fix(kitsu-core): prevent relationship mutation during multi-circular deserialisation (#722)

* test(kitsu-core): add test for multi-circular deserialisation

specifically if Article1 and Article2 are deserialized in primary data, but also
references directly by a relationship of Article1, such as Author1

This makes Article1 deserialize first, then its relationship Author1 is
deserialised, along with its relationships Article1 and Article 2

Once the entire chain is complete in Article1, Article2 is deserialised
in the main data, but due to being mutated by the prior deserialisation,
it has no items in its relationships key

* fix(kitsu-core): fix cyclic deserialisation of primary data

use object assigns to ensure `delete` calls do not modify objects in
future iterations of the deserialiseArray loop

Author: pedep

packages/kitsu-core/src/deserialise/index.js

@@ -12,7 +12,11 @@ function deserialiseArray (array) {
   const previouslyLinked = {}
   const relationshipCache = {}
   for (let value of array.data) {
-    value = linkRelationships(value, [ ...array.data, ...(array.included || []) ], previouslyLinked, relationshipCache)
+    const included = [
+      ...array.data.map(item => ({ ...item, relationships: { ...item.relationships } })),
+      ...(array.included || [])
+    ]
+    value = linkRelationships(value, included, previouslyLinked, relationshipCache)
     if (value.attributes) value = deattribute(value)
     array.data[array.data.indexOf(value)] = value
   }

packages/kitsu-core/src/deserialise/index.spec.js

@@ -1102,4 +1102,149 @@ describe('kitsu-core', () => {
       expect(input).toEqual(output)
     })
   })
+
+  it('Deserializes first level resources after being serialized as a relationship', () => {
+    expect.assertions(1)
+
+    const input = JSON.parse(stringify(deserialise({
+      data: [
+        {
+          id: '5',
+          type: 'articles',
+          attributes: { title: 'asd0' },
+          relationships: {
+            author: {
+              data: {
+                id: '11',
+                type: 'authors'
+              },
+              links: { self: 'http://kitsu.example.com/authors' },
+              meta: { authors: 'articles#5' }
+            }
+          }
+        },
+        {
+          id: '6',
+          type: 'articles',
+          attributes: { title: 'asd1' },
+          relationships: {
+            author: {
+              data: {
+                id: '11',
+                type: 'authors'
+              },
+              links: { self: 'http://kitsu.example.com/authors' },
+              meta: { authors: 'articles#6' }
+            }
+          }
+        }
+      ],
+      included: [
+        {
+          id: '11',
+          type: 'authors',
+          attributes: { first_name: 'Egon', last_name: 'Egonsen' },
+          relationships: {
+            articles: {
+              data: [
+                {
+                  id: '5',
+                  type: 'articles'
+                },
+                {
+                  id: '6',
+                  type: 'articles'
+                }
+              ]
+            }
+          }
+        }
+      ]
+    })))
+
+    const output = {
+      data: [
+        {
+          id: '5',
+          type: 'articles',
+          title: 'asd0',
+          author: {
+            links: { self: 'http://kitsu.example.com/authors' },
+            meta: { authors: 'articles#5' },
+            data: {
+              id: '11',
+              type: 'authors',
+              first_name: 'Egon',
+              last_name: 'Egonsen',
+              articles: {
+                data: [
+                  {
+                    id: '5',
+                    type: 'articles',
+                    title: 'asd0',
+                    author: {
+                      data: '[Circular ~.data.0.author.data]',
+                      links: { self: 'http://kitsu.example.com/authors' },
+                      meta: { authors: 'articles#5' }
+                    }
+                  },
+                  {
+                    id: '6',
+                    type: 'articles',
+                    title: 'asd1',
+                    author: {
+                      data: '[Circular ~.data.0.author.data]',
+                      links: { self: 'http://kitsu.example.com/authors' },
+                      meta: { authors: 'articles#6' }
+                    }
+                  }
+                ]
+              }
+            }
+          }
+        },
+        {
+          id: '6',
+          type: 'articles',
+          title: 'asd1',
+          author: {
+            links: { self: 'http://kitsu.example.com/authors' },
+            meta: { authors: 'articles#6' },
+            data: {
+              id: '11',
+              type: 'authors',
+              first_name: 'Egon',
+              last_name: 'Egonsen',
+              articles: {
+                data: [
+                  {
+                    id: '5',
+                    type: 'articles',
+                    title: 'asd0',
+                    author: {
+                      data: '[Circular ~.data.1.author.data]',
+                      links: { self: 'http://kitsu.example.com/authors' },
+                      meta: { authors: 'articles#5' }
+                    }
+                  },
+                  {
+                    id: '6',
+                    type: 'articles',
+                    title: 'asd1',
+                    author: {
+                      data: '[Circular ~.data.1.author.data]',
+                      links: { self: 'http://kitsu.example.com/authors' },
+                      meta: { authors: 'articles#6' }
+                    }
+                  }
+                ]
+              }
+            }
+          }
+        }
+      ]
+    }
+
+    expect(input).toEqual(output)
+  })
 })