Fix useless error message 'invalid atom'

Author: jennybuckley

typed/helpers.go

@@ -114,17 +114,27 @@ func resolveSchema(s *schema.Schema, tr schema.TypeRef, v *value.Value, ah atomH
 	return handleAtom(a, tr, ah)
 }
 
-func deduceAtom(a schema.Atom, v *value.Value) schema.Atom {
+// deduceAtom determines which of the possible types in atom 'atom' applies to value 'val'.
+// If val is of a type allowed by atom, return a copy of atom with all other types set to nil.
+// if val is nil, or is not of a type allowed by atom, just return the original atom,
+// and validation will fail at a later stage. (with a more useful error)
+func deduceAtom(atom schema.Atom, val *value.Value) schema.Atom {
 	switch {
-	case v == nil:
-	case v.FloatValue != nil, v.IntValue != nil, v.StringValue != nil, v.BooleanValue != nil:
-		return schema.Atom{Scalar: a.Scalar}
-	case v.ListValue != nil:
-		return schema.Atom{List: a.List}
-	case v.MapValue != nil:
-		return schema.Atom{Map: a.Map}
+	case val == nil:
+	case val.FloatValue != nil, val.IntValue != nil, val.StringValue != nil, val.BooleanValue != nil:
+		if atom.Scalar != nil {
+			return schema.Atom{Scalar: atom.Scalar}
+		}
+	case val.ListValue != nil:
+		if atom.List != nil {
+			return schema.Atom{List: atom.List}
+		}
+	case val.MapValue != nil:
+		if atom.Map != nil {
+			return schema.Atom{Map: atom.Map}
+		}
 	}
-	return a
+	return atom
 }
 
 func handleAtom(a schema.Atom, tr schema.TypeRef, ah atomHandler) ValidationErrors {

typed/validate.go

@@ -198,7 +198,11 @@ func (v *validatingObjectWalker) visitMapItems(t *schema.Map, m *value.Map) (err
 		} else {
 			v2 := v.prepareDescent(pe, t.ElementType)
 			v2.value = item.Value
-			errs = append(errs, v2.validate()...)
+			if (t.ElementType == schema.TypeRef{}) {
+				errs = append(errs, v2.errorf("field not declared in schema")...)
+			} else {
+				errs = append(errs, v2.validate()...)
+			}
 			v2.doNode()
 			v.finishDescent(v2)
 		}

typed/validate_test.go

@@ -18,6 +18,7 @@ package typed_test
 
 import (
 	"fmt"
+	"strings"
 	"testing"
 
 	"sigs.k8s.io/structured-merge-diff/v2/schema"
@@ -216,6 +217,8 @@ var validationCases = []validationTestCase{{
 	invalidObjects: []typed.YAMLObject{
 		`{"key":true,"value":1}`,
 		`{"list":{"key":true,"value":1}}`,
+		`{"list":true}`,
+		`true`,
 		`{"list":[{"key":true,"value":1}]}`,
 		`{"list":[{"key":[],"value":1}]}`,
 		`{"list":[{"key":{},"value":1}]}`,
@@ -261,6 +264,9 @@ func (tt validationTestCase) test(t *testing.T) {
 			if err == nil {
 				t.Errorf("Object should fail: %v\n%v", err, iv)
 			}
+			if strings.Contains(err.Error(), "invalid atom") {
+				t.Errorf("Error should be useful, but got: %v\n%v", err, iv)
+			}
 		})
 	}
 }