address review

pkg/tfbridge/property_path.go

@@ -83,13 +83,23 @@ func (SkipChildrenError) Error() string {
 	return "skip children"
 }
 
+type TypeMismatchError struct{}
+
+func (TypeMismatchError) Error() string {
+	return "type mismatch"
+}
+
 type twoPropertyValueVisitor func(path propertyPath, val1, val2 resource.PropertyValue) error
 
 // walkTwoPropertyValues walks the two property values and calls the visitor for each step.
 // It returns an error if the visitor returns an error other than SkipChildrenError.
 //
 // The visitor can return SkipChildrenError to skip the children of the current step.
 // In case the two values have different types, we walk both values, starting with val1.
+//
+// Note that elements inside a Secret or Output value will not get visited.
+//
+// Can return a TypeMismatchError in case the two values' types do not match.
 func walkTwoPropertyValues(
 	path propertyPath,
 	val1, val2 resource.PropertyValue,
@@ -103,6 +113,10 @@ func walkTwoPropertyValues(
 		return err
 	}
 
+	if val1.IsNull() || val2.IsNull() {
+		return nil
+	}
+
 	if val1.IsArray() && val2.IsArray() {
 		arr1 := val1.ArrayValue()
 		arr2 := val2.ArrayValue()
@@ -134,44 +148,8 @@ func walkTwoPropertyValues(
 				return err
 			}
 		}
-	} else {
-		if val1.IsArray() {
-			arr1 := val1.ArrayValue()
-			for i, v := range arr1 {
-				childPath := path.Index(i)
-				err := walkTwoPropertyValues(childPath, v, resource.NewNullProperty(), visitor)
-				if err != nil {
-					return err
-				}
-			}
-		} else if val1.IsObject() {
-			obj1 := val1.ObjectValue()
-			for k, v := range obj1 {
-				err := walkTwoPropertyValues(path.Subkey(k), v, resource.NewNullProperty(), visitor)
-				if err != nil {
-					return err
-				}
-			}
-		}
-
-		if val2.IsArray() {
-			arr2 := val2.ArrayValue()
-			for i, v := range arr2 {
-				childPath := path.Index(i)
-				err := walkTwoPropertyValues(childPath, resource.NewNullProperty(), v, visitor)
-				if err != nil {
-					return err
-				}
-			}
-		} else if val2.IsObject() {
-			obj2 := val2.ObjectValue()
-			for k, v := range obj2 {
-				err := walkTwoPropertyValues(path.Subkey(k), resource.NewNullProperty(), v, visitor)
-				if err != nil {
-					return err
-				}
-			}
-		}
+	} else if val1.IsArray() || val2.IsArray() || val1.IsObject() || val2.IsObject() {
+		return TypeMismatchError{}
 	}
 	return nil
 }

pkg/tfbridge/property_path_test.go

@@ -157,8 +157,8 @@ func TestWalkTwoPropertyValues(t *testing.T) {
 				return nil
 			})
 
-		require.NoError(t, err)
-		require.Equal(t, []string{"", "a", "a[0]", "a.b"}, visited)
+		require.Error(t, err)
+		require.IsType(t, TypeMismatchError{}, err)
 	})
 
 	t.Run("both arrays error", func(t *testing.T) {
@@ -228,6 +228,7 @@ func TestWalkTwoPropertyValues(t *testing.T) {
 			})
 
 		require.Error(t, err)
+		require.IsType(t, TypeMismatchError{}, err)
 	})
 
 	t.Run("mismatched types first object error", func(t *testing.T) {
@@ -251,6 +252,7 @@ func TestWalkTwoPropertyValues(t *testing.T) {
 			})
 
 		require.Error(t, err)
+		require.IsType(t, TypeMismatchError{}, err)
 	})
 
 	t.Run("mismatched types second array error", func(t *testing.T) {
@@ -274,6 +276,7 @@ func TestWalkTwoPropertyValues(t *testing.T) {
 			})
 
 		require.Error(t, err)
+		require.IsType(t, TypeMismatchError{}, err)
 	})
 
 	t.Run("mismatched types second object error", func(t *testing.T) {
@@ -297,5 +300,6 @@ func TestWalkTwoPropertyValues(t *testing.T) {
 			})
 
 		require.Error(t, err)
+		require.IsType(t, TypeMismatchError{}, err)
 	})
 }