helper/diff: mark removed keys as removed

helper/diff/diff_test.go

@@ -58,6 +58,9 @@ func testResourceDiffStr(rd *terraform.ResourceDiff) string {
 		if attrDiff.NewComputed {
 			v = "<computed>"
 		}
+		if attrDiff.NewRemoved {
+			v = "<removed>"
+		}
 
 		newResource := ""
 		if attrDiff.RequiresNew {

helper/diff/resource_builder.go

@@ -116,7 +116,7 @@ func (b *ResourceBuilder) Diff(
 		for k, _ := range matchingKeys {
 			attrs[k] = &terraform.ResourceAttrDiff{
 				Old:        s.Attributes[k],
-				New:  "",
+				NewRemoved: true,
 				Type:       terraform.DiffAttrInput,
 			}
 		}

helper/diff/resource_builder_test.go

@@ -240,7 +240,7 @@ const testRBComplexDiff = `UPDATE
 `
 
 const testRBComplexReplaceDiff = `UPDATE
-  IN  listener.0.port:  "80" => ""
+  IN  listener.0.port:  "80" => "<removed>"
   IN  listener.0.value: "" => "50"
 `
 

terraform/diff.go

@@ -165,6 +165,7 @@ type ResourceAttrDiff struct {
 	Old         string      // Old Value
 	New         string      // New Value
 	NewComputed bool        // True if new value is computed (unknown currently)
+	NewRemoved  bool        // True if this attribute is being removed
 	NewExtra    interface{} // Extra information for the provider
 	RequiresNew bool        // True if change requires new resource
 	Type        DiffAttrType