From bbe8d040dc30abda3085554b4aea2e89a313f322 Mon Sep 17 00:00:00 2001
From: Steve Coffman <StevenACoffman@users.noreply.github.com>
Date: Fri, 23 Sep 2022 11:19:43 -0400
Subject: [PATCH] Prefer to wrap third party errors (#243)

Signed-off-by: Steve Coffman <steve@khanacademy.org>

Signed-off-by: Steve Coffman <steve@khanacademy.org>
---
 gqlerror/error.go           |  7 +++++++
 gqlparser.go                | 19 +++++++++++++++----
 parser/testrunner/runner.go |  8 ++++++--
 validator/validator.go      | 10 +++++++++-
 4 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/gqlerror/error.go b/gqlerror/error.go
index 8145061a..2620d593 100644
--- a/gqlerror/error.go
+++ b/gqlerror/error.go
@@ -107,6 +107,13 @@ func WrapPath(path ast.Path, err error) *Error {
 	}
 }
 
+func Wrap(err error) *Error {
+	return &Error{
+		err:     err,
+		Message: err.Error(),
+	}
+}
+
 func Errorf(message string, args ...interface{}) *Error {
 	return &Error{
 		Message: fmt.Sprintf(message, args...),
diff --git a/gqlparser.go b/gqlparser.go
index 69a2cf18..3a6e2d13 100644
--- a/gqlparser.go
+++ b/gqlparser.go
@@ -11,7 +11,15 @@ import (
 )
 
 func LoadSchema(str ...*ast.Source) (*ast.Schema, error) {
-	return validator.LoadSchema(append([]*ast.Source{validator.Prelude}, str...)...)
+	ast, err := validator.LoadSchema(append([]*ast.Source{validator.Prelude}, str...)...)
+	gqlErr, ok := err.(*gqlerror.Error)
+	if ok {
+		return ast, gqlErr
+	}
+	if err != nil {
+		return ast, gqlerror.Wrap(err)
+	}
+	return ast, nil
 }
 
 func MustLoadSchema(str ...*ast.Source) *ast.Schema {
@@ -25,11 +33,14 @@ func MustLoadSchema(str ...*ast.Source) *ast.Schema {
 func LoadQuery(schema *ast.Schema, str string) (*ast.QueryDocument, gqlerror.List) {
 	query, err := parser.ParseQuery(&ast.Source{Input: str})
 	if err != nil {
-		gqlErr := err.(*gqlerror.Error)
-		return nil, gqlerror.List{gqlErr}
+		gqlErr, ok := err.(*gqlerror.Error)
+		if ok {
+			return nil, gqlerror.List{gqlErr}
+		}
+		return nil, gqlerror.List{gqlerror.Wrap(err)}
 	}
 	errs := validator.Validate(schema, query)
-	if errs != nil {
+	if len(errs) > 0 {
 		return nil, errs
 	}
 
diff --git a/parser/testrunner/runner.go b/parser/testrunner/runner.go
index 5eea2389..b1f35504 100644
--- a/parser/testrunner/runner.go
+++ b/parser/testrunner/runner.go
@@ -55,8 +55,12 @@ func Test(t *testing.T, filename string, f func(t *testing.T, input string) Spec
 
 					if spec.Error == nil {
 						if result.Error != nil {
-							gqlErr := err.(*gqlerror.Error)
-							t.Errorf("unexpected error %s", gqlErr.Message)
+							gqlErr, ok := err.(*gqlerror.Error)
+							if ok {
+								t.Errorf("unexpected error %s", gqlErr.Message)
+							} else {
+								t.Errorf("unexpected error %+v", gqlerror.Wrap(err))
+							}
 						}
 					} else if result.Error == nil {
 						t.Errorf("expected error but got none")
diff --git a/validator/validator.go b/validator/validator.go
index c5426ada..b4f37ce2 100644
--- a/validator/validator.go
+++ b/validator/validator.go
@@ -25,7 +25,15 @@ func AddRule(name string, f ruleFunc) {
 
 func Validate(schema *Schema, doc *QueryDocument) gqlerror.List {
 	var errs gqlerror.List
-
+	if schema == nil {
+		errs = append(errs, gqlerror.Errorf("cannot validate as Schema is nil"))
+	}
+	if doc == nil {
+		errs = append(errs, gqlerror.Errorf("cannot validate as QueryDocument is nil"))
+	}
+	if len(errs) > 0 {
+		return errs
+	}
 	observers := &Events{}
 	for i := range rules {
 		rule := rules[i]