetDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccAWSWafSizeConstraintSetConfig_noConstraints(setName),
+				Check: resource.ComposeAggregateTestCheckFunc(
+					testAccCheckAWSWafSizeConstraintSetExists("aws_waf_size_constraint_set.size_constraint_set", &ipset),
+					resource.TestCheckResourceAttr(
+						"aws_waf_size_constraint_set.size_constraint_set", "name", setName),
+					resource.TestCheckResourceAttr(
+						"aws_waf_size_constraint_set.size_constraint_set", "size_constraints.#", "0"),
+				),
+			},
+		},
+	})
+}
+
 func testAccCheckAWSWafSizeConstraintSetDisappears(v *waf.SizeConstraintSet) resource.TestCheckFunc {
 	return func(s *terraform.State) error {
 		conn := testAccProvider.Meta().(*AWSClient).wafconn
@@ -308,3 +331,10 @@ resource "aws_waf_size_constraint_set" "size_constraint_set" {
   }
 }`, name)
 }
+
+func testAccAWSWafSizeConstraintSetConfig_noConstraints(name string) string {
+	return fmt.Sprintf(`
+resource "aws_waf_size_constraint_set" "size_constraint_set" {
+  name = "%s"
+}`, name)
+}