add fuzzing for schema.Exec, schema and query parsing

Author: João Veiga

go.mod

@@ -2,4 +2,5 @@ module github.com/graph-gophers/graphql-go
 
 require github.com/opentracing/opentracing-go v1.1.0
 
+
 go 1.13

graphql_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"strings"
 	"sync"
 	"testing"
 	"time"
@@ -4297,3 +4298,28 @@ func TestInterfaceImplementingInterface(t *testing.T) {
 			`,
 	}})
 }
+
+type query struct{}
+
+func (_ *query) Hello() string { return "Hello, world!" }
+func (_ *query) Hi(string, string) string { return "Hello, world!" }
+func (_ *query) LaunchMissil(string, string) string { return "Hello, world!" }
+
+func FuzzSchemaExec(f *testing.F) {
+    f.Fuzz(func(t *testing.T, s string, queryString , operationName string) {
+	    defer func(){
+		    if err := recover(); err != nil{
+			    if !strings.Contains(err.(error).Error(), "invalid syntax"){
+				    panic(err)
+			    }
+		    }
+	    }()
+	    ctx := context.Background()
+	    variables := map[string]interface{}{}
+	    schema,err := graphql.ParseSchema(s, &query{})
+	    if err != nil {
+		    t.Skip()
+	    }
+	    schema.Exec(ctx, queryString, operationName, variables)
+    })
+}

internal/query/query_test.go

@@ -0,0 +1,12 @@
+package query
+
+import (
+	"testing"
+)
+
+func FuzzParseQuery(f *testing.F) {
+    f.Fuzz(func(t *testing.T, queryStr string) {
+        Parse(queryStr)
+    })
+}
+

internal/schema/schema_test.go

@@ -1007,3 +1007,10 @@ func TestInterfaceImplementsInterface(t *testing.T) {
 		})
 	}
 }
+
+func FuzzParse(f *testing.F){
+	f.Fuzz(func(t *testing.T, schemaString string, useStringDescriptions bool){
+		s := schema.New()
+		schema.Parse(s, schemaString, useStringDescriptions)
+	})
+}