fix: apply updated schema on refresh

lib/gateway/build-gateway.js

@@ -614,6 +614,9 @@ async function buildGateway (serviceMap, gatewayOpts, app, lruGatewayResolvers)
 
       defineResolvers(schema, typeToServiceMap, serviceMap, typeFieldsToService, factory, lruGatewayResolvers)
 
+      this.schema = schema
+      app.graphql.replaceSchema(this.schema)
+
       return schema
     },
     close

test/pollingInterval.js

@@ -455,7 +455,7 @@ test("Polling schemas (if service is down, schema shouldn't be changed)", async
     })
   }
 
-  await userService.close()
+  userService.close()
   await t.context.clock.tickAsync(500)
 
   {

test/schemaRefresh.js

@@ -0,0 +1,152 @@
+'use strict'
+
+const { test } = require('tap')
+
+const Fastify = require('fastify')
+const { buildFederationSchema } = require('@mercuriusjs/federation')
+const GQL = require('mercurius')
+const plugin = require('../index')
+
+test('Refreshing gateway schema', async (t) => {
+  const resolvers = {
+    Query: {
+      me: () => user
+    },
+    User: {
+      __resolveReference: (user) => user
+    }
+  }
+
+  const user = {
+    id: 'u1',
+    name: 'John',
+    lastName: 'Doe'
+  }
+
+  const userService = Fastify()
+  const gateway = Fastify()
+  t.teardown(async () => {
+    await gateway.close()
+    await userService.close()
+  })
+
+  userService.register(GQL, {
+    schema: buildFederationSchema(`
+      extend type Query {
+        me: User
+      }
+
+      type User @key(fields: "id") {
+        id: ID!
+        name: String!
+      }
+    `),
+    resolvers
+  })
+
+  await userService.listen({ port: 0 })
+
+  const userServicePort = userService.server.address().port
+
+  await gateway.register(plugin, {
+    gateway: {
+      services: [
+        {
+          name: 'user',
+          url: `http://localhost:${userServicePort}/graphql`
+        }
+      ],
+      cache: false
+    }
+  })
+
+  const res = await gateway.inject({
+    method: 'POST',
+    headers: {
+      'content-type': 'application/json'
+    },
+    url: '/graphql',
+    body: JSON.stringify({
+      query: `
+        query introspect {
+          __type(name: "User") {
+            fields {
+              name
+            }
+          }
+        }
+      `
+    })
+  })
+
+  t.same(res.json(), {
+    data: {
+      __type: {
+        fields: [
+          {
+            name: 'id'
+          },
+          {
+            name: 'name'
+          }
+        ]
+      }
+    }
+  })
+
+  // Update User service schema
+
+  userService.graphql.replaceSchema(
+    buildFederationSchema(`
+      extend type Query {
+        me: User
+      }
+
+      type User @key(fields: "id") {
+        id: ID!
+        name: String!
+        lastName: String!
+      }
+    `)
+  )
+  userService.graphql.defineResolvers(resolvers)
+
+  await gateway.graphqlGateway.refresh()
+
+  const updatedRes = await gateway.inject({
+    method: 'POST',
+    headers: {
+      'content-type': 'application/json'
+    },
+    url: '/graphql',
+    body: JSON.stringify({
+      query: `
+        query introspect {
+          __type(name: "User") {
+            fields {
+              name
+            }
+          }
+        }
+      `
+    })
+  })
+
+  t.same(updatedRes.json(), {
+    data: {
+      __type: {
+        fields: [
+          {
+            name: 'id'
+          },
+          {
+            name: 'name'
+          },
+          {
+            name: 'lastName'
+          }
+        ]
+      }
+    }
+  })
+})