Merge pull request #160 from hashicorp/b-json-empty-list

json/parser: empty list value should not flatten

decoder_test.go

@@ -274,6 +274,14 @@ func TestDecode_interface(t *testing.T) {
 			},
 		},
 
+		{
+			"structure_list_empty.json",
+			false,
+			map[string]interface{}{
+				"foo": []interface{}{},
+			},
+		},
+
 		{
 			"nested_block_comment.hcl",
 			false,

json/parser/flatten.go

@@ -48,6 +48,12 @@ func flattenListType(
 	item *ast.ObjectItem,
 	items []*ast.ObjectItem,
 	frontier []*ast.ObjectItem) ([]*ast.ObjectItem, []*ast.ObjectItem) {
+	// If the list is empty, keep the original list
+	if len(ot.List) == 0 {
+		items = append(items, item)
+		return items, frontier
+	}
+
 	// All the elements of this object must also be objects!
 	for _, subitem := range ot.List {
 		if _, ok := subitem.(*ast.ObjectType); !ok {

json/parser/parser.go

@@ -86,6 +86,7 @@ func (p *Parser) objectList() (*ast.ObjectList, error) {
 			break
 		}
 	}
+
 	return node, nil
 }
 

json/parser/parser_test.go

@@ -186,13 +186,13 @@ func TestFlattenObjects(t *testing.T) {
 	}{
 		{
 			`{
-				"foo": [
-					{
-						"foo": "svh",
-						"bar": "fatih"
-					}
-				]
-			}`,
+					"foo": [
+						{
+							"foo": "svh",
+							"bar": "fatih"
+						}
+					]
+				}`,
 			[]ast.Node{
 				&ast.ObjectType{},
 				&ast.LiteralType{},
@@ -202,15 +202,33 @@ func TestFlattenObjects(t *testing.T) {
 		},
 		{
 			`{
-				"variable": {
-					"foo": {}
-				}
-			}`,
+					"variable": {
+						"foo": {}
+					}
+				}`,
 			[]ast.Node{
 				&ast.ObjectType{},
 			},
 			1,
 		},
+		{
+			`{
+				"empty": []
+			}`,
+			[]ast.Node{
+				&ast.ListType{},
+			},
+			1,
+		},
+		{
+			`{
+				"basic": [1, 2, 3]
+			}`,
+			[]ast.Node{
+				&ast.ListType{},
+			},
+			1,
+		},
 	}
 
 	for _, l := range literals {
@@ -360,7 +378,7 @@ func TestParse_inline(t *testing.T) {
 func equals(tb testing.TB, exp, act interface{}) {
 	if !reflect.DeepEqual(exp, act) {
 		_, file, line, _ := runtime.Caller(1)
-		fmt.Printf("\033[31m%s:%d:\n\n\texp: %#v\n\n\tgot: %#v\033[39m\n\n", filepath.Base(file), line, exp, act)
+		fmt.Printf("\033[31m%s:%d:\n\n\texp: %s\n\n\tgot: %s\033[39m\n\n", filepath.Base(file), line, exp, act)
 		tb.FailNow()
 	}
 }

test-fixtures/structure_list_empty.json

@@ -0,0 +1,3 @@
+{
+	"foo": []
+}