Implement UniqueArgumentNames validator

validator/known_argument_names.go

@@ -6,7 +6,7 @@ import (
 
 func init() {
 	fieldVisitors = append(fieldVisitors, knownFieldArgumentNames)
-	directiveVisitors = append(directiveVisitors, knowDirectiveArgumentNames)
+	directiveVisitors = append(directiveVisitors, knownDirectiveArgumentNames)
 }
 
 // A GraphQL field is only valid if all supplied arguments are defined by that field.
@@ -33,7 +33,7 @@ func knownFieldArgumentNames(ctx *vctx, parentDef *gqlparser.Definition, fieldDe
 	}
 }
 
-func knowDirectiveArgumentNames(ctx *vctx, parentDef *gqlparser.Definition, directiveDef *gqlparser.DirectiveDefinition, directive *gqlparser.Directive, location gqlparser.DirectiveLocation) {
+func knownDirectiveArgumentNames(ctx *vctx, parentDef *gqlparser.Definition, directiveDef *gqlparser.DirectiveDefinition, directive *gqlparser.Directive, location gqlparser.DirectiveLocation) {
 	if directiveDef == nil {
 		return
 	}

validator/unique_argument_names.go

@@ -0,0 +1,34 @@
+package validator
+
+import (
+	"github.com/vektah/gqlparser"
+)
+
+func init() {
+	fieldVisitors = append(fieldVisitors, uniqueFieldArgumentNames)
+	directiveVisitors = append(directiveVisitors, uniqueDirectiveArgumentNames)
+}
+
+func checkUniqueArgs(ctx *vctx, args []gqlparser.Argument) {
+	knownArgNames := map[string]bool{}
+
+	for _, arg := range args {
+		if knownArgNames[arg.Name] {
+			ctx.errors = append(ctx.errors, Error(
+				Rule("UniqueArgumentNames"),
+				Message(`There can be only one argument named "%s".`, arg.Name),
+			))
+		}
+
+		knownArgNames[arg.Name] = true
+	}
+}
+
+// A GraphQL field is only valid if all supplied arguments are defined by that field.
+func uniqueFieldArgumentNames(ctx *vctx, parentDef *gqlparser.Definition, fieldDef *gqlparser.FieldDefinition, field *gqlparser.Field) {
+	checkUniqueArgs(ctx, field.Arguments)
+}
+
+func uniqueDirectiveArgumentNames(ctx *vctx, parentDef *gqlparser.Definition, directiveDef *gqlparser.DirectiveDefinition, directive *gqlparser.Directive, location gqlparser.DirectiveLocation) {
+	checkUniqueArgs(ctx, directive.Arguments)
+}

validator/validate_test.go

@@ -43,6 +43,7 @@ func TestSpec(t *testing.T) {
 
 	t.Run("ScalarLeafs", runSpec(schemas, deviations, "../spec/validation/ScalarLeafs.yml"))
 	t.Run("SingleFieldSubscriptions", runSpec(schemas, deviations, "../spec/validation/SingleFieldSubscriptions.yml"))
+	t.Run("UniqueArgumentNames", runSpec(schemas, deviations, "../spec/validation/UniqueArgumentNames.yml"))
 }
 
 func runSpec(schemas []*gqlparser.Schema, deviations map[string]*Spec, filename string) func(t *testing.T) {