Expose cannot read property id of null error

CC @appinteractive

src/middleware/slugifyMiddleware.spec.js

@@ -0,0 +1,65 @@
+import { create, cleanDatabase } from '../seed/factories'
+import { testServerHost as host, authenticatedHeaders } from '../jest/helpers'
+import { GraphQLClient } from 'graphql-request'
+
+let client
+let headers
+beforeEach(async () => {
+  await create('user', {email: 'user@example.org', password: '1234'})
+  headers = authenticatedHeaders({email: 'user@example.org', password: '1234'})
+  client = new GraphQLClient(host, { headers })
+})
+
+afterEach(async () => {
+  await cleanDatabase()
+})
+
+describe('slugify', () => {
+  describe('CreatePost', () => {
+    it('generates a slug based on the title', async () => {
+      const response = await client.request(`mutation {
+        CreatePost(
+          title: "I am a brand new post",
+          content: "Some content"
+        ) { slug }
+      }`)
+      expect(response).toEqual({ CreatePost: { slug: 'i-am-a-brand-new-post' } })
+    })
+
+    describe('if slug exists', () => {
+      beforeEach(async () => {
+        await create('post', {
+          title: 'Pre-existing post',
+          slug: 'pre-existing-post'
+        }, { headers })
+      })
+
+      it('chooses another slug', async () => {
+        const response = await client.request(`mutation {
+          CreatePost(
+            title: "Pre-existing post",
+            content: "Some content"
+          ) { slug }
+        }`)
+        expect(response).toEqual({ CreatePost: { slug: 'pre-existing-post-1' } })
+      })
+
+      describe('but if the client requested a slug', () => {
+        it('rejects CreatePost', async () => {
+          try {
+            await client.request(`mutation {
+              CreatePost(
+                title: "Pre-existing post",
+                content: "Some content",
+                slug: "pre-existing-post"
+              ) { slug }
+            }`)
+          } catch (error) {
+            expect(error.response.errors[0].message).toEqual('Not Authorised!')
+            expect(error.response.data).toEqual({ User: [ { email: null } ] })
+          }
+        })
+      })
+    })
+  })
+})