fix false positive case in no-unreachable-types rule when directive is used on schema (#755)

Author: Dimitri POSTOLOV

.changeset/shiny-buttons-relax.md

@@ -0,0 +1,5 @@
+---
+'@graphql-eslint/eslint-plugin': minor
+---
+
+fix false positive case in `no-unreachable-types` rule when directive on root schema is used

packages/plugin/src/graphql-ast.ts

@@ -1,12 +1,4 @@
-import {
-  ASTNode,
-  ASTVisitor,
-  TypeInfo,
-  GraphQLSchema,
-  visit,
-  isInterfaceType,
-  visitWithTypeInfo,
-} from 'graphql';
+import { ASTNode, ASTVisitor, TypeInfo, GraphQLSchema, visit, isInterfaceType, visitWithTypeInfo } from 'graphql';
 import { SiblingOperations } from './sibling-operations';
 import { getTypeName } from './utils';
 
@@ -50,7 +42,12 @@ export function getReachableTypes(schema: GraphQLSchema): ReachableTypes {
     NamedType: collect,
   };
 
-  for (const type of [schema.getQueryType(), schema.getMutationType(), schema.getSubscriptionType()]) {
+  for (const type of [
+    schema, // visiting SchemaDefinition node
+    schema.getQueryType(),
+    schema.getMutationType(),
+    schema.getSubscriptionType(),
+  ]) {
     if (type) {
       visit(type.astNode, visitor);
     }

packages/plugin/tests/no-unreachable-types.spec.ts

@@ -8,7 +8,9 @@ const useSchema = (schema: string): { code: string; parserOptions: ParserOptions
   };
 };
 
-new GraphQLRuleTester().runGraphQLTests('no-unreachable-types', rule, {
+const ruleTester = new GraphQLRuleTester();
+
+ruleTester.runGraphQLTests('no-unreachable-types', rule, {
   valid: [
     useSchema(/* GraphQL */ `
       scalar A
@@ -118,6 +120,18 @@ new GraphQLRuleTester().runGraphQLTests('no-unreachable-types', rule, {
         me: User
       }
     `),
+    {
+      name: 'directive on schema',
+      ...useSchema(/* GraphQL */ `
+        type Query
+
+        schema @good {
+          query: Query
+        }
+
+        directive @good on SCHEMA
+      `),
+    },
   ],
   invalid: [
     {