add fuzzing for schema.Exec, schema and query parsing

go.mod

@@ -1,5 +1,8 @@
 module github.com/graph-gophers/graphql-go
 
-require github.com/opentracing/opentracing-go v1.1.0
+require (
+	github.com/opentracing/opentracing-go v1.1.0
+	github.com/stretchr/testify v1.3.0 // indirect
+)
 
 go 1.13

go.sum

@@ -1,2 +1,9 @@
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/opentracing/opentracing-go v1.1.0 h1:pWlfV3Bxv7k65HYwkikxat0+s3pV4bsqf19k25Ur8rU=
 github.com/opentracing/opentracing-go v1.1.0/go.mod h1:UkNAQd3GIcIGf0SeVgPpRdFStlNbqXla1AfSYxPUl2o=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=

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)
+	})
+}