fix: cope with null relationships (#909)

Refs #859

Author: char0n

src/index.js

@@ -12,8 +12,16 @@ import {
   insert,
   assocPath,
   pickBy,
+  both,
+  propSatisfies,
 } from 'ramda';
-import { mapIndexed, reduceIndexed, ensureArray, isArray } from 'ramda-adjunct';
+import {
+  mapIndexed,
+  reduceIndexed,
+  ensureArray,
+  isArray,
+  isNotNull,
+} from 'ramda-adjunct';
 
 // Type definitions:
 //     Resource = Object
@@ -27,7 +35,7 @@ import { mapIndexed, reduceIndexed, ensureArray, isArray } from 'ramda-adjunct';
 // getRelationships :: Resource -> Relationships
 const getRelationships = pipe(
   propOr({}, ['relationships']),
-  pickBy(has('data')),
+  pickBy(both(has('data'), propSatisfies(isNotNull, 'data'))),
   keys
 );
 

test/index.js

@@ -787,6 +787,48 @@ describe('jsonApiMerge', function () {
     });
   });
 
+  context(
+    'given relationships have data property containing null',
+    function () {
+      const jsonApiData = {
+        data: {
+          id: 1,
+          type: 'resource',
+          attributes: {
+            name: 'Resource name',
+          },
+          relationships: {
+            related: {
+              links: {
+                related: {
+                  href: 'http://example.com/related-resource/',
+                  title: 'Related',
+                },
+              },
+              data: null,
+            },
+          },
+        },
+        included: [
+          {
+            id: 2,
+            type: 'related_resource',
+            attributes: {
+              name: 'Related resource name',
+            },
+          },
+        ],
+      };
+
+      specify('should do nothing', function () {
+        const actual = jsonApiMerge(jsonApiData.included, jsonApiData.data);
+        const expected = actual;
+
+        assert.deepEqual(actual, expected);
+      });
+    }
+  );
+
   it('should curry', function () {
     const jsonApiData = {
       data: {