From cee50b775f00dd436e16d6e943804dfb4e454fd6 Mon Sep 17 00:00:00 2001
From: "igor.luckenkov" <igor.luchenkov@amplitude.com>
Date: Mon, 24 Oct 2022 09:10:06 +0100
Subject: [PATCH 01/16] added @defer support for requests with multipart/mixed;
 deferSpec=20220824 accept header

---
 index.js           |  94 ++++++++++++++++++++++++++++-
 lib/errors.js      |  14 +++--
 lib/util.js        |  24 +++++++-
 package.json       |   3 +-
 test/directives.js | 145 +++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 269 insertions(+), 11 deletions(-)

diff --git a/index.js b/index.js
index 790a8350..08108b0d 100644
--- a/index.js
+++ b/index.js
@@ -1,5 +1,6 @@
 'use strict'
 
+const Negotiator = require('negotiator')
 const fp = require('fastify-plugin')
 let LRU = require('tiny-lru')
 const routes = require('./lib/routes')
@@ -18,10 +19,10 @@ const {
   extendSchema,
   validate,
   validateSchema,
-  specifiedRules,
-  execute
+  specifiedRules
 } = require('graphql')
 const { buildExecutionContext } = require('graphql/execution/execute')
+const { Readable } = require('stream')
 const queryDepth = require('./lib/queryDepth')
 const buildFederationSchema = require('./lib/federation')
 const { initGateway } = require('./lib/gateway')
@@ -47,6 +48,7 @@ const {
   preExecutionHandler,
   onResolutionHandler
 } = require('./lib/handlers')
+const { executeGraphql, MEDIA_TYPES } = require('./lib/util')
 
 // Required for module bundlers
 // istanbul ignore next
@@ -546,7 +548,7 @@ const plugin = fp(async function (app, opts) {
       return maybeFormatErrors(execution, context)
     }
 
-    const execution = await execute({
+    const execution = await executeGraphql({
       schema: modifiedSchema || fastifyGraphQl.schema,
       document: modifiedDocument || document,
       rootValue: root,
@@ -555,9 +557,95 @@ const plugin = fp(async function (app, opts) {
       operationName
     })
 
+    /* istanbul ignore next */
+    if (execution.initialResult) {
+      const acceptHeader = reply.request.raw.headers.accept
+
+      if (
+        !(
+          acceptHeader &&
+          new Negotiator({
+            headers: { accept: acceptHeader }
+          }).mediaType([
+            // mediaType() will return the first one that matches, so if the client
+            // doesn't include the deferSpec parameter it will match this one here,
+            // which isn't good enough.
+            MEDIA_TYPES.MULTIPART_MIXED_NO_DEFER_SPEC,
+            MEDIA_TYPES.MULTIPART_MIXED_EXPERIMENTAL
+          ]) === MEDIA_TYPES.MULTIPART_MIXED_EXPERIMENTAL
+        )
+      ) {
+        // The client ran an operation that would yield multiple parts, but didn't
+        // specify `accept: multipart/mixed`. We return an error.
+        throw new Error(
+          'Mercurius server received an operation that uses incremental delivery ' +
+          '(@defer or @stream), but the client does not accept multipart/mixed ' +
+          'HTTP responses. To enable incremental delivery support, add the HTTP ' +
+          "header 'Accept: multipart/mixed; deferSpec=20220824'.",
+          // Use 406 Not Accepted TODO
+          { extensions: { http: { status: 406 } } }
+        )
+      }
+
+      reply.header('content-type', 'multipart/mixed; boundary="-"; deferSpec=20220824')
+
+      return Readable.from(
+        writeMultipartBody(
+          execution.initialResult,
+          execution.subsequentResults
+        )
+      )
+    }
+
     return maybeFormatErrors(execution, context)
   }
 
+  /* istanbul ignore next */
+  async function * writeMultipartBody (initialResult, subsequentResults) {
+    yield `\r\n---\r\ncontent-type: application/json; charset=utf-8\r\n\r\n${JSON.stringify(
+      orderInitialIncrementalExecutionResultFields(initialResult)
+    )}\r\n---${initialResult.hasNext ? '' : '--'}\r\n`
+
+    for await (const result of subsequentResults) {
+      yield `content-type: application/json; charset=utf-8\r\n\r\n${JSON.stringify(
+        orderSubsequentIncrementalExecutionResultFields(result)
+      )}\r\n---${result.hasNext ? '' : '--'}\r\n`
+    }
+  }
+
+  /* istanbul ignore next */
+  function orderInitialIncrementalExecutionResultFields (result) {
+    return {
+      hasNext: result.hasNext,
+      errors: result.errors,
+      data: result.data,
+      incremental: orderIncrementalResultFields(result.incremental),
+      extensions: result.extensions
+    }
+  }
+
+  /* istanbul ignore next */
+  function orderSubsequentIncrementalExecutionResultFields (result) {
+    return {
+      hasNext: result.hasNext,
+      incremental: orderIncrementalResultFields(result.incremental),
+      extensions: result.extensions
+    }
+  }
+
+  /* istanbul ignore next */
+  function orderIncrementalResultFields (incremental) {
+    return incremental?.map((i) => ({
+      hasNext: i.hasNext,
+      errors: i.errors,
+      path: i.path,
+      label: i.label,
+      data: i.data,
+      items: i.items,
+      extensions: i.extensions
+    }))
+  }
+
   async function maybeFormatErrors (execution, context) {
     execution = addErrorsToExecutionResult(execution, context.errors)
 
diff --git a/lib/errors.js b/lib/errors.js
index b6f7a31b..1cfb5c79 100644
--- a/lib/errors.js
+++ b/lib/errors.js
@@ -35,12 +35,14 @@ function toGraphQLError (err) {
 
   const gqlError = new GraphQLError(
     err.message,
-    err.nodes,
-    err.source,
-    err.positions,
-    err.path,
-    err,
-    err.extensions
+    {
+      nodes: err.nodes,
+      source: err.source,
+      positions: err.positions,
+      path: err.path,
+      originalError: err,
+      extensions: err.extensions
+    }
   )
 
   gqlError.locations = err.locations
diff --git a/lib/util.js b/lib/util.js
index 8a836203..de348228 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -1,5 +1,8 @@
 'use strict'
 
+const { execute } = require('graphql')
+const { experimentalExecuteIncrementally } = require('graphql/execution')
+
 function hasDirective (directiveName, node) {
   if (!node.directives || node.directives.length < 1) {
     return false
@@ -23,7 +26,26 @@ function hasExtensionDirective (node) {
   }
 }
 
+const canUseIncrementalExecution = !!require('graphql/execution').experimentalExecuteIncrementally
+
+// istanbul ignore next
+function executeGraphql (args) {
+  if (canUseIncrementalExecution) {
+    return experimentalExecuteIncrementally(args)
+  }
+
+  return execute(args)
+}
+
+const MEDIA_TYPES = {
+  MULTIPART_MIXED_NO_DEFER_SPEC: 'multipart/mixed',
+  MULTIPART_MIXED_EXPERIMENTAL: 'multipart/mixed; deferSpec=20220824'
+}
+
 module.exports = {
   hasDirective,
-  hasExtensionDirective
+  hasExtensionDirective,
+  canUseIncrementalExecution,
+  executeGraphql,
+  MEDIA_TYPES
 }
diff --git a/package.json b/package.json
index 9611f408..bbd1857d 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "mercurius",
-  "version": "11.1.0",
+  "version": "11.2.0",
   "description": "Fastify GraphQL adapter with gateway and subscription support",
   "main": "index.js",
   "types": "index.d.ts",
@@ -64,6 +64,7 @@
     "graphql": "^16.0.0",
     "graphql-jit": "^0.7.3",
     "mqemitter": "^5.0.0",
+    "negotiator": "^0.6.3",
     "p-map": "^4.0.0",
     "readable-stream": "^4.0.0",
     "safe-stable-stringify": "^2.3.0",
diff --git a/test/directives.js b/test/directives.js
index 245d9b7f..c23bd923 100644
--- a/test/directives.js
+++ b/test/directives.js
@@ -14,6 +14,7 @@ const {
   getResolversFromSchema
 } = require('@graphql-tools/utils')
 const buildFederationSchema = require('../lib/federation')
+const { canUseIncrementalExecution } = require('../lib/util')
 
 class ValidationError extends Error {
   constructor (message, extensions) {
@@ -962,3 +963,147 @@ type User {
     }
   })
 })
+
+if (canUseIncrementalExecution) {
+  const schema = `
+    directive @defer(
+      if: Boolean! = true
+      label: String
+    ) on FRAGMENT_SPREAD | INLINE_FRAGMENT
+
+    type Query {
+      allProducts: [Product!]!
+    }
+    
+    type Product {
+      delivery: DeliveryEstimates!
+      sku: String!
+      id: ID!
+    }
+    
+    type DeliveryEstimates {
+      estimatedDelivery: String!
+      fastestDelivery: String!
+    }`
+
+  const allProducts = new Array(1).fill(0).map((_, index) => ({
+    id: `${index}`,
+    sku: 'sku'
+  }))
+
+  const resolvers = {
+    Query: {
+      allProducts: () => {
+        return allProducts
+      }
+    },
+    Product: {
+      delivery: () => {
+        return {
+          estimatedDelivery: '25.01.2000',
+          fastestDelivery: '25.01.2000'
+        }
+      }
+    }
+  }
+
+  const query = `
+    query deferVariation {
+      allProducts {
+        delivery {
+          ...MyFragment @defer
+        }
+        sku
+        id
+      }
+    }
+  
+    fragment MyFragment on DeliveryEstimates {
+      estimatedDelivery
+      fastestDelivery
+    }
+  `
+
+  test('errors with @defer when used with wrong "accept" header', async t => {
+    const wrongAcceptValues = [
+      '',
+      'application/json',
+      'multipart/mixed',
+      'multipart/mixed; deferSpec=12345'
+    ]
+
+    for (const accept of wrongAcceptValues) {
+      const app = Fastify()
+      await app.register(mercurius, { schema, resolvers, graphiql: true })
+
+      const res = await app.inject({
+        method: 'POST',
+        url: '/graphql',
+        headers: {
+          'content-type': 'application/json',
+          accept
+        },
+        body: JSON.stringify({ query })
+      })
+
+      t.match(res, {
+        statusCode: 200,
+        body: JSON.stringify({
+          data: null,
+          errors: [{
+            message: "Mercurius server received an operation that uses incremental delivery (@defer or @stream), but the client does not accept multipart/mixed HTTP responses. To enable incremental delivery support, add the HTTP header 'Accept: multipart/mixed; deferSpec=20220824'."
+          }]
+        })
+      })
+
+      await app.close()
+    }
+
+    t.end()
+  })
+
+  test('works with @defer when used with correct "accept" header', async t => {
+    const correctAcceptValues = [
+      'multipart/mixed; deferSpec=20220824',
+      'multipart/mixed; deferSpec=20220824, application/json',
+      'application/json, multipart/mixed; deferSpec=20220824'
+    ]
+
+    for (const accept of correctAcceptValues) {
+      const app = Fastify()
+      await app.register(mercurius, { schema, resolvers, graphiql: true })
+
+      const res = await app.inject({
+        method: 'POST',
+        url: '/graphql',
+        headers: {
+          'content-type': 'application/json',
+          accept
+        },
+        body: JSON.stringify({ query })
+      })
+
+      t.match(res, {
+        statusCode: 200,
+        headers: {
+          'content-type': 'multipart/mixed; boundary="-"; deferSpec=20220824'
+        },
+        body: `\r
+---\r
+content-type: application/json; charset=utf-8\r
+\r
+{"hasNext":true,"data":{"allProducts":[{"delivery":{},"sku":"sku","id":"0"}]}}\r
+---\r
+content-type: application/json; charset=utf-8\r
+\r
+{"hasNext":false,"incremental":[{"path":["allProducts",0,"delivery"],"data":{"estimatedDelivery":"25.01.2000","fastestDelivery":"25.01.2000"}}]}\r
+-----\r
+`
+      })
+
+      await app.close()
+    }
+
+    t.end()
+  })
+}

From 4ad38b468bdc1d632190bf96c35fb2be493165f4 Mon Sep 17 00:00:00 2001
From: "igor.luckenkov" <igor.luchenkov@amplitude.com>
Date: Wed, 26 Oct 2022 10:02:59 +0100
Subject: [PATCH 02/16] reverted mercurius version bump, moved @defer tests to
 their own file

---
 package.json       |   2 +-
 test/defer.js      | 146 +++++++++++++++++++++++++++++++++++++++++++++
 test/directives.js | 145 --------------------------------------------
 3 files changed, 147 insertions(+), 146 deletions(-)
 create mode 100644 test/defer.js

diff --git a/package.json b/package.json
index bbd1857d..36f17bba 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "mercurius",
-  "version": "11.2.0",
+  "version": "11.1.0",
   "description": "Fastify GraphQL adapter with gateway and subscription support",
   "main": "index.js",
   "types": "index.d.ts",
diff --git a/test/defer.js b/test/defer.js
new file mode 100644
index 00000000..9e2e3e46
--- /dev/null
+++ b/test/defer.js
@@ -0,0 +1,146 @@
+const { test } = require('tap')
+const Fastify = require('fastify')
+const mercurius = require('../index')
+const { canUseIncrementalExecution } = require('../lib/util')
+
+if (canUseIncrementalExecution) {
+  const schema = `
+    directive @defer(
+      if: Boolean! = true
+      label: String
+    ) on FRAGMENT_SPREAD | INLINE_FRAGMENT
+
+    type Query {
+      allProducts: [Product!]!
+    }
+    
+    type Product {
+      delivery: DeliveryEstimates!
+      sku: String!
+      id: ID!
+    }
+    
+    type DeliveryEstimates {
+      estimatedDelivery: String!
+      fastestDelivery: String!
+    }`
+
+  const allProducts = new Array(1).fill(0).map((_, index) => ({
+    id: `${index}`,
+    sku: 'sku'
+  }))
+
+  const resolvers = {
+    Query: {
+      allProducts: () => {
+        return allProducts
+      }
+    },
+    Product: {
+      delivery: () => {
+        return {
+          estimatedDelivery: '25.01.2000',
+          fastestDelivery: '25.01.2000'
+        }
+      }
+    }
+  }
+
+  const query = `
+    query deferVariation {
+      allProducts {
+        delivery {
+          ...MyFragment @defer
+        }
+        sku
+        id
+      }
+    }
+  
+    fragment MyFragment on DeliveryEstimates {
+      estimatedDelivery
+      fastestDelivery
+    }
+  `
+
+  const wrongAcceptValues = [
+    '',
+    'application/json',
+    'multipart/mixed',
+    'multipart/mixed; deferSpec=12345'
+  ]
+
+  for (const accept of wrongAcceptValues) {
+    test('errors with @defer when used with wrong "accept" header', async t => {
+      const app = Fastify()
+      await app.register(mercurius, { schema, resolvers, graphiql: true })
+
+      const res = await app.inject({
+        method: 'POST',
+        url: '/graphql',
+        headers: {
+          'content-type': 'application/json',
+          accept
+        },
+        body: JSON.stringify({ query })
+      })
+
+      t.match(res, {
+        statusCode: 200,
+        body: JSON.stringify({
+          data: null,
+          errors: [{
+            message: "Mercurius server received an operation that uses incremental delivery (@defer or @stream), but the client does not accept multipart/mixed HTTP responses. To enable incremental delivery support, add the HTTP header 'Accept: multipart/mixed; deferSpec=20220824'."
+          }]
+        })
+      })
+
+      await app.close()
+      t.end()
+    })
+  }
+
+  const correctAcceptValues = [
+    'multipart/mixed; deferSpec=20220824',
+    'multipart/mixed; deferSpec=20220824, application/json',
+    'application/json, multipart/mixed; deferSpec=20220824'
+  ]
+
+  for (const accept of correctAcceptValues) {
+    test('works with @defer when used with correct "accept" header', async t => {
+      const app = Fastify()
+      await app.register(mercurius, { schema, resolvers, graphiql: true })
+
+      const res = await app.inject({
+        method: 'POST',
+        url: '/graphql',
+        headers: {
+          'content-type': 'application/json',
+          accept
+        },
+        body: JSON.stringify({ query })
+      })
+
+      t.match(res, {
+        statusCode: 200,
+        headers: {
+          'content-type': 'multipart/mixed; boundary="-"; deferSpec=20220824'
+        },
+        body: `\r
+---\r
+content-type: application/json; charset=utf-8\r
+\r
+{"hasNext":true,"data":{"allProducts":[{"delivery":{},"sku":"sku","id":"0"}]}}\r
+---\r
+content-type: application/json; charset=utf-8\r
+\r
+{"hasNext":false,"incremental":[{"path":["allProducts",0,"delivery"],"data":{"estimatedDelivery":"25.01.2000","fastestDelivery":"25.01.2000"}}]}\r
+-----\r
+`
+      })
+
+      await app.close()
+      t.end()
+    })
+  }
+}
diff --git a/test/directives.js b/test/directives.js
index c23bd923..245d9b7f 100644
--- a/test/directives.js
+++ b/test/directives.js
@@ -14,7 +14,6 @@ const {
   getResolversFromSchema
 } = require('@graphql-tools/utils')
 const buildFederationSchema = require('../lib/federation')
-const { canUseIncrementalExecution } = require('../lib/util')
 
 class ValidationError extends Error {
   constructor (message, extensions) {
@@ -963,147 +962,3 @@ type User {
     }
   })
 })
-
-if (canUseIncrementalExecution) {
-  const schema = `
-    directive @defer(
-      if: Boolean! = true
-      label: String
-    ) on FRAGMENT_SPREAD | INLINE_FRAGMENT
-
-    type Query {
-      allProducts: [Product!]!
-    }
-    
-    type Product {
-      delivery: DeliveryEstimates!
-      sku: String!
-      id: ID!
-    }
-    
-    type DeliveryEstimates {
-      estimatedDelivery: String!
-      fastestDelivery: String!
-    }`
-
-  const allProducts = new Array(1).fill(0).map((_, index) => ({
-    id: `${index}`,
-    sku: 'sku'
-  }))
-
-  const resolvers = {
-    Query: {
-      allProducts: () => {
-        return allProducts
-      }
-    },
-    Product: {
-      delivery: () => {
-        return {
-          estimatedDelivery: '25.01.2000',
-          fastestDelivery: '25.01.2000'
-        }
-      }
-    }
-  }
-
-  const query = `
-    query deferVariation {
-      allProducts {
-        delivery {
-          ...MyFragment @defer
-        }
-        sku
-        id
-      }
-    }
-  
-    fragment MyFragment on DeliveryEstimates {
-      estimatedDelivery
-      fastestDelivery
-    }
-  `
-
-  test('errors with @defer when used with wrong "accept" header', async t => {
-    const wrongAcceptValues = [
-      '',
-      'application/json',
-      'multipart/mixed',
-      'multipart/mixed; deferSpec=12345'
-    ]
-
-    for (const accept of wrongAcceptValues) {
-      const app = Fastify()
-      await app.register(mercurius, { schema, resolvers, graphiql: true })
-
-      const res = await app.inject({
-        method: 'POST',
-        url: '/graphql',
-        headers: {
-          'content-type': 'application/json',
-          accept
-        },
-        body: JSON.stringify({ query })
-      })
-
-      t.match(res, {
-        statusCode: 200,
-        body: JSON.stringify({
-          data: null,
-          errors: [{
-            message: "Mercurius server received an operation that uses incremental delivery (@defer or @stream), but the client does not accept multipart/mixed HTTP responses. To enable incremental delivery support, add the HTTP header 'Accept: multipart/mixed; deferSpec=20220824'."
-          }]
-        })
-      })
-
-      await app.close()
-    }
-
-    t.end()
-  })
-
-  test('works with @defer when used with correct "accept" header', async t => {
-    const correctAcceptValues = [
-      'multipart/mixed; deferSpec=20220824',
-      'multipart/mixed; deferSpec=20220824, application/json',
-      'application/json, multipart/mixed; deferSpec=20220824'
-    ]
-
-    for (const accept of correctAcceptValues) {
-      const app = Fastify()
-      await app.register(mercurius, { schema, resolvers, graphiql: true })
-
-      const res = await app.inject({
-        method: 'POST',
-        url: '/graphql',
-        headers: {
-          'content-type': 'application/json',
-          accept
-        },
-        body: JSON.stringify({ query })
-      })
-
-      t.match(res, {
-        statusCode: 200,
-        headers: {
-          'content-type': 'multipart/mixed; boundary="-"; deferSpec=20220824'
-        },
-        body: `\r
----\r
-content-type: application/json; charset=utf-8\r
-\r
-{"hasNext":true,"data":{"allProducts":[{"delivery":{},"sku":"sku","id":"0"}]}}\r
----\r
-content-type: application/json; charset=utf-8\r
-\r
-{"hasNext":false,"incremental":[{"path":["allProducts",0,"delivery"],"data":{"estimatedDelivery":"25.01.2000","fastestDelivery":"25.01.2000"}}]}\r
------\r
-`
-      })
-
-      await app.close()
-    }
-
-    t.end()
-  })
-}

From 08ee6d2ff7526d3ba27a3a1319cd4fefbf9a4904 Mon Sep 17 00:00:00 2001
From: "igor.luckenkov" <igor.luchenkov@amplitude.com>
Date: Wed, 26 Oct 2022 10:17:17 +0100
Subject: [PATCH 03/16] remove 'Mercurius' from the error message about wrong
 accept header, removed unnecessary status code in the error

---
 index.js      | 6 ++----
 test/defer.js | 2 +-
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/index.js b/index.js
index 08108b0d..fd3fee97 100644
--- a/index.js
+++ b/index.js
@@ -578,12 +578,10 @@ const plugin = fp(async function (app, opts) {
         // The client ran an operation that would yield multiple parts, but didn't
         // specify `accept: multipart/mixed`. We return an error.
         throw new Error(
-          'Mercurius server received an operation that uses incremental delivery ' +
+          'Server received an operation that uses incremental delivery ' +
           '(@defer or @stream), but the client does not accept multipart/mixed ' +
           'HTTP responses. To enable incremental delivery support, add the HTTP ' +
-          "header 'Accept: multipart/mixed; deferSpec=20220824'.",
-          // Use 406 Not Accepted TODO
-          { extensions: { http: { status: 406 } } }
+          "header 'Accept: multipart/mixed; deferSpec=20220824'."
         )
       }
 
diff --git a/test/defer.js b/test/defer.js
index 9e2e3e46..89b0de31 100644
--- a/test/defer.js
+++ b/test/defer.js
@@ -90,7 +90,7 @@ if (canUseIncrementalExecution) {
         body: JSON.stringify({
           data: null,
           errors: [{
-            message: "Mercurius server received an operation that uses incremental delivery (@defer or @stream), but the client does not accept multipart/mixed HTTP responses. To enable incremental delivery support, add the HTTP header 'Accept: multipart/mixed; deferSpec=20220824'."
+            message: "Server received an operation that uses incremental delivery (@defer or @stream), but the client does not accept multipart/mixed HTTP responses. To enable incremental delivery support, add the HTTP header 'Accept: multipart/mixed; deferSpec=20220824'."
           }]
         })
       })

From 35fdb02853559da512278b23c331e3e2ad8818ec Mon Sep 17 00:00:00 2001
From: "igor.luckenkov" <igor.luchenkov@amplitude.com>
Date: Wed, 26 Oct 2022 19:31:47 +0100
Subject: [PATCH 04/16] bump graphql to 17.0.0-alpha.2

---
 package.json | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/package.json b/package.json
index 36f17bba..6f66a1df 100644
--- a/package.json
+++ b/package.json
@@ -27,7 +27,7 @@
   },
   "homepage": "https://mercurius.dev",
   "peerDependencies": {
-    "graphql": "^16.0.0"
+    "graphql": "^17.0.0-alpha.2"
   },
   "devDependencies": {
     "@graphql-tools/merge": "^8.0.0",
@@ -61,7 +61,7 @@
     "@fastify/websocket": "^7.0.0",
     "events.on": "^1.0.1",
     "fastify-plugin": "^4.2.0",
-    "graphql": "^16.0.0",
+    "graphql": "^17.0.0-alpha.2",
     "graphql-jit": "^0.7.3",
     "mqemitter": "^5.0.0",
     "negotiator": "^0.6.3",

From d41fff63bcc083fd008b63d03e20ddddae007c19 Mon Sep 17 00:00:00 2001
From: "igor.luckenkov" <igor.luchenkov@amplitude.com>
Date: Wed, 26 Oct 2022 19:32:24 +0100
Subject: [PATCH 05/16] moved missing multipart accept header error into
 errors.js

---
 index.js      | 10 +++-------
 lib/errors.js |  4 ++++
 test/defer.js |  4 ++--
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/index.js b/index.js
index fd3fee97..ca6337a1 100644
--- a/index.js
+++ b/index.js
@@ -38,7 +38,8 @@ const {
   MER_ERR_GQL_VALIDATION,
   MER_ERR_INVALID_OPTS,
   MER_ERR_METHOD_NOT_ALLOWED,
-  MER_ERR_INVALID_METHOD
+  MER_ERR_INVALID_METHOD,
+  MER_ERR_INVALID_MULTIPART_ACCEPT_HEADER
 } = require('./lib/errors')
 const { Hooks, assignLifeCycleHooksToContext } = require('./lib/hooks')
 const { kLoaders, kFactory, kSubscriptionFactory, kHooks } = require('./lib/symbols')
@@ -577,12 +578,7 @@ const plugin = fp(async function (app, opts) {
       ) {
         // The client ran an operation that would yield multiple parts, but didn't
         // specify `accept: multipart/mixed`. We return an error.
-        throw new Error(
-          'Server received an operation that uses incremental delivery ' +
-          '(@defer or @stream), but the client does not accept multipart/mixed ' +
-          'HTTP responses. To enable incremental delivery support, add the HTTP ' +
-          "header 'Accept: multipart/mixed; deferSpec=20220824'."
-        )
+        throw new MER_ERR_INVALID_MULTIPART_ACCEPT_HEADER()
       }
 
       reply.header('content-type', 'multipart/mixed; boundary="-"; deferSpec=20220824')
diff --git a/lib/errors.js b/lib/errors.js
index 1cfb5c79..e55242ee 100644
--- a/lib/errors.js
+++ b/lib/errors.js
@@ -139,6 +139,10 @@ const errors = {
     'Method not allowed',
     405
   ),
+  MER_ERR_INVALID_MULTIPART_ACCEPT_HEADER: createError(
+    'MER_ERR_INVALID_MULTIPART_ACCEPT_HEADER',
+    'Server received an operation that uses incremental delivery (@defer or @stream), but the client does not accept multipart/mixed HTTP responses. To enable incremental delivery support, add the HTTP header "Accept: multipart/mixed; deferSpec=20220824".'
+  ),
   /**
    * General graphql errors
    */
diff --git a/test/defer.js b/test/defer.js
index 89b0de31..eb2a8a65 100644
--- a/test/defer.js
+++ b/test/defer.js
@@ -86,11 +86,11 @@ if (canUseIncrementalExecution) {
       })
 
       t.match(res, {
-        statusCode: 200,
+        statusCode: 500,
         body: JSON.stringify({
           data: null,
           errors: [{
-            message: "Server received an operation that uses incremental delivery (@defer or @stream), but the client does not accept multipart/mixed HTTP responses. To enable incremental delivery support, add the HTTP header 'Accept: multipart/mixed; deferSpec=20220824'."
+            message: 'Server received an operation that uses incremental delivery (@defer or @stream), but the client does not accept multipart/mixed HTTP responses. To enable incremental delivery support, add the HTTP header "Accept: multipart/mixed; deferSpec=20220824".'
           }]
         })
       })

From 274c5bc6d35f7dd1a1e0104b163d89b8ab782def Mon Sep 17 00:00:00 2001
From: "igor.luckenkov" <igor.luchenkov@amplitude.com>
Date: Wed, 26 Oct 2022 19:50:51 +0100
Subject: [PATCH 06/16] added opts.defer: boolean to enable @defer directive

---
 index.js      | 12 ++++++++++++
 test/defer.js | 36 +++++++++++++++++++++++++++++-------
 2 files changed, 41 insertions(+), 7 deletions(-)

diff --git a/index.js b/index.js
index ca6337a1..6c96c425 100644
--- a/index.js
+++ b/index.js
@@ -190,6 +190,18 @@ const plugin = fp(async function (app, opts) {
     })
   }
 
+  if (opts.defer) {
+    schema = extendSchema(
+      schema,
+      parse(`
+        directive @defer(
+          if: Boolean! = true
+          label: String
+        ) on FRAGMENT_SPREAD | INLINE_FRAGMENT
+      `)
+    )
+  }
+
   fastifyGraphQl.schema = schema
 
   app.addHook('onReady', async function () {
diff --git a/test/defer.js b/test/defer.js
index eb2a8a65..8bf05fd8 100644
--- a/test/defer.js
+++ b/test/defer.js
@@ -5,11 +5,6 @@ const { canUseIncrementalExecution } = require('../lib/util')
 
 if (canUseIncrementalExecution) {
   const schema = `
-    directive @defer(
-      if: Boolean! = true
-      label: String
-    ) on FRAGMENT_SPREAD | INLINE_FRAGMENT
-
     type Query {
       allProducts: [Product!]!
     }
@@ -70,10 +65,37 @@ if (canUseIncrementalExecution) {
     'multipart/mixed; deferSpec=12345'
   ]
 
+  test('errors with @defer when opts.defer is not true', async t => {
+    const app = Fastify()
+    await app.register(mercurius, { schema, resolvers, graphiql: true })
+
+    const res = await app.inject({
+      method: 'POST',
+      url: '/graphql',
+      headers: {
+        'content-type': 'application/json'
+      },
+      body: JSON.stringify({ query })
+    })
+
+    t.match(res, {
+      statusCode: 400,
+      body: JSON.stringify({
+        data: null,
+        errors: [{
+          message: 'Unknown directive "@defer".', locations: [{ line: 5, column: 25 }]
+        }]
+      })
+    })
+
+    await app.close()
+    t.end()
+  })
+
   for (const accept of wrongAcceptValues) {
     test('errors with @defer when used with wrong "accept" header', async t => {
       const app = Fastify()
-      await app.register(mercurius, { schema, resolvers, graphiql: true })
+      await app.register(mercurius, { schema, resolvers, graphiql: true, defer: true })
 
       const res = await app.inject({
         method: 'POST',
@@ -109,7 +131,7 @@ if (canUseIncrementalExecution) {
   for (const accept of correctAcceptValues) {
     test('works with @defer when used with correct "accept" header', async t => {
       const app = Fastify()
-      await app.register(mercurius, { schema, resolvers, graphiql: true })
+      await app.register(mercurius, { schema, resolvers, graphiql: true, defer: true })
 
       const res = await app.inject({
         method: 'POST',

From 3e3ca7772e6e1e38a70f74f9cf2b63aabc0d1462 Mon Sep 17 00:00:00 2001
From: "igor.luckenkov" <igor.luchenkov@amplitude.com>
Date: Wed, 26 Oct 2022 20:02:57 +0100
Subject: [PATCH 07/16] use @fastify/accepts instead of Negotiator package

---
 index.js     | 10 ++++------
 package.json |  2 +-
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/index.js b/index.js
index 6c96c425..99b2a19b 100644
--- a/index.js
+++ b/index.js
@@ -1,6 +1,5 @@
 'use strict'
 
-const Negotiator = require('negotiator')
 const fp = require('fastify-plugin')
 let LRU = require('tiny-lru')
 const routes = require('./lib/routes')
@@ -191,6 +190,8 @@ const plugin = fp(async function (app, opts) {
   }
 
   if (opts.defer) {
+    app.register(require('@fastify/accepts'))
+
     schema = extendSchema(
       schema,
       parse(`
@@ -572,14 +573,11 @@ const plugin = fp(async function (app, opts) {
 
     /* istanbul ignore next */
     if (execution.initialResult) {
-      const acceptHeader = reply.request.raw.headers.accept
+      const accept = reply.request.accepts() // Accepts object
 
       if (
         !(
-          acceptHeader &&
-          new Negotiator({
-            headers: { accept: acceptHeader }
-          }).mediaType([
+          accept.negotiator.mediaType([
             // mediaType() will return the first one that matches, so if the client
             // doesn't include the deferSpec parameter it will match this one here,
             // which isn't good enough.
diff --git a/package.json b/package.json
index 6f66a1df..6d94e373 100644
--- a/package.json
+++ b/package.json
@@ -56,6 +56,7 @@
     "wait-on": "^6.0.0"
   },
   "dependencies": {
+    "@fastify/accepts": "^4.0.1",
     "@fastify/error": "^3.0.0",
     "@fastify/static": "^6.0.0",
     "@fastify/websocket": "^7.0.0",
@@ -64,7 +65,6 @@
     "graphql": "^17.0.0-alpha.2",
     "graphql-jit": "^0.7.3",
     "mqemitter": "^5.0.0",
-    "negotiator": "^0.6.3",
     "p-map": "^4.0.0",
     "readable-stream": "^4.0.0",
     "safe-stable-stringify": "^2.3.0",

From 2b3c25a400199df25aff25ca19037a6f4922913a Mon Sep 17 00:00:00 2001
From: "igor.luckenkov" <igor.luchenkov@amplitude.com>
Date: Wed, 26 Oct 2022 21:07:42 +0100
Subject: [PATCH 08/16] add @defer test with undici.fetch

---
 test/defer.js | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/test/defer.js b/test/defer.js
index 8bf05fd8..2d70ef81 100644
--- a/test/defer.js
+++ b/test/defer.js
@@ -1,5 +1,6 @@
 const { test } = require('tap')
 const Fastify = require('fastify')
+const { fetch } = require('undici')
 const mercurius = require('../index')
 const { canUseIncrementalExecution } = require('../lib/util')
 
@@ -165,4 +166,46 @@ content-type: application/json; charset=utf-8\r
       t.end()
     })
   }
+
+  test('returns stream when using undici.fetch with @defer', async t => {
+    const app = Fastify()
+    await app.register(mercurius, { schema, resolvers, graphiql: true, defer: true })
+    const url = await app.listen({ port: 0 })
+
+    const res = await fetch(`${url}/graphql`, {
+      method: 'POST',
+      headers: {
+        'content-type': 'application/json',
+        accept: 'multipart/mixed; deferSpec=20220824'
+      },
+      body: JSON.stringify({ query })
+    })
+
+    const reader = res.body.getReader()
+    const { value } = await reader.read()
+    const result = new TextDecoder('utf-8').decode(value)
+
+    t.same(result, `\r
+---\r
+content-type: application/json; charset=utf-8\r
+\r
+{"hasNext":true,"data":{"allProducts":[{"delivery":{},"sku":"sku","id":"0"}]}}\r
+---\r
+content-type: application/json; charset=utf-8\r
+\r
+{"hasNext":false,"incremental":[{"path":["allProducts",0,"delivery"],"data":{"estimatedDelivery":"25.01.2000","fastestDelivery":"25.01.2000"}}]}\r
+-----\r
+`)
+
+    t.same(res.status, 200)
+    t.same(res.headers.get('content-type'), 'multipart/mixed; boundary="-"; deferSpec=20220824')
+
+    t.teardown(async () => {
+      await reader.releaseLock()
+      app.close()
+      process.exit()
+    })
+
+    t.end()
+  })
 }

From 369457ea9b1822d6f1f65234c48bf3a6cd6bd61c Mon Sep 17 00:00:00 2001
From: Bartek Igielski <igloczek@gmail.com>
Date: Wed, 2 Nov 2022 12:11:37 +0100
Subject: [PATCH 09/16] Add space between merged SDLs to fix merging errors
 (#899)

* Add space between merged SDLs to fix merging errors

* Add unit tests for schema merging
---
 lib/gateway/build-gateway.js |  6 ++--
 test/gateway/schema.js       | 59 ++++++++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+), 3 deletions(-)

diff --git a/lib/gateway/build-gateway.js b/lib/gateway/build-gateway.js
index bdac04c7..758792f3 100644
--- a/lib/gateway/build-gateway.js
+++ b/lib/gateway/build-gateway.js
@@ -313,7 +313,7 @@ async function buildGateway (gatewayOpts, app) {
     throw new MER_ERR_GQL_GATEWAY_INIT('No valid service SDLs were provided')
   }
 
-  const schema = buildFederatedSchema(serviceSDLs.join(''), true)
+  const schema = buildFederatedSchema(serviceSDLs.join(' '), true)
 
   const typeToServiceMap = {}
   const typeFieldsToService = {}
@@ -419,7 +419,7 @@ async function buildGateway (gatewayOpts, app) {
     async refresh (isRetry) {
       const failedMandatoryServices = []
       if (this._serviceSDLs === undefined) {
-        this._serviceSDLs = serviceSDLs.join('')
+        this._serviceSDLs = serviceSDLs.join(' ')
       }
 
       const $refreshResult = await Promise.allSettled(
@@ -458,7 +458,7 @@ async function buildGateway (gatewayOpts, app) {
 
       const _serviceSDLs = Object.values(serviceMap)
         .map((service) => service.schemaDefinition)
-        .join('')
+        .join(' ')
 
       if (this._serviceSDLs === _serviceSDLs) {
         return null
diff --git a/test/gateway/schema.js b/test/gateway/schema.js
index 13bdecd7..e2fce8fe 100644
--- a/test/gateway/schema.js
+++ b/test/gateway/schema.js
@@ -302,6 +302,65 @@ test('It builds the gateway schema correctly', async (t) => {
   })
 })
 
+test('Should merge schemas correctly', async (t) => {
+  const [helloService, helloServicePort] = await createService(
+    t,
+    'extend type Query { hello: String } directive @customDirective on FIELD_DEFINITION',
+    { Query: { hello: () => 'World' } }
+  )
+
+  const [worldService, worldServicePort] = await createService(
+    t,
+    'extend type Query { world: String }',
+    { Query: { world: () => 'Hello' } }
+  )
+
+  const gateway = Fastify()
+
+  t.teardown(async () => {
+    await gateway.close()
+    await helloService.close()
+    await worldService.close()
+  })
+
+  gateway.register(GQL, {
+    gateway: {
+      services: [{
+        name: 'hello',
+        url: `http://localhost:${helloServicePort}/graphql`
+      }, {
+        name: 'world',
+        url: `http://localhost:${worldServicePort}/graphql`
+      }]
+    }
+  })
+
+  const query = `
+    query {
+      hello
+      world
+    }
+  `
+
+  const res = await gateway.inject({
+    method: 'POST',
+    headers: {
+      'content-type': 'application/json'
+    },
+    url: '/graphql',
+    body: JSON.stringify({
+      query
+    })
+  })
+
+  t.same(JSON.parse(res.body), {
+    data: {
+      hello: 'World',
+      world: 'Hello'
+    }
+  })
+})
+
 test('It support variable inside nested arguments', async (t) => {
   const user = {
     id: 'u1',

From 780c668742109d9375ab33d89433f52af1ed5980 Mon Sep 17 00:00:00 2001
From: Igor Luchenkov <iluchenkov@gmail.com>
Date: Wed, 2 Nov 2022 11:12:13 +0000
Subject: [PATCH 10/16] Explicitly say in the docs that JIT is disabled by
 default (#901)

---
 docs/api/options.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/docs/api/options.md b/docs/api/options.md
index 3f89d568..cf57686e 100644
--- a/docs/api/options.md
+++ b/docs/api/options.md
@@ -52,6 +52,7 @@
 
 - `jit`: Integer. The minimum number of execution a query needs to be
   executed before being jit'ed.
+  - Default: `0`, jit is disabled.
 - `routes`: boolean. Serves the Default: `true`. A graphql endpoint is
   exposed at `/graphql`.
 - `path`: string. Change default graphql `/graphql` route to another one.

From b4d70fc50537273a12fbba337c1b7b4a1e08a371 Mon Sep 17 00:00:00 2001
From: Davide Fiorello <davide@codeflyer.com>
Date: Wed, 2 Nov 2022 15:45:25 +0100
Subject: [PATCH 11/16] feat: add types for object in graphiql configuration
 (#907)

* feat: add types for object in graphiql configuration

* feat: add test to types
---
 index.d.ts          | 32 ++++++++++++++++++++++++++++++--
 test/types/index.ts | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/index.d.ts b/index.d.ts
index 39df195b..5673216c 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -437,12 +437,40 @@ export interface MercuriusSchemaOptions {
   schemaTransforms?: ((originalSchema: GraphQLSchema) => GraphQLSchema) | Array<(originalSchema: GraphQLSchema) => GraphQLSchema>;
 }
 
+export interface MercuriusGraphiQLOptions {
+  /**
+   * Expose the graphiql app, default `true`
+   */
+  enabled?: boolean;
+  /**
+   * The list of plugin to add to GraphiQL
+   */
+  plugins?: Array<{
+    /**
+     * The name of the plugin, it should be the same exported in the `umd`
+     */
+    name: string;
+    /**
+     * The props to be passed to the plugin
+     */
+    props?: Object;
+    /**
+     * The urls of the plugin, it's downloaded at runtime. (eg. https://unpkg.com/myplugin/....)
+     */
+    umdUrl: string;
+    /**
+     * A function name exported by the plugin to read/enrich the fetch response
+     */
+    fetcherWrapper?: string;
+  }>
+}
+
 export interface MercuriusCommonOptions {
   /**
    * Serve GraphiQL on /graphiql if true or 'graphiql' and if routes is true
    */
-  graphiql?: boolean | 'graphiql';
-  ide?: boolean | 'graphiql';
+  graphiql?: boolean | 'graphiql' | MercuriusGraphiQLOptions;
+  ide?: boolean | 'graphiql' | MercuriusGraphiQLOptions;
   /**
    * The minimum number of execution a query needs to be executed before being jit'ed.
    * @default 0 - disabled
diff --git a/test/types/index.ts b/test/types/index.ts
index 175a51c3..3e56828d 100644
--- a/test/types/index.ts
+++ b/test/types/index.ts
@@ -879,3 +879,40 @@ app.graphql.addHook('onResolution', async function (_execution, context) {
   expectType<number | undefined>(context.operationsCount)
   expectType<string>(context.__currentQuery)
 })
+
+// Test graphiql configuration using an object as params
+app.register(mercurius, { schema, resolvers, graphiql: { plugins: [] } })
+
+app.register(mercurius, { schema, resolvers, ide: { enabled: false } })
+
+app.register(mercurius, {
+  schema,
+  resolvers,
+  graphiql: {
+    enabled: true,
+    plugins: [
+      {
+        fetcherWrapper: 'testFetchWrapper',
+        umdUrl: 'http://some-url',
+        props: { foo: 'bar' },
+        name: 'pluginName'
+      }
+    ]
+  }
+})
+
+expectError(() => {
+  app.register(mercurius, {
+    schema,
+    resolvers,
+    graphiql: {
+      enabled: true,
+      plugins: [
+        {
+          fetcherWrapper: 'testFetchWrapper',
+          props: { foo: 'bar' }
+        }
+      ]
+    }
+  })
+})

From e27e5b01ae0210cdbc0de259175b1c011d258c80 Mon Sep 17 00:00:00 2001
From: Bartek Igielski <igloczek@gmail.com>
Date: Wed, 2 Nov 2022 15:46:07 +0100
Subject: [PATCH 12/16] Prevent parsing schema exceptions when importing
 directives  (#900)

* Prevent parsing schema extensions

* Add unit test
---
 lib/federation.js  |  2 +-
 test/federation.js | 42 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/lib/federation.js b/lib/federation.js
index 6c1258e4..11d6131f 100644
--- a/lib/federation.js
+++ b/lib/federation.js
@@ -92,7 +92,7 @@ function getStubTypes (schemaDefinitions, isGateway) {
   const directiveDefinitions = []
 
   for (const definition of schemaDefinitions) {
-    if (definition.kind === 'SchemaDefinition') {
+    if (definition.kind === 'SchemaDefinition' || definition.kind === 'SchemaExtension') {
       continue
     }
 
diff --git a/test/federation.js b/test/federation.js
index 2c551039..4c1bcfa4 100644
--- a/test/federation.js
+++ b/test/federation.js
@@ -1087,3 +1087,45 @@ test('basic federation support with \'schema\' in the schema', async (t) => {
     }
   })
 })
+
+test('should support directives import syntax', async (t) => {
+  const app = Fastify()
+
+  const schema = `
+    extend schema
+      @link(url: "https://specs.apollo.dev/federation/v2.0",
+        import: ["@key", "@shareable", "@override"])
+
+    extend type Query {
+      hello: String
+    }
+  `
+
+  const resolvers = {
+    Query: {
+      hello: () => 'world'
+    }
+  }
+
+  app.register(GQL, {
+    schema,
+    resolvers,
+    federationMetadata: true
+  })
+
+  await app.ready()
+
+  const query = '{ _service { sdl } }'
+  const res = await app.inject({
+    method: 'GET',
+    url: `/graphql?query=${query}`
+  })
+
+  t.same(JSON.parse(res.body), {
+    data: {
+      _service: {
+        sdl: schema
+      }
+    }
+  })
+})

From 6933420149b5884084c41322abb71d4bccaf67e8 Mon Sep 17 00:00:00 2001
From: Matteo Collina <hello@matteocollina.com>
Date: Wed, 2 Nov 2022 15:51:54 +0100
Subject: [PATCH 13/16] Bumped v11.3.0

Signed-off-by: Matteo Collina <hello@matteocollina.com>
---
 package.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/package.json b/package.json
index 8c55ee9b..d9068f30 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "mercurius",
-  "version": "11.2.0",
+  "version": "11.3.0",
   "description": "Fastify GraphQL adapter with gateway and subscription support",
   "main": "index.js",
   "types": "index.d.ts",

From d1d8485d738bae4109abcc9ee208bc566693ece7 Mon Sep 17 00:00:00 2001
From: "igor.luckenkov" <igor.luchenkov@amplitude.com>
Date: Wed, 2 Nov 2022 20:13:51 +0000
Subject: [PATCH 14/16] Removed canUseIncrementalExecution check

---
 index.js      |   2 +-
 lib/util.js   |   7 +-
 test/defer.js | 283 +++++++++++++++++++++++++-------------------------
 3 files changed, 143 insertions(+), 149 deletions(-)

diff --git a/index.js b/index.js
index 99b2a19b..ad99787a 100644
--- a/index.js
+++ b/index.js
@@ -562,7 +562,7 @@ const plugin = fp(async function (app, opts) {
       return maybeFormatErrors(execution, context)
     }
 
-    const execution = await executeGraphql({
+    const execution = await executeGraphql(opts.defer, {
       schema: modifiedSchema || fastifyGraphQl.schema,
       document: modifiedDocument || document,
       rootValue: root,
diff --git a/lib/util.js b/lib/util.js
index de348228..b2509f2a 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -26,11 +26,9 @@ function hasExtensionDirective (node) {
   }
 }
 
-const canUseIncrementalExecution = !!require('graphql/execution').experimentalExecuteIncrementally
-
 // istanbul ignore next
-function executeGraphql (args) {
-  if (canUseIncrementalExecution) {
+function executeGraphql (isDeferEnabled, args) {
+  if (isDeferEnabled) {
     return experimentalExecuteIncrementally(args)
   }
 
@@ -45,7 +43,6 @@ const MEDIA_TYPES = {
 module.exports = {
   hasDirective,
   hasExtensionDirective,
-  canUseIncrementalExecution,
   executeGraphql,
   MEDIA_TYPES
 }
diff --git a/test/defer.js b/test/defer.js
index 2d70ef81..f9feb3c3 100644
--- a/test/defer.js
+++ b/test/defer.js
@@ -2,89 +2,116 @@ const { test } = require('tap')
 const Fastify = require('fastify')
 const { fetch } = require('undici')
 const mercurius = require('../index')
-const { canUseIncrementalExecution } = require('../lib/util')
 
-if (canUseIncrementalExecution) {
-  const schema = `
-    type Query {
-      allProducts: [Product!]!
-    }
-    
-    type Product {
-      delivery: DeliveryEstimates!
-      sku: String!
-      id: ID!
+const schema = `
+  type Query {
+    allProducts: [Product!]!
+  }
+  
+  type Product {
+    delivery: DeliveryEstimates!
+    sku: String!
+    id: ID!
+  }
+  
+  type DeliveryEstimates {
+    estimatedDelivery: String!
+    fastestDelivery: String!
+  }`
+
+const allProducts = new Array(1).fill(0).map((_, index) => ({
+  id: `${index}`,
+  sku: 'sku'
+}))
+
+const resolvers = {
+  Query: {
+    allProducts: () => {
+      return allProducts
     }
-    
-    type DeliveryEstimates {
-      estimatedDelivery: String!
-      fastestDelivery: String!
-    }`
-
-  const allProducts = new Array(1).fill(0).map((_, index) => ({
-    id: `${index}`,
-    sku: 'sku'
-  }))
-
-  const resolvers = {
-    Query: {
-      allProducts: () => {
-        return allProducts
-      }
-    },
-    Product: {
-      delivery: () => {
-        return {
-          estimatedDelivery: '25.01.2000',
-          fastestDelivery: '25.01.2000'
-        }
+  },
+  Product: {
+    delivery: () => {
+      return {
+        estimatedDelivery: '25.01.2000',
+        fastestDelivery: '25.01.2000'
       }
     }
   }
+}
 
-  const query = `
-    query deferVariation {
-      allProducts {
-        delivery {
-          ...MyFragment @defer
-        }
-        sku
-        id
+const query = `
+  query deferVariation {
+    allProducts {
+      delivery {
+        ...MyFragment @defer
       }
+      sku
+      id
     }
-  
-    fragment MyFragment on DeliveryEstimates {
-      estimatedDelivery
-      fastestDelivery
-    }
-  `
+  }
+
+  fragment MyFragment on DeliveryEstimates {
+    estimatedDelivery
+    fastestDelivery
+  }
+`
+
+test('errors with @defer when opts.defer is not true', async t => {
+  const app = Fastify()
+  await app.register(mercurius, { schema, resolvers, graphiql: true })
 
-  const wrongAcceptValues = [
-    '',
-    'application/json',
-    'multipart/mixed',
-    'multipart/mixed; deferSpec=12345'
-  ]
+  const res = await app.inject({
+    method: 'POST',
+    url: '/graphql',
+    headers: {
+      'content-type': 'application/json'
+    },
+    body: JSON.stringify({ query })
+  })
 
-  test('errors with @defer when opts.defer is not true', async t => {
+  t.match(res, {
+    statusCode: 400,
+    body: JSON.stringify({
+      data: null,
+      errors: [{
+        message: 'Unknown directive "@defer".', locations: [{ line: 5, column: 23 }]
+      }]
+    })
+  })
+
+  await app.close()
+  t.end()
+})
+
+const wrongAcceptValues = [
+  '',
+  'application/json',
+  'multipart/mixed',
+  'multipart/mixed; deferSpec=12345'
+]
+
+for (const accept of wrongAcceptValues) {
+  test('errors with @defer when used with wrong "accept" header', async t => {
     const app = Fastify()
-    await app.register(mercurius, { schema, resolvers, graphiql: true })
+    await app.register(mercurius, { schema, resolvers, graphiql: true, defer: true })
 
     const res = await app.inject({
       method: 'POST',
       url: '/graphql',
       headers: {
-        'content-type': 'application/json'
+        'content-type': 'application/json',
+        accept
       },
       body: JSON.stringify({ query })
     })
 
     t.match(res, {
-      statusCode: 400,
+      statusCode: 500,
       body: JSON.stringify({
         data: null,
         errors: [{
-          message: 'Unknown directive "@defer".', locations: [{ line: 5, column: 25 }]
+          message: 'Server received an operation that uses incremental delivery (@defer or @stream), but the client does not accept multipart/mixed HTTP responses. To enable incremental delivery support, add the HTTP header "Accept: multipart/mixed; deferSpec=20220824".'
         }]
       })
     })
@@ -92,64 +119,35 @@ if (canUseIncrementalExecution) {
     await app.close()
     t.end()
   })
+}
 
-  for (const accept of wrongAcceptValues) {
-    test('errors with @defer when used with wrong "accept" header', async t => {
-      const app = Fastify()
-      await app.register(mercurius, { schema, resolvers, graphiql: true, defer: true })
-
-      const res = await app.inject({
-        method: 'POST',
-        url: '/graphql',
-        headers: {
-          'content-type': 'application/json',
-          accept
-        },
-        body: JSON.stringify({ query })
-      })
+const correctAcceptValues = [
+  'multipart/mixed; deferSpec=20220824',
+  'multipart/mixed; deferSpec=20220824, application/json',
+  'application/json, multipart/mixed; deferSpec=20220824'
+]
 
-      t.match(res, {
-        statusCode: 500,
-        body: JSON.stringify({
-          data: null,
-          errors: [{
-            message: 'Server received an operation that uses incremental delivery (@defer or @stream), but the client does not accept multipart/mixed HTTP responses. To enable incremental delivery support, add the HTTP header "Accept: multipart/mixed; deferSpec=20220824".'
-          }]
-        })
-      })
+for (const accept of correctAcceptValues) {
+  test('works with @defer when used with correct "accept" header', async t => {
+    const app = Fastify()
+    await app.register(mercurius, { schema, resolvers, graphiql: true, defer: true })
 
-      await app.close()
-      t.end()
+    const res = await app.inject({
+      method: 'POST',
+      url: '/graphql',
+      headers: {
+        'content-type': 'application/json',
+        accept
+      },
+      body: JSON.stringify({ query })
     })
-  }
 
-  const correctAcceptValues = [
-    'multipart/mixed; deferSpec=20220824',
-    'multipart/mixed; deferSpec=20220824, application/json',
-    'application/json, multipart/mixed; deferSpec=20220824'
-  ]
-
-  for (const accept of correctAcceptValues) {
-    test('works with @defer when used with correct "accept" header', async t => {
-      const app = Fastify()
-      await app.register(mercurius, { schema, resolvers, graphiql: true, defer: true })
-
-      const res = await app.inject({
-        method: 'POST',
-        url: '/graphql',
-        headers: {
-          'content-type': 'application/json',
-          accept
-        },
-        body: JSON.stringify({ query })
-      })
-
-      t.match(res, {
-        statusCode: 200,
-        headers: {
-          'content-type': 'multipart/mixed; boundary="-"; deferSpec=20220824'
-        },
-        body: `\r
+    t.match(res, {
+      statusCode: 200,
+      headers: {
+        'content-type': 'multipart/mixed; boundary="-"; deferSpec=20220824'
+      },
+      body: `\r
 ---\r
 content-type: application/json; charset=utf-8\r
 \r
@@ -160,32 +158,32 @@ content-type: application/json; charset=utf-8\r
 {"hasNext":false,"incremental":[{"path":["allProducts",0,"delivery"],"data":{"estimatedDelivery":"25.01.2000","fastestDelivery":"25.01.2000"}}]}\r
 -----\r
 `
-      })
-
-      await app.close()
-      t.end()
     })
-  }
 
-  test('returns stream when using undici.fetch with @defer', async t => {
-    const app = Fastify()
-    await app.register(mercurius, { schema, resolvers, graphiql: true, defer: true })
-    const url = await app.listen({ port: 0 })
+    await app.close()
+    t.end()
+  })
+}
 
-    const res = await fetch(`${url}/graphql`, {
-      method: 'POST',
-      headers: {
-        'content-type': 'application/json',
-        accept: 'multipart/mixed; deferSpec=20220824'
-      },
-      body: JSON.stringify({ query })
-    })
+test('returns stream when using undici.fetch with @defer', async t => {
+  const app = Fastify()
+  await app.register(mercurius, { schema, resolvers, graphiql: true, defer: true })
+  const url = await app.listen({ port: 0 })
 
-    const reader = res.body.getReader()
-    const { value } = await reader.read()
-    const result = new TextDecoder('utf-8').decode(value)
+  const res = await fetch(`${url}/graphql`, {
+    method: 'POST',
+    headers: {
+      'content-type': 'application/json',
+      accept: 'multipart/mixed; deferSpec=20220824'
+    },
+    body: JSON.stringify({ query })
+  })
 
-    t.same(result, `\r
+  const reader = res.body.getReader()
+  const { value } = await reader.read()
+  const result = new TextDecoder('utf-8').decode(value)
+
+  t.same(result, `\r
 ---\r
 content-type: application/json; charset=utf-8\r
 \r
@@ -197,15 +195,14 @@ content-type: application/json; charset=utf-8\r
 -----\r
 `)
 
-    t.same(res.status, 200)
-    t.same(res.headers.get('content-type'), 'multipart/mixed; boundary="-"; deferSpec=20220824')
-
-    t.teardown(async () => {
-      await reader.releaseLock()
-      app.close()
-      process.exit()
-    })
+  t.same(res.status, 200)
+  t.same(res.headers.get('content-type'), 'multipart/mixed; boundary="-"; deferSpec=20220824')
 
-    t.end()
+  t.teardown(async () => {
+    await reader.releaseLock()
+    app.close()
+    process.exit()
   })
-}
+
+  t.end()
+})

From 640300f3dae06f3652af34d9aa6d36410a241bd7 Mon Sep 17 00:00:00 2001
From: "igor.luckenkov" <igor.luchenkov@amplitude.com>
Date: Wed, 2 Nov 2022 20:40:19 +0000
Subject: [PATCH 15/16] Throw an error if JIT is used together with defer,
 update the docs

---
 docs/api/options.md |  3 +++
 index.js            |  4 ++++
 test/defer.js       | 14 ++++++++++++++
 3 files changed, 21 insertions(+)

diff --git a/docs/api/options.md b/docs/api/options.md
index cf57686e..1512f8f8 100644
--- a/docs/api/options.md
+++ b/docs/api/options.md
@@ -53,6 +53,9 @@
 - `jit`: Integer. The minimum number of execution a query needs to be
   executed before being jit'ed.
   - Default: `0`, jit is disabled.
+  - _jit can't be used together with `defer: true`_
+- `defer`: boolean. Default: `false`. Enable @defer directive execution.
+  - _defer can't be used together with `jit`_
 - `routes`: boolean. Serves the Default: `true`. A graphql endpoint is
   exposed at `/graphql`.
 - `path`: string. Change default graphql `/graphql` route to another one.
diff --git a/index.js b/index.js
index ad99787a..2e547690 100644
--- a/index.js
+++ b/index.js
@@ -190,6 +190,10 @@ const plugin = fp(async function (app, opts) {
   }
 
   if (opts.defer) {
+    if (opts.jit) {
+      throw new MER_ERR_INVALID_OPTS("@defer and JIT can't be used together")
+    }
+
     app.register(require('@fastify/accepts'))
 
     schema = extendSchema(
diff --git a/test/defer.js b/test/defer.js
index f9feb3c3..3b3f559a 100644
--- a/test/defer.js
+++ b/test/defer.js
@@ -84,6 +84,20 @@ test('errors with @defer when opts.defer is not true', async t => {
   t.end()
 })
 
+test('errors when used with both JIT and @defer', async t => {
+  const app = Fastify()
+
+  try {
+    await app.register(mercurius, { jit: 1, defer: true })
+    t.fail('Should not successfully start the server')
+  } catch (ex) {
+    t.equal(ex.message, "Invalid options: @defer and JIT can't be used together")
+  }
+
+  await app.close()
+  t.end()
+})
+
 const wrongAcceptValues = [
   '',
   'application/json',

From 8b7e9b24d456861d9d0db133b5463637f064f973 Mon Sep 17 00:00:00 2001
From: "igor.luckenkov" <igor.luchenkov@amplitude.com>
Date: Wed, 2 Nov 2022 20:40:19 +0000
Subject: [PATCH 16/16] Throw an error if JIT is used together with defer,
 update the docs

---
 docs/api/options.md |  3 +++
 index.d.ts          |  7 +++++++
 index.js            |  4 ++++
 test/defer.js       | 14 ++++++++++++++
 4 files changed, 28 insertions(+)

diff --git a/docs/api/options.md b/docs/api/options.md
index cf57686e..2743aa7d 100644
--- a/docs/api/options.md
+++ b/docs/api/options.md
@@ -53,6 +53,9 @@
 - `jit`: Integer. The minimum number of execution a query needs to be
   executed before being jit'ed.
   - Default: `0`, jit is disabled.
+  - _jit can't be used together with `defer: true`_
+- `defer`: boolean. Default: `false`. Enable @defer directive execution support.
+  - _defer can't be used together with `jit`_
 - `routes`: boolean. Serves the Default: `true`. A graphql endpoint is
   exposed at `/graphql`.
 - `path`: string. Change default graphql `/graphql` route to another one.
diff --git a/index.d.ts b/index.d.ts
index 5673216c..1d84a466 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -473,9 +473,16 @@ export interface MercuriusCommonOptions {
   ide?: boolean | 'graphiql' | MercuriusGraphiQLOptions;
   /**
    * The minimum number of execution a query needs to be executed before being jit'ed.
+   * Can't be enabled with MercuriusCommonOptions.defer
    * @default 0 - disabled
    */
   jit?: number;
+  /**
+   * Enable @defer directive execution support.
+   * Can't be enabled with MercuriusCommonOptions.jit
+   * @default false
+   */
+  defer?: boolean;
   /**
    * A graphql endpoint is exposed at /graphql when true
    * @default true
diff --git a/index.js b/index.js
index ad99787a..2e547690 100644
--- a/index.js
+++ b/index.js
@@ -190,6 +190,10 @@ const plugin = fp(async function (app, opts) {
   }
 
   if (opts.defer) {
+    if (opts.jit) {
+      throw new MER_ERR_INVALID_OPTS("@defer and JIT can't be used together")
+    }
+
     app.register(require('@fastify/accepts'))
 
     schema = extendSchema(
diff --git a/test/defer.js b/test/defer.js
index f9feb3c3..3b3f559a 100644
--- a/test/defer.js
+++ b/test/defer.js
@@ -84,6 +84,20 @@ test('errors with @defer when opts.defer is not true', async t => {
   t.end()
 })
 
+test('errors when used with both JIT and @defer', async t => {
+  const app = Fastify()
+
+  try {
+    await app.register(mercurius, { jit: 1, defer: true })
+    t.fail('Should not successfully start the server')
+  } catch (ex) {
+    t.equal(ex.message, "Invalid options: @defer and JIT can't be used together")
+  }
+
+  await app.close()
+  t.end()
+})
+
 const wrongAcceptValues = [
   '',
   'application/json',