Merge pull request #1824 from hashicorp/b-write-count-for-empty-maps

helper/schema: write "attr.#": "0" for empty maps

helper/schema/field_writer_map.go

@@ -141,25 +141,23 @@ func (w *MapFieldWriter) setMap(
 	v := reflect.ValueOf(value)
 	vs := make(map[string]interface{})
 
-	if value != nil {
-		if v.Kind() != reflect.Map {
-			return fmt.Errorf("%s: must be a map", k)
-		}
-		if v.Type().Key().Kind() != reflect.String {
-			return fmt.Errorf("%s: keys must strings", k)
-		}
-		for _, mk := range v.MapKeys() {
-			mv := v.MapIndex(mk)
-			vs[mk.String()] = mv.Interface()
-		}
-	}
-
-	if len(vs) == 0 {
+	if value == nil {
 		// The empty string here means the map is removed.
 		w.result[k] = ""
 		return nil
 	}
 
+	if v.Kind() != reflect.Map {
+		return fmt.Errorf("%s: must be a map", k)
+	}
+	if v.Type().Key().Kind() != reflect.String {
+		return fmt.Errorf("%s: keys must strings", k)
+	}
+	for _, mk := range v.MapKeys() {
+		mv := v.MapIndex(mk)
+		vs[mk.String()] = mv.Interface()
+	}
+
 	// Remove the pure key since we're setting the full map value
 	delete(w.result, k)
 

helper/schema/resource_data_test.go

@@ -2539,7 +2539,9 @@ func TestResourceDataState(t *testing.T) {
 			},
 
 			Result: &terraform.InstanceState{
-				Attributes: map[string]string{},
+				Attributes: map[string]string{
+					"tags.#": "0",
+				},
 			},
 		},