internal/core/adt: prevent nil interface bug for Source
Fixes #521
Change-Id: I59c789f72ba9c6597378279f26458d77721a4da1
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/7122
Reviewed-by: Paul Jolly <paul@myitcv.org.uk>
Reviewed-by: CUE cueckoo <cueckoo@gmail.com>
diff --git a/internal/core/adt/expr_test.go b/internal/core/adt/expr_test.go
new file mode 100644
index 0000000..3d7a936
--- /dev/null
+++ b/internal/core/adt/expr_test.go
@@ -0,0 +1,74 @@
+// Copyright 2020 CUE Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package adt
+
+import (
+ "fmt"
+ "testing"
+)
+
+func TestNilSource(t *testing.T) {
+ testCases := []Node{
+ &BasicType{},
+ &BinaryExpr{},
+ &Bool{},
+ &Bottom{},
+ &BoundExpr{},
+ &BoundValue{},
+ &Builtin{},
+ &BuiltinValidator{},
+ &BulkOptionalField{},
+ &Bytes{},
+ &CallExpr{},
+ &Conjunction{},
+ &Disjunction{},
+ &DisjunctionExpr{},
+ &DynamicField{},
+ &DynamicReference{},
+ &Ellipsis{},
+ &Field{},
+ &FieldReference{},
+ &ForClause{},
+ &IfClause{},
+ &ImportReference{},
+ &IndexExpr{},
+ &Interpolation{},
+ &LabelReference{},
+ &LetClause{},
+ &LetReference{},
+ &ListLit{},
+ &ListMarker{},
+ &NodeLink{},
+ &Null{},
+ &Num{},
+ &OptionalField{},
+ &SelectorExpr{},
+ &SliceExpr{},
+ &String{},
+ &StructLit{},
+ &StructMarker{},
+ &Top{},
+ &UnaryExpr{},
+ &ValueClause{},
+ &Vertex{},
+ }
+ for _, x := range testCases {
+ t.Run(fmt.Sprintf("%T", x), func(t *testing.T) {
+ if x.Source() != nil {
+ t.Error("nil source did not return nil")
+ }
+ })
+ }
+}
