add rest collection tests for relationships

src/collections/requestHandlers/collections.spec.js

@@ -547,4 +547,76 @@ describe('Collections - REST', () => {
       });
     });
   });
+
+  describe('Relationships', () => {
+    let documentA;
+    let documentB;
+
+    beforeAll(async (done) => {
+      // create document a
+      const createA = await fetch(`${url}/api/relationship-a`, {
+        body: JSON.stringify({}),
+        headers: {
+          Authorization: `JWT ${token}`,
+          'Content-Type': 'application/json',
+        },
+        method: 'post',
+      });
+      const createAData = await createA.json();
+      // create document b, related to a
+      const createB = await fetch(`${url}/api/relationship-b`, {
+        body: JSON.stringify({
+          post: [createAData.doc.id],
+        }),
+        headers: {
+          Authorization: `JWT ${token}`,
+          'Content-Type': 'application/json',
+        },
+        method: 'post',
+      });
+      // update a to relate to b
+      const createBData = await createB.json();
+      documentB = createBData.doc;
+      const updateA = await fetch(`${url}/api/relationship-a/${createAData.doc.id}`, {
+        body: JSON.stringify({
+          post: documentB.id,
+        }),
+        headers: {
+          Authorization: `JWT ${token}`,
+          'Content-Type': 'application/json',
+        },
+        method: 'put',
+      });
+      const updateAData = await updateA.json();
+      documentA = updateAData.doc;
+      done();
+    });
+
+    it('should create and read collections with relationships', async () => {
+      expect(documentA.post).not.toBeNull();
+      expect(documentB.post).toHaveLength(1);
+    });
+
+    it('should use depth to limit the number of relationships returned', async () => {
+      const response = await fetch(`${url}/api/relationship-a?depth=3`, {
+        headers: {
+          Authorization: `JWT ${token}`,
+          'Content-Type': 'application/json',
+        },
+        method: 'get',
+      });
+      const data = await response.json();
+      const [doc] = data.docs;
+      expect(doc.id).toBe(documentA.id);
+      let nested = doc.post;
+      expect(nested.id).toBe(documentB.id);
+      [nested] = nested.post;
+      expect(nested.id).toBe(documentA.id);
+      nested = nested.post;
+      expect(nested.id).toBe(documentB.id);
+      [nested] = nested.post;
+      expect(nested).not.toHaveProperty('post');
+      expect(nested).toBe(documentA.id);
+    });
+  });
 });