fix: validation caching schema check (#2720)

.changeset/proud-oranges-warn.md

@@ -0,0 +1,5 @@
+---
+'graphql-yoga': patch
+---
+
+Skip validation caching when there is no `schema` specified. This previously caused a cryptic error message when reaching execution/validation without a schema. Now the missing schema error will actually originate from within the `validate` function instead.

packages/graphql-yoga/__tests__/schema.spec.ts

@@ -7,6 +7,10 @@ describe('schema', () => {
   it('missing schema causes a error', async () => {
     const yoga = createYoga({
       logging: false,
+      maskedErrors: {
+        /** We use dev mode in order to verify that our error message is originating from within graphql-js and not our code. */
+        isDev: true,
+      },
     })
 
     const response = await yoga.fetch('http://yoga/graphql', {
@@ -25,6 +29,12 @@ describe('schema', () => {
       errors: [
         {
           message: 'Unexpected error.',
+          extensions: {
+            /** This error is raised by Graphql.js */
+            originalError: {
+              message: 'Expected null to be a GraphQL schema.',
+            },
+          },
         },
       ],
     })

packages/graphql-yoga/src/plugins/useParserAndValidationCache.ts

@@ -57,6 +57,11 @@ ParserAndValidationCacheOptions): Plugin<{}> {
       setResult,
       // eslint-disable-next-line @typescript-eslint/ban-types
     }): void | AfterValidateHook<{}> {
+      /** No schema no cache */
+      if (schema == null) {
+        return
+      }
+
       if (validationCache !== false) {
         const rulesKey =
           rules?.map((rule: ValidationRule) => rule.name).join(',') || ''