Create notifications on UpdatePost, too

Note that we don't create duplicate notifications. I made use of the behaviour
of XSS-middleware: It removes all css classes from `<a>` anchors. Because
notifications rely on a css class `mention` which gets removed in a later
middleware, this gives us a nice behaviour for re-notifications without creating
duplicates. The downside is that it creates dependencies between middlewares and
it's not that obvious at all.

cc @mattwr18 @ulfgebhardt @appinteractive @Tirokk

backend/src/middleware/notifications/index.js

@@ -1,11 +1,13 @@
 import extractIds from './extractMentions'
 
 const notify = async (resolve, root, args, context, resolveInfo) => {
-  const ids = extractIds(args.content) // before mention class gets removed
+  // extract user ids before xss-middleware removes link classes
+  const ids = extractIds(args.content)
+
   const post = await resolve(root, args, context, resolveInfo)
 
   const session = context.driver.session()
-  const { content, id: postId } = post
+  const { id: postId } = post
   const createdAt = (new Date()).toISOString()
   const cypher = `
     match(u:User) where u.id in $ids
@@ -22,6 +24,7 @@ const notify = async (resolve, root, args, context, resolveInfo) => {
 
 export default {
   Mutation: {
-    CreatePost: notify
+    CreatePost: notify,
+    UpdatePost: notify
   }
 }

backend/src/middleware/notifications/spec.js

@@ -74,16 +74,50 @@ describe('currentUser { notifications }', () => {
         })
 
         it('sends you a notification', async () => {
-          const newContent = 'Hey <a href="/profile/you/al-capone" target=\"_blank\">@al-capone</a> how do you do?'
+          const expectedContent = 'Hey <a href="/profile/you/al-capone" target="_blank">@al-capone</a> how do you do?'
           const expected = {
             currentUser: {
               notifications: [
-                { read: false, post: { content: newContent } }
+                { read: false, post: { content: expectedContent } }
               ]
             }
           }
           await expect(client.request(query, { read: false })).resolves.toEqual(expected)
         })
+
+        describe('who mentions me again', () => {
+          beforeEach(async () => {
+            const updatedContent = `${post.content} One more mention to <a href="/profile/you" class="mention">@al-capone</a>`
+            // The response `post.content` contains a link but the XSSmiddleware
+            // should have the `mention` CSS class removed. I discovered this
+            // during development and thought: A feature not a bug! This way we
+            // can encode a re-mentioning of users when you edit your post or
+            // comment.
+            const createPostMutation = `
+            mutation($id: ID!, $content: String!) {
+              UpdatePost(id: $id, content: $content) {
+                title
+                content
+              }
+            }
+            `
+            authorClient = new GraphQLClient(host, { headers: authorHeaders })
+            await authorClient.request(createPostMutation, { id: post.id, content: updatedContent })
+          })
+
+          it('creates exactly one more notification', async () => {
+            const expectedContent = 'Hey <a href="/profile/you/al-capone" target="_blank">@al-capone</a> how do you do? One more mention to <a href="/profile/you" target="_blank">@al-capone</a>'
+            const expected = {
+              currentUser: {
+                notifications: [
+                  { read: false, post: { content: expectedContent } },
+                  { read: false, post: { content: expectedContent } }
+                ]
+              }
+            }
+            await expect(client.request(query, { read: false })).resolves.toEqual(expected)
+          })
+        })
       })
     })
   })