make semantic equality symmetrical

apstra/custom_types/string_with_alt_values_value.go

@@ -31,6 +31,9 @@ func (v StringWithAltValues) Equal(o attr.Value) bool {
 	return v.StringValue.Equal(other.StringValue)
 }
 
+// StringSemanticEquals implements the semantic equality check. According to this
+// (https://discuss.hashicorp.com/t/can-semantic-equality-check-in-custom-types-be-asymmetrical/60644/2?u=hqnvylrx)
+// semantic equality checks on custom types are always implementeed as oldValue.SemanticEquals(ctx, newValue)
 func (v StringWithAltValues) StringSemanticEquals(_ context.Context, newValuable basetypes.StringValuable) (bool, diag.Diagnostics) {
 	var diags diag.Diagnostics
 
@@ -59,6 +62,13 @@ func (v StringWithAltValues) StringSemanticEquals(_ context.Context, newValuable
 		}
 	}
 
+	// check old value against new "alt" values
+	for _, a := range newValue.altValues {
+		if a.Equal(v) {
+			return true, diags
+		}
+	}
+
 	return false, diags
 }
 

apstra/custom_types/string_with_alt_values_value_test.go

@@ -26,11 +26,16 @@ func TestStringWithAltValues_StringSemanticEquals(t *testing.T) {
 			givenValue:    customtypes.NewStringWithAltValuesValue("foo"),
 			expectedMatch: true,
 		},
-		"semantically equal": {
+		"semantically equal - given matches an alt value": {
 			currentValue:  customtypes.NewStringWithAltValuesValue("foo", "bar", "baz", "bang"),
 			givenValue:    customtypes.NewStringWithAltValuesValue("baz"),
 			expectedMatch: true,
 		},
+		"semantically equal - current matches an alt value": {
+			currentValue:  customtypes.NewStringWithAltValuesValue("baz"),
+			givenValue:    customtypes.NewStringWithAltValuesValue("foo", "bar", "baz", "bang"),
+			expectedMatch: true,
+		},
 		"not equal": {
 			currentValue:  customtypes.NewStringWithAltValuesValue("foo", "bar", "baz", "bang"),
 			givenValue:    customtypes.NewStringWithAltValuesValue("FOO"),