Add useValidationRule() plugin (#2215)

* Add useValidationRule

* Add changeset

* Add a test

* Fix syntax in docs

.changeset/smart-turkeys-leave.md

@@ -0,0 +1,5 @@
+---
+'@envelop/core': patch
+---
+
+feat: add `useValidationRule()` plugin

packages/core/README.md

@@ -13,3 +13,4 @@ https://github.com/n1ru4l/envelop
 - [`useMaskedErrors`](./docs/use-masked-errors.md)
 - [`usePayloadFormatter`](./docs/use-payload-formatter.md)
 - [`useEngine`](./docs/use-engine.md)
+- [`useValidationRule`](./docs/use-validation-rule.md)

packages/core/docs/use-validation-rule.md

@@ -0,0 +1,25 @@
+#### `useValidationRule`
+
+This plugin is the simplest plugin for adding a validation rule to your GraphQL schema. You can
+specify any function that conforms to
+[the `ValidationRule` type](https://github.com/graphql/graphql-js/blob/8a95335f545024c09abfa0f07cc326f73a0e466f/src/validation/ValidationContext.ts#L269).
+
+```ts
+import { execute, parse, specifiedRules, subscribe, validate } from 'graphql'
+import { envelop, useEngine, useValidationRule } from '@envelop/core'
+import { depthLimit } from '@graphile/depth-limit'
+
+const getEnveloped = envelop({
+  plugins: [
+    useEngine({ parse, validate, specifiedRules, execute, subscribe }),
+    useValidationRule(
+      depthLimit({
+        maxDepth: 12,
+        maxListDepth: 4,
+        maxSelfReferentialDepth: 2
+      })
+    )
+    // ... other plugins ...
+  ]
+})
+```

packages/core/src/index.ts

@@ -10,4 +10,5 @@ export * from './plugins/use-extend-context.js';
 export * from './plugins/use-payload-formatter.js';
 export * from './plugins/use-masked-errors.js';
 export * from './plugins/use-engine.js';
+export * from './plugins/use-validation-rule.js';
 export { getDocumentString } from './document-string-map.js';

packages/core/src/plugins/use-validation-rule.ts

@@ -0,0 +1,9 @@
+import { Plugin } from '@envelop/types';
+
+export const useValidationRule = (rule: any): Plugin => {
+  return {
+    onValidate({ addValidationRule }) {
+      addValidationRule(rule);
+    },
+  };
+};

packages/core/test/validate.spec.ts

@@ -1,5 +1,6 @@
 import { GraphQLError, GraphQLSchema, validate, ValidationContext } from 'graphql';
 import { assertSingleExecutionValue, createSpiedPlugin, createTestkit } from '@envelop/testing';
+import { useValidationRule } from '../src/plugins/use-validation-rule.js';
 import { query, schema } from './common.js';
 
 describe('validate', () => {
@@ -126,6 +127,25 @@ describe('validate', () => {
     expect(r.errors![0].message).toBe('Invalid!');
   });
 
+  it('Should allow to add validation rules (reportError, `useValidationRule`)', async () => {
+    const teskit = createTestkit(
+      [
+        useValidationRule((context: any) => {
+          context.reportError(new GraphQLError('Invalid!'));
+          return {};
+        }),
+      ],
+      schema,
+    );
+
+    const r = await teskit.execute(query);
+    assertSingleExecutionValue(r);
+
+    expect(r.errors).toBeDefined();
+    expect(r.errors!.length).toBe(1);
+    expect(r.errors![0].message).toBe('Invalid!');
+  });
+
   it('Should allow to add validation rules (throw)', async () => {
     const teskit = createTestkit(
       [

website/src/lib/plugins.ts

@@ -92,6 +92,17 @@ export const PLUGINS: {
     icon: envelopIcon,
     tags: ['core', 'schema'],
   },
+  {
+    identifier: 'use-validation-rule',
+    title: 'useValidationRule',
+    githubReadme: {
+      repo: 'n1ru4l/envelop',
+      path: 'packages/core/docs/use-validation-rule.md',
+    },
+    npmPackage: '@envelop/core',
+    icon: envelopIcon,
+    tags: ['core', 'utilities'],
+  },
   {
     identifier: 'use-error-handler',
     title: 'useErrorHandler',