Implement UniqueFragmentNames validator

Author: Adam Scarr

validator/unique_fragment_names.go

@@ -0,0 +1,20 @@
+package validator
+
+import (
+	"github.com/vektah/gqlparser"
+)
+
+func init() {
+	fragmentVisitors = append(fragmentVisitors, uniqueFragmentNames)
+}
+
+// A GraphQL document is only valid if all defined fragments have unique names.
+func uniqueFragmentNames(ctx *vctx, parentDef *gqlparser.Definition, fragment *gqlparser.FragmentDefinition) {
+	if ctx.seenFragments[fragment.Name] {
+		ctx.errors = append(ctx.errors, Error(
+			Rule("UniqueFragmentNames"),
+			Message(`There can be only one fragment named "%s".`, fragment.Name),
+		))
+	}
+	ctx.seenFragments[fragment.Name] = true
+}

validator/validate.go

@@ -7,8 +7,9 @@ import (
 
 func Validate(schema *Schema, doc *QueryDocument) []errors.Validation {
 	ctx := vctx{
-		schema:   schema,
-		document: doc,
+		schema:        schema,
+		document:      doc,
+		seenFragments: map[string]bool{},
 	}
 
 	ctx.walk()

validator/validate_test.go

@@ -45,6 +45,7 @@ func TestSpec(t *testing.T) {
 	t.Run("SingleFieldSubscriptions", runSpec(schemas, deviations, "../spec/validation/SingleFieldSubscriptions.yml"))
 	t.Run("UniqueArgumentNames", runSpec(schemas, deviations, "../spec/validation/UniqueArgumentNames.yml"))
 	t.Run("UniqueDirectivesPerLocation", runSpec(schemas, deviations, "../spec/validation/UniqueDirectivesPerLocation.yml"))
+	t.Run("UniqueFragmentNames", runSpec(schemas, deviations, "../spec/validation/UniqueFragmentNames.yml"))
 }
 
 func runSpec(schemas []*gqlparser.Schema, deviations map[string]*Spec, filename string) func(t *testing.T) {

validator/walk.go

@@ -7,12 +7,12 @@ import (
 	"github.com/vektah/gqlparser/errors"
 )
 
-var operationVisitor []func(vctx *vctx, operation *gqlparser.OperationDefinition)
-var fieldVisitors []func(vctx *vctx, parentDef *gqlparser.Definition, fieldDef *gqlparser.FieldDefinition, field *gqlparser.Field)
-var fragmentVisitors []func(vctx *vctx, parentDef *gqlparser.Definition, fragment *gqlparser.FragmentDefinition)
-var inlineFragmentVisitors []func(vctx *vctx, parentDef *gqlparser.Definition, inlineFragment *gqlparser.InlineFragment)
-var directiveVisitors []func(vctx *vctx, parentDef *gqlparser.Definition, directiveDef *gqlparser.DirectiveDefinition, directive *gqlparser.Directive, location gqlparser.DirectiveLocation)
-var directiveListVisitors []func(vctx *vctx, parentDef *gqlparser.Definition, directives []gqlparser.Directive, location gqlparser.DirectiveLocation)
+var operationVisitor []func(ctx *vctx, operation *gqlparser.OperationDefinition)
+var fieldVisitors []func(ctx *vctx, parentDef *gqlparser.Definition, fieldDef *gqlparser.FieldDefinition, field *gqlparser.Field)
+var fragmentVisitors []func(ctx *vctx, parentDef *gqlparser.Definition, fragment *gqlparser.FragmentDefinition)
+var inlineFragmentVisitors []func(ctx *vctx, parentDef *gqlparser.Definition, inlineFragment *gqlparser.InlineFragment)
+var directiveVisitors []func(ctx *vctx, parentDef *gqlparser.Definition, directiveDef *gqlparser.DirectiveDefinition, directive *gqlparser.Directive, location gqlparser.DirectiveLocation)
+var directiveListVisitors []func(ctx *vctx, parentDef *gqlparser.Definition, directives []gqlparser.Directive, location gqlparser.DirectiveLocation)
 
 func init() {
 	//fieldVisitors = append(fieldVisitors, func(vctx *vctx, parentDef *gqlparser.Definition, fieldDef *gqlparser.FieldDefinition, field *gqlparser.Field) {
@@ -24,6 +24,9 @@ type vctx struct {
 	schema   *gqlparser.Schema
 	document *gqlparser.QueryDocument
 	errors   []errors.Validation
+
+	// todo: Move this somewhere better
+	seenFragments map[string]bool
 }
 
 func (c *vctx) walk() {