diff --git a/jest.config.js b/jest.config.js
index 863003b..cec63b6 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -1,13 +1,12 @@
 module.exports = {
-    preset: 'ts-jest',
-    setupTestFrameworkScriptFile: './jest.setup.js',
-    testEnvironment: 'node',
     clearMocks : true,
     moduleFileExtensions: [
         "ts",
         "js",
     ],
+    preset: 'ts-jest',
+    testEnvironment: 'node',
     testMatch: [
         "**/*.test.ts"
     ],
-};
\ No newline at end of file
+};
diff --git a/package-lock.json b/package-lock.json
index d2582e1..46b2ce6 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -5090,7 +5090,8 @@
         "ansi-regex": {
           "version": "2.1.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "aproba": {
           "version": "1.2.0",
@@ -5111,12 +5112,14 @@
         "balanced-match": {
           "version": "1.0.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "brace-expansion": {
           "version": "1.1.11",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "balanced-match": "^1.0.0",
             "concat-map": "0.0.1"
@@ -5131,17 +5134,20 @@
         "code-point-at": {
           "version": "1.1.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "concat-map": {
           "version": "0.0.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "console-control-strings": {
           "version": "1.1.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "core-util-is": {
           "version": "1.0.2",
@@ -5258,7 +5264,8 @@
         "inherits": {
           "version": "2.0.3",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "ini": {
           "version": "1.3.5",
@@ -5270,6 +5277,7 @@
           "version": "1.0.0",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "number-is-nan": "^1.0.0"
           }
@@ -5284,6 +5292,7 @@
           "version": "3.0.4",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "brace-expansion": "^1.1.7"
           }
@@ -5291,12 +5300,14 @@
         "minimist": {
           "version": "0.0.8",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "minipass": {
           "version": "2.3.5",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "safe-buffer": "^5.1.2",
             "yallist": "^3.0.0"
@@ -5315,6 +5326,7 @@
           "version": "0.5.1",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "minimist": "0.0.8"
           }
@@ -5395,7 +5407,8 @@
         "number-is-nan": {
           "version": "1.0.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "object-assign": {
           "version": "4.1.1",
@@ -5407,6 +5420,7 @@
           "version": "1.4.0",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "wrappy": "1"
           }
@@ -5492,7 +5506,8 @@
         "safe-buffer": {
           "version": "5.1.2",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "safer-buffer": {
           "version": "2.1.2",
@@ -5528,6 +5543,7 @@
           "version": "1.0.2",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "code-point-at": "^1.0.0",
             "is-fullwidth-code-point": "^1.0.0",
@@ -5547,6 +5563,7 @@
           "version": "3.0.1",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "ansi-regex": "^2.0.0"
           }
@@ -5590,12 +5607,14 @@
         "wrappy": {
           "version": "1.0.2",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "yallist": {
           "version": "3.0.3",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         }
       }
     },
diff --git a/src/schema/common/common-entity-interface.ts b/src/schema/common/common-entity-interface.ts
index af82292..c0ac6b2 100644
--- a/src/schema/common/common-entity-interface.ts
+++ b/src/schema/common/common-entity-interface.ts
@@ -2,5 +2,6 @@ export const CommonEntityInterface = `interface CommonEntity {
                                           id: ID!
                                           creationDate: Date,
                                           lastUpdateDate: Date,
-                                          dataVersion: Int!
+                                          dataVersion: Int!,
+                                          realityId: Int!
                                       }`;
diff --git a/test/integration-tests/test-server/client.ts b/test/integration-tests/test-server/client.ts
index 393149f..9230aed 100644
--- a/test/integration-tests/test-server/client.ts
+++ b/test/integration-tests/test-server/client.ts
@@ -5,7 +5,7 @@ export const url = `http://localhost:${polarisPropertiesPath.port}${
     polarisPropertiesPath.endpoint
 }`;
 
-export const graphqlRequest = async (data: string, headers: any, variables: any) => {
+export const graphQLRequest = async (data: string, headers: any, variables: any = undefined) => {
     const graphQLClient = new GraphQLClient(url, { headers });
     return graphQLClient.request(data, variables);
 };
diff --git a/test/integration-tests/test-server/dal/author-model.ts b/test/integration-tests/test-server/dal/author-model.ts
new file mode 100644
index 0000000..01bd7fd
--- /dev/null
+++ b/test/integration-tests/test-server/dal/author-model.ts
@@ -0,0 +1,16 @@
+import { getModelCreator, RepositoryModel } from '@enigmatis/mongo-driver';
+import { Schema } from 'mongoose';
+
+export interface Author extends RepositoryModel {
+    testId: string;
+    firstName: string;
+    lastName: string;
+}
+
+export const authorSchema: Schema = new Schema({
+    testId: String,
+    firstName: String,
+    lastName: String,
+});
+
+export const AuthorModelPerReality = getModelCreator<Author>('author', authorSchema);
diff --git a/test/integration-tests/test-server/dal/book-model.ts b/test/integration-tests/test-server/dal/book-model.ts
index 46fc73d..1d565db 100644
--- a/test/integration-tests/test-server/dal/book-model.ts
+++ b/test/integration-tests/test-server/dal/book-model.ts
@@ -1,20 +1,24 @@
-import { getModelCreator, RepositoryModel } from '@enigmatis/mongo-driver';
+import { getModelCreator, RepositoryModel, SchemaCreator } from '@enigmatis/mongo-driver';
 import { Schema } from 'mongoose';
+import { Author } from './author-model';
 
 export interface Book extends RepositoryModel {
     testId: string;
     title: string;
-    author: string;
-    otherBook: Book;
+    author: Author;
     dataVersion: number;
 }
 
-export const bookSchema: Schema = new Schema({
-    testId: String,
-    title: String,
-    author: String,
-    otherBook: Object,
-    dataVersion: Number,
-});
+export const bookSchema: SchemaCreator = refNameCreator => {
+    return new Schema({
+        testId: String,
+        title: String,
+        author: {
+            type: Schema.Types.ObjectId,
+            ref: refNameCreator('author'),
+        },
+        dataVersion: Number,
+    });
+};
 
 export const BookModelPerReality = getModelCreator<Book>('book', bookSchema);
diff --git a/test/integration-tests/test-server/run-test.ts b/test/integration-tests/test-server/run-test.ts
index 311a7af..5c6c33d 100644
--- a/test/integration-tests/test-server/run-test.ts
+++ b/test/integration-tests/test-server/run-test.ts
@@ -2,7 +2,8 @@ import { closeConnection, initConnection } from '@enigmatis/mongo-driver';
 import { config } from 'dotenv';
 import * as mongoose from 'mongoose';
 import { logger, server } from './server';
-export async function init() {
+
+export async function startTestServer() {
     config();
     jest.setTimeout(15000);
     const connectionString =
@@ -12,7 +13,7 @@ export async function init() {
     server.start();
 }
 
-export async function finish() {
+export async function stopTestServer() {
     await closeConnection();
     await server.stop();
 }
diff --git a/test/integration-tests/test-server/schema/definitions/author.ts b/test/integration-tests/test-server/schema/definitions/author.ts
new file mode 100644
index 0000000..98bc684
--- /dev/null
+++ b/test/integration-tests/test-server/schema/definitions/author.ts
@@ -0,0 +1,8 @@
+import { RepositoryEntity } from '../../../../../src/main';
+
+export interface Author extends RepositoryEntity {
+    testId: string;
+    id: string;
+    firstName: string;
+    lastName: string;
+}
diff --git a/test/integration-tests/test-server/schema/definitions/book.ts b/test/integration-tests/test-server/schema/definitions/book.ts
index 87a9a19..8b67420 100644
--- a/test/integration-tests/test-server/schema/definitions/book.ts
+++ b/test/integration-tests/test-server/schema/definitions/book.ts
@@ -1,9 +1,9 @@
 import { RepositoryEntity } from '../../../../../src/main';
+import { Author } from './author';
 
 export interface Book extends RepositoryEntity {
     testId: string;
     id: string;
     title: string;
-    author: string;
-    otherBook?: Book;
+    author: Author;
 }
diff --git a/test/integration-tests/test-server/schema/resolvers/book-resolvers-functions.ts b/test/integration-tests/test-server/schema/resolvers/book-resolvers-functions.ts
index 6cf151a..93e2c41 100644
--- a/test/integration-tests/test-server/schema/resolvers/book-resolvers-functions.ts
+++ b/test/integration-tests/test-server/schema/resolvers/book-resolvers-functions.ts
@@ -1,6 +1,8 @@
 import { QueryWithIrrelevant } from '@enigmatis/mongo-driver';
+import { PolarisRequestHeaders } from '@enigmatis/utills';
 import { UserInputError } from 'apollo-server-koa';
 import { PolarisContext } from '../../../../../src/server/polaris-context';
+import { AuthorModelPerReality } from '../../dal/author-model';
 import { BookModelPerReality } from '../../dal/book-model';
 import { Book } from '../definitions/book';
 import { BOOK_UPDATED } from './subscription-event-names';
@@ -34,9 +36,18 @@ export const bookResolver = async (
     query: object,
     context: PolarisContext,
 ) => {
-    const { realityId } = context.headers;
+    const { realityId, includeLinkedOperation } = context.headers;
     if (!Number.isInteger(realityId as any)) {
         throw new UserInputError('please provide reality-id header');
+    } else if (includeLinkedOperation) {
+        const zeroRealityHeaders = { ...context.headers };
+        zeroRealityHeaders.realityId = 0;
+        const zeroRealityContext = { ...context };
+        zeroRealityContext.headers = zeroRealityHeaders;
+        return BookModelPerReality(context)
+            .find({})
+            .populate({ path: 'author', model: AuthorModelPerReality(zeroRealityContext) })
+            .lean();
     } else {
         return BookModelPerReality(context)
             .find({})
diff --git a/test/integration-tests/test-server/schema/schema.ts b/test/integration-tests/test-server/schema/schema.ts
index a5d3593..6078d5a 100644
--- a/test/integration-tests/test-server/schema/schema.ts
+++ b/test/integration-tests/test-server/schema/schema.ts
@@ -1,10 +1,18 @@
 import { GraphQLSchema } from 'graphql';
 import { makeExecutablePolarisSchema } from '../../../../src/main';
 import { resolvers } from './resolvers/book-resolvers';
-import { Book, BookInput, Mutation, Query, Subscription } from './types/schema-types';
+import {
+    Author,
+    AuthorInput,
+    Book,
+    BookInput,
+    Mutation,
+    Query,
+    Subscription,
+} from './types/schema-types';
 
 export const schema: GraphQLSchema = makeExecutablePolarisSchema({
-    typeDefs: [Book, BookInput, Mutation, Query, Subscription],
+    typeDefs: [Author, AuthorInput, Book, BookInput, Mutation, Query, Subscription],
     resolvers: [resolvers],
     resolverValidationOptions: {
         requireResolversForResolveType: false,
diff --git a/test/integration-tests/test-server/schema/types/input/author-input.ts b/test/integration-tests/test-server/schema/types/input/author-input.ts
new file mode 100644
index 0000000..c8341b6
--- /dev/null
+++ b/test/integration-tests/test-server/schema/types/input/author-input.ts
@@ -0,0 +1,10 @@
+export const AuthorInput = `input AuthorInput {
+                            id: ID!,
+                            testId: String!,
+                            firstName: String,
+                            lastName: String
+                          },
+                          input UpdateAuthorInput {
+                            firstName: String,
+                            lastName: String
+                          }`;
diff --git a/test/integration-tests/test-server/schema/types/input/book-input.ts b/test/integration-tests/test-server/schema/types/input/book-input.ts
index 6c8de88..c5cd771 100644
--- a/test/integration-tests/test-server/schema/types/input/book-input.ts
+++ b/test/integration-tests/test-server/schema/types/input/book-input.ts
@@ -2,11 +2,9 @@ export const BookInput = `input BookInput {
                             id: ID,
                             testId: String!,        
                             title: String,
-                            author: String,
-                            otherBook: BookInput
+                            author: AuthorInput,
                           },
                           input UpdateBookInput {
                             title: String,
-                            author: String,
-                            otherBook: BookInput
+                            author: AuthorInput,
                           }`;
diff --git a/test/integration-tests/test-server/schema/types/output/author.ts b/test/integration-tests/test-server/schema/types/output/author.ts
new file mode 100644
index 0000000..cc5744b
--- /dev/null
+++ b/test/integration-tests/test-server/schema/types/output/author.ts
@@ -0,0 +1,9 @@
+export const Author = `type Author implements CommonEntity {
+                        id: ID!
+                        firstName: String,
+                        lastName: String,
+                        creationDate: Date,
+                        lastUpdateDate: Date,
+                        dataVersion: Int!,
+                        realityId: Int!
+                     }`;
diff --git a/test/integration-tests/test-server/schema/types/output/book.ts b/test/integration-tests/test-server/schema/types/output/book.ts
index 9b7abc5..30d99cd 100644
--- a/test/integration-tests/test-server/schema/types/output/book.ts
+++ b/test/integration-tests/test-server/schema/types/output/book.ts
@@ -1,11 +1,10 @@
 export const Book = `type Book implements CommonEntity {
                         testId: String,
                         id: ID!,
+                        title: String,
+                        author: Author,
                         creationDate: Date,
                         lastUpdateDate: Date,
                         dataVersion: Int!,
-                        title: String,
-                        author: String,
-                        otherBook: ID,
                         realityId: Int!
                      }`;
diff --git a/test/integration-tests/test-server/schema/types/schema-types.ts b/test/integration-tests/test-server/schema/types/schema-types.ts
index b5a6f6e..2d9c685 100644
--- a/test/integration-tests/test-server/schema/types/schema-types.ts
+++ b/test/integration-tests/test-server/schema/types/schema-types.ts
@@ -3,3 +3,5 @@ export { Mutation } from './mutation/root-mutation';
 export { Book } from './output/book';
 export { Query } from './query/root-query';
 export { Subscription } from './subscription/root-subscription';
+export { Author } from './output/author';
+export { AuthorInput } from './input/author-input';
diff --git a/test/integration-tests/tests/irrelevant-entities.test.ts b/test/integration-tests/tests/irrelevant-entities.test.ts
index 059058c..4c1b9cc 100644
--- a/test/integration-tests/tests/irrelevant-entities.test.ts
+++ b/test/integration-tests/tests/irrelevant-entities.test.ts
@@ -1,13 +1,13 @@
 import { PolarisRequestHeaders } from '@enigmatis/utills';
-import { graphqlRawRequest, graphqlRequest } from '../test-server/client';
+import { graphqlRawRequest, graphQLRequest } from '../test-server/client';
 import { BookModelPerReality } from '../test-server/dal/book-model';
-import { finish, init } from '../test-server/run-test';
+import { startTestServer, stopTestServer } from '../test-server/run-test';
 export const titles = ['first', 'second', 'third', 'fourth', 'fifth'];
 
 const prepareDb = async (headers: PolarisRequestHeaders) => {
     const books = [];
     for (let i = 0; i < titles.length; i++) {
-        books.push({ author: 'arik', title: titles[i], testId: i, dataVersion: i + 1 });
+        books.push({ title: titles[i], testId: i, dataVersion: i + 1 });
     }
     await BookModelPerReality({ headers }).create(books);
 };
@@ -15,12 +15,12 @@ const prepareDb = async (headers: PolarisRequestHeaders) => {
 const requestHeaders = { 'reality-id': 1, 'data-version': 1 };
 
 beforeEach(async () => {
-    await init();
+    await startTestServer();
     await prepareDb({ realityId: 1 });
 });
 
 afterEach(() => {
-    return finish();
+    return stopTestServer();
 });
 
 describe('irrelevant entities tests', () => {
@@ -89,14 +89,14 @@ describe('irrelevant entities tests', () => {
         const deleteBookMutation = `mutation deleteBook ($bookId:String!) {
          deleteBook(bookId: $bookId){ title }}`;
 
-        const result: any = await graphqlRequest(queryBookStartsWith, requestHeaders, {});
+        const result: any = await graphQLRequest(queryBookStartsWith, requestHeaders);
         const idToDelete = result.booksStartsWith[0].testId;
         const expectedIrrelevantId = result.booksStartsWith[0].id;
-        await graphqlRequest(deleteBookMutation, { 'reality-id': 1 }, { bookId: idToDelete });
+        await graphQLRequest(deleteBookMutation, { 'reality-id': 1 }, { bookId: idToDelete });
         const { extensions }: any = await graphqlRawRequest(queryBookStartsWith, requestHeaders);
 
         expect(
             extensions.irrelevantEntities.booksStartsWith.includes(expectedIrrelevantId),
         ).toBeTruthy();
-    }, 300000);
+    });
 });
diff --git a/test/integration-tests/tests/mutation.test.ts b/test/integration-tests/tests/mutation.test.ts
index 339b1aa..4e32846 100644
--- a/test/integration-tests/tests/mutation.test.ts
+++ b/test/integration-tests/tests/mutation.test.ts
@@ -1,5 +1,5 @@
-import { graphqlRequest } from '../test-server/client';
-import { finish, init } from '../test-server/run-test';
+import { graphQLRequest } from '../test-server/client';
+import { startTestServer, stopTestServer } from '../test-server/run-test';
 
 const headers = { 'reality-id': 1 };
 const createBookMutation = `mutation createBook ($book:BookInput!) {createBook(book:$book){testId}}`;
@@ -9,49 +9,49 @@ const updateBookMutation = `mutation updateBook ($bookId:String!, $update:Update
 const findBookQuery = `query bookById ($bookId:String!) {bookById(bookId:$bookId){title}}`;
 const deleteBookMutation = `mutation deleteBook ($bookId:String!) {
          deleteBook(bookId: $bookId){ title }}`;
-const defaultBookVariables = (title: string, testId: string) => ({ author: 'chen', title, testId });
+const defaultBookVariables = (title: string, testId: string) => ({ title, testId });
 
 beforeEach(() => {
-    return init();
+    return startTestServer();
 });
 
 afterEach(() => {
-    return finish();
+    return stopTestServer();
 });
 
 describe('mutation tests', () => {
     test('create book, book is created ', async () => {
         const id = '1';
         const title = 'book';
-        await graphqlRequest(createBookMutation, headers, {
+        await graphQLRequest(createBookMutation, headers, {
             book: defaultBookVariables(title, id),
         });
-        const response: any = await graphqlRequest(findBookQuery, headers, { bookId: id });
+        const response: any = await graphQLRequest(findBookQuery, headers, { bookId: id });
         expect(response.bookById.title).toEqual(title);
-        await graphqlRequest(deleteBookMutation, headers, { bookId: id });
+        await graphQLRequest(deleteBookMutation, headers, { bookId: id });
     });
     test('update book, book is updated ', async () => {
         const id = '1';
-        await graphqlRequest(createBookMutation, headers, {
+        await graphQLRequest(createBookMutation, headers, {
             book: defaultBookVariables('book', id),
         });
         const updatedTitle = 'book updated';
-        await graphqlRequest(updateBookMutation, headers, {
+        await graphQLRequest(updateBookMutation, headers, {
             bookId: id,
             update: { title: updatedTitle },
         });
-        const response: any = await graphqlRequest(findBookQuery, headers, { bookId: id });
+        const response: any = await graphQLRequest(findBookQuery, headers, { bookId: id });
         expect(response.bookById.title).toEqual(updatedTitle);
-        await graphqlRequest(deleteBookMutation, headers, { bookId: id });
+        await graphQLRequest(deleteBookMutation, headers, { bookId: id });
     });
 
     test('delete book, book is deleted ', async () => {
         const id = '1';
-        await graphqlRequest(createBookMutation, headers, {
+        await graphQLRequest(createBookMutation, headers, {
             book: defaultBookVariables('book', id),
         });
-        await graphqlRequest(deleteBookMutation, headers, { bookId: id });
-        const response: any = await graphqlRequest(findBookQuery, headers, { bookId: id });
+        await graphQLRequest(deleteBookMutation, headers, { bookId: id });
+        const response: any = await graphQLRequest(findBookQuery, headers, { bookId: id });
         expect(response.bookById).toBeNull();
     });
 });
diff --git a/test/integration-tests/tests/query.test.ts b/test/integration-tests/tests/query.test.ts
index 3d72dec..06ed7ef 100644
--- a/test/integration-tests/tests/query.test.ts
+++ b/test/integration-tests/tests/query.test.ts
@@ -1,14 +1,14 @@
 import { PolarisRequestHeaders } from '@enigmatis/utills';
-import { graphqlRequest } from '../test-server/client';
+import { graphQLRequest } from '../test-server/client';
 import { BookModelPerReality } from '../test-server/dal/book-model';
-import { finish, init } from '../test-server/run-test';
+import { startTestServer, stopTestServer } from '../test-server/run-test';
 
 const titles = ['first', 'second', 'third', 'fourth', 'fifth'];
 
 const prepareDb = async (headers: PolarisRequestHeaders) => {
     const books = [];
     for (let i = 0; i < titles.length; i++) {
-        books.push({ author: 'chen', title: titles[i], testId: i });
+        books.push({ title: titles[i], testId: i });
     }
     await BookModelPerReality({ headers }).create(books);
 };
@@ -16,19 +16,19 @@ const prepareDb = async (headers: PolarisRequestHeaders) => {
 const requestHeaders = { 'reality-id': 1 };
 
 beforeEach(async () => {
-    await init();
+    await startTestServer();
     await prepareDb({ realityId: 1 });
 });
 
 afterEach(() => {
-    return finish();
+    return stopTestServer();
 });
 
 describe('query tests', () => {
     test('fetch single book', async () => {
         const queryBook = `query bookById ($bookId:String!) {bookById(bookId:$bookId){title}}`;
         for (let i = 0; i < titles.length; i++) {
-            const response: any = await graphqlRequest(queryBook, requestHeaders, {
+            const response: any = await graphQLRequest(queryBook, requestHeaders, {
                 bookId: i.toString(),
             });
             expect(response.bookById.title).toEqual(titles[i]);
@@ -36,7 +36,7 @@ describe('query tests', () => {
     });
     test('fetch all books', async () => {
         const queryBook = `query{books{title}}`;
-        const response: any = await graphqlRequest(queryBook, requestHeaders, {});
+        const response: any = await graphQLRequest(queryBook, requestHeaders, {});
         const responseTitles = [];
         for (const book of response.books) {
             responseTitles.push(book.title);
diff --git a/test/integration-tests/tests/reality.test.ts b/test/integration-tests/tests/reality.test.ts
new file mode 100644
index 0000000..dc2f19c
--- /dev/null
+++ b/test/integration-tests/tests/reality.test.ts
@@ -0,0 +1,123 @@
+import { graphQLRequest } from '../test-server/client';
+import { AuthorModelPerReality } from '../test-server/dal/author-model';
+import { BookModelPerReality } from '../test-server/dal/book-model';
+import { startTestServer, stopTestServer } from '../test-server/run-test';
+
+const dbRealityIdHeader = (realityId: any) => ({ realityId });
+const requestRealityIdHeader = (realityId: any) => ({ 'reality-id': realityId });
+const realityIdHeaderWithIncludeLinkedOper = (realityId: number) => ({
+    'reality-id': realityId,
+    'include-linked-oper': true,
+});
+
+export const titleArray: string[] = ['first', 'second', 'third', 'fourth', 'fifth'];
+
+const prepareDb = async () => {
+    const firstAuthor = await AuthorModelPerReality({ headers: dbRealityIdHeader(0) }).create({
+        testId: 0,
+        firstName: 'Foo',
+        lastName: 'Bar',
+    });
+
+    const secondAuthor = await AuthorModelPerReality({ headers: dbRealityIdHeader(2) }).create({
+        testId: 0,
+        firstName: 'Hello',
+        lastName: 'World',
+    });
+
+    const books = [];
+    for (let i = 0; i < titleArray.length; i++) {
+        books.push({ testId: i, title: titleArray[i], dataVersion: i + 1 });
+    }
+    await BookModelPerReality({ headers: dbRealityIdHeader(1) }).create(books);
+
+    await BookModelPerReality({ headers: dbRealityIdHeader(3) }).create({
+        testId: 0,
+        title: 'Shadow Realm',
+        author: firstAuthor,
+    });
+
+    await BookModelPerReality({ headers: dbRealityIdHeader(4) }).create({
+        testId: 0,
+        title: 'Lorem Ipsum',
+        author: secondAuthor,
+    });
+};
+
+beforeEach(async () => {
+    await startTestServer();
+    await prepareDb();
+});
+
+afterEach(() => {
+    return stopTestServer();
+});
+
+describe('reality tests', () => {
+    test('fetch entities from specific reality', async () => {
+        const queryBook = `query{books{realityId}}`;
+        const realityId: number = 1;
+        const response: any = await graphQLRequest(queryBook, requestRealityIdHeader(realityId));
+        const responseRealities = [];
+        for (const book of response.books) {
+            responseRealities.push(book.realityId);
+        }
+        const uniqueResponseRealities = [...new Set(responseRealities)];
+        expect(uniqueResponseRealities.length).toBe(1);
+        expect(uniqueResponseRealities).toContain(realityId);
+    });
+
+    test('fetch entities from a non existing reality', async () => {
+        const emptyResult: [] = [];
+        const queryBook = `query{books{realityId}}`;
+        const realityId: number = 999;
+        const response: any = await graphQLRequest(queryBook, requestRealityIdHeader(realityId));
+        expect(response.books).toEqual(emptyResult);
+    });
+
+    test('fetch entities without reality header', async () => {
+        const queryBook = `query{books{title}}`;
+        await expect(graphQLRequest(queryBook, undefined)).rejects.toThrow(
+            'please provide reality-id header',
+        );
+    });
+
+    test('fetch entities with invalid reality header', async () => {
+        const queryBook = `query{books{title}}`;
+        await expect(graphQLRequest(queryBook, requestRealityIdHeader('oops'))).rejects.toThrow(
+            'Unable to format headers',
+        );
+    });
+
+    test('fetch sub entities from specific reality with linked oper entities', async () => {
+        const queryBook = `query{books{realityId author{realityId}}}`;
+        const realityId: number = 3;
+        const response: any = await graphQLRequest(
+            queryBook,
+            realityIdHeaderWithIncludeLinkedOper(realityId),
+        );
+        const responseRealities = [];
+        const responseSubRealities = [];
+        for (const book of response.books) {
+            responseRealities.push(book.realityId);
+            responseSubRealities.push(book.author.realityId);
+        }
+        const uniqueResponseRealities = [...new Set(responseRealities)];
+        const uniqueResponseSubRealities = [...new Set(responseSubRealities)];
+        expect(uniqueResponseRealities.length).toBe(1);
+        expect(uniqueResponseRealities).toContain(realityId);
+        expect(uniqueResponseSubRealities).toContain(0);
+    });
+
+    test('fetch sub entities from specific reality without linked oper entities', async () => {
+        const queryBook = `query{books{realityId title author{realityId}}}`;
+        const realityId: number = 4;
+        const response: any = await graphQLRequest(
+            queryBook,
+            realityIdHeaderWithIncludeLinkedOper(realityId),
+        );
+        for (const book of response.books) {
+            expect(book.author).toBeNull();
+        }
+    });
+});