From fb3fc1d26dea75086d35271c80a54ce236a77606 Mon Sep 17 00:00:00 2001
From: vvakame <vvakame+dev@gmail.com>
Date: Wed, 11 Jul 2018 14:55:41 +0900
Subject: [PATCH] Implement KnownFragmentNames validator

---
 validator/known_fragment_names.go | 20 ++++++++++++++++++++
 validator/validate_test.go        |  1 +
 validator/walk.go                 |  8 ++++++++
 3 files changed, 29 insertions(+)
 create mode 100644 validator/known_fragment_names.go

diff --git a/validator/known_fragment_names.go b/validator/known_fragment_names.go
new file mode 100644
index 00000000..39e2bbfb
--- /dev/null
+++ b/validator/known_fragment_names.go
@@ -0,0 +1,20 @@
+package validator
+
+import (
+	"fmt"
+
+	"github.com/vektah/gqlparser"
+)
+
+func init() {
+	addRule("KnownFragmentNames", func(observers *Events, addError addErrFunc) {
+		observers.OnFragmentSpread(func(walker *Walker, parentDef *gqlparser.Definition, fragmentDef *gqlparser.FragmentDefinition, fragmentSpread *gqlparser.FragmentSpread) {
+			if fragmentDef != nil {
+				return
+			}
+
+			message := fmt.Sprintf(`Unknown fragment "%s".`, fragmentSpread.Name)
+			addError(Message(message))
+		})
+	})
+}
diff --git a/validator/validate_test.go b/validator/validate_test.go
index c9b2d4a6..58ab783c 100644
--- a/validator/validate_test.go
+++ b/validator/validate_test.go
@@ -40,6 +40,7 @@ func TestSpec(t *testing.T) {
 	t.Run("FragmentsOnCompositeTypes", runSpec(schemas, deviations, "../spec/validation/FragmentsOnCompositeTypes.yml"))
 	t.Run("KnownArgumentNames", runSpec(schemas, deviations, "../spec/validation/KnownArgumentNames.yml"))
 	t.Run("KnownDirectives", runSpec(schemas, deviations, "../spec/validation/KnownDirectives.yml"))
+	t.Run("KnownFragmentNames", runSpec(schemas, deviations, "../spec/validation/KnownFragmentNames.yml"))
 
 	t.Run("LoneAnonymousOperation", runSpec(schemas, deviations, "../spec/validation/LoneAnonymousOperation.yml"))
 
diff --git a/validator/walk.go b/validator/walk.go
index 34b1537e..18827099 100644
--- a/validator/walk.go
+++ b/validator/walk.go
@@ -14,6 +14,7 @@ type Events struct {
 	field            []func(walker *Walker, parentDef *gqlparser.Definition, fieldDef *gqlparser.FieldDefinition, field *gqlparser.Field)
 	fragment         []func(walker *Walker, parentDef *gqlparser.Definition, fragment *gqlparser.FragmentDefinition)
 	inlineFragment   []func(walker *Walker, parentDef *gqlparser.Definition, inlineFragment *gqlparser.InlineFragment)
+	fragmentSpread   []func(walker *Walker, parentDef *gqlparser.Definition, fragmentDef *gqlparser.FragmentDefinition, fragmentSpread *gqlparser.FragmentSpread)
 	directive        []func(walker *Walker, parentDef *gqlparser.Definition, directiveDef *gqlparser.DirectiveDefinition, directive *gqlparser.Directive, location gqlparser.DirectiveLocation)
 	directiveList    []func(walker *Walker, parentDef *gqlparser.Definition, directives []gqlparser.Directive, location gqlparser.DirectiveLocation)
 	value            []func(walker *Walker, value gqlparser.Value)
@@ -31,6 +32,9 @@ func (o *Events) OnFragment(f func(walker *Walker, parentDef *gqlparser.Definiti
 func (o *Events) OnInlineFragment(f func(walker *Walker, parentDef *gqlparser.Definition, inlineFragment *gqlparser.InlineFragment)) {
 	o.inlineFragment = append(o.inlineFragment, f)
 }
+func (o *Events) OnFragmentSpread(f func(walker *Walker, parentDef *gqlparser.Definition, fragmentDef *gqlparser.FragmentDefinition, fragmentSpread *gqlparser.FragmentSpread)) {
+	o.fragmentSpread = append(o.fragmentSpread, f)
+}
 func (o *Events) OnDirective(f func(walker *Walker, parentDef *gqlparser.Definition, directiveDef *gqlparser.DirectiveDefinition, directive *gqlparser.Directive, location gqlparser.DirectiveLocation)) {
 	o.directive = append(o.directive, f)
 }
@@ -189,6 +193,10 @@ func (w *Walker) walkSelection(parentDef *gqlparser.Definition, it gqlparser.Sel
 	case gqlparser.FragmentSpread:
 		def := w.Document.GetFragment(it.Name)
 
+		for _, v := range w.Observers.fragmentSpread {
+			v(w, parentDef, def, &it)
+		}
+
 		var nextParentDef *gqlparser.Definition
 		if def != nil {
 			nextParentDef = w.Schema.Types[def.TypeCondition.Name()]