diff --git a/api/src/__tests__/application.test.ts b/api/src/__tests__/application.test.ts
index 1f12a958b3..decd1472d0 100644
--- a/api/src/__tests__/application.test.ts
+++ b/api/src/__tests__/application.test.ts
@@ -4,7 +4,7 @@ import getNewMissionFixture from "./fixtures/mission";
 import { getNewReferentFixture } from "./fixtures/referent";
 import getNewYoungFixture from "./fixtures/young";
 import getNewCohortFixture from "./fixtures/cohort";
-import getAppHelper from "./helpers/app";
+import getAppHelper, { resetAppAuth } from "./helpers/app";
 import { createApplication, notExistingApplicationId } from "./helpers/application";
 import { dbConnect, dbClose } from "./helpers/db";
 import { notExisitingMissionId, createMissionHelper, getMissionByIdHelper } from "./helpers/mission";
@@ -24,6 +24,7 @@ beforeAll(() => dbConnect(__filename.slice(__dirname.length + 1, -3)));
 afterAll(dbClose);
 
 describe("Application", () => {
+  afterEach(resetAppAuth);
   describe("POST /application", () => {
     it("should return 404 when young is not found", async () => {
       const application = getNewApplicationFixture();
@@ -41,30 +42,25 @@ describe("Application", () => {
       expect(res.status).toBe(404);
     });
     it("should only allow young to apply for themselves", async () => {
-      const lastYear = new Date().getFullYear() - 1;
       const cohort = await createCohortHelper(getNewCohortFixture({ name: "Test" }));
       const young = await createYoungHelper(getNewYoungFixture({ cohort: cohort.name, cohortId: cohort._id, statusPhase1: YOUNG_STATUS_PHASE1.DONE }));
       const secondYoung = await createYoungHelper(getNewYoungFixture({ cohort: cohort.name, cohortId: cohort._id, statusPhase1: YOUNG_STATUS_PHASE1.DONE }));
-      const passport = require("passport");
-      const previous = passport.user;
-      passport.user = young;
+
       const mission = await createMissionHelper(getNewMissionFixture());
       const application = getNewApplicationFixture();
 
       // Successful application
-      let res = await request(getAppHelper())
+      let res = await request(getAppHelper(young))
         .post("/application")
         .send({ ...application, youngId: young._id, missionId: mission._id });
       expect(res.status).toBe(200);
       expect(res.body.data.youngId).toBe(young._id.toString());
 
       // Failed application
-      res = await request(getAppHelper())
+      res = await request(getAppHelper(young))
         .post("/application")
         .send({ ...application, youngId: secondYoung._id, missionId: mission._id });
       expect(res.status).toBe(400);
-
-      passport.user = previous;
     });
     it("should create an application when priority is given", async () => {
       const young = await createYoungHelper(getNewYoungFixture({ cohort: "Test", statusPhase1: YOUNG_STATUS_PHASE1.DONE }));
@@ -118,45 +114,32 @@ describe("Application", () => {
       const year = new Date().getFullYear();
       const cohort = await createCohortHelper(getNewCohortFixture({ name: "Test" }));
       const young = await createYoungHelper(getNewYoungFixture({ cohort: cohort.name, cohortId: cohort._id, birthdateAt: new Date(`${year - 12}-01-01T00:00:00.000Z`) }));
-      const passport = require("passport");
-      const previous = passport.user;
-      passport.user = young;
       const mission = await createMissionHelper(getNewMissionFixture());
       const application = getNewApplicationFixture();
-      const res = await request(getAppHelper())
+      const res = await request(getAppHelper(young))
         .post("/application")
         .send({ ...application, youngId: young._id, missionId: mission._id });
       expect(res.status).toBe(403);
-      passport.user = previous;
     });
     it("should return 403 when cohort is too old", async () => {
       const cohort = await createCohortHelper(getNewCohortFixture({ name: "2019" }));
       const young = await createYoungHelper(getNewYoungFixture({ cohort: cohort.name, cohortId: cohort._id }));
-      const passport = require("passport");
-      const previous = passport.user;
-      passport.user = young;
       const mission = await createMissionHelper(getNewMissionFixture());
       const application = getNewApplicationFixture();
-      const res = await request(getAppHelper())
+      const res = await request(getAppHelper(young))
         .post("/application")
         .send({ ...application, youngId: young._id, missionId: mission._id });
       expect(res.status).toBe(403);
-      passport.user = previous;
     });
     it("should return 403 when young has not finished phase1", async () => {
-      const year = new Date().getFullYear();
       const cohort = await createCohortHelper(getNewCohortFixture({ name: "Test" }));
       const young = await createYoungHelper(getNewYoungFixture({ cohort: cohort.name, cohortId: cohort._id, statusPhase1: YOUNG_STATUS_PHASE1.WAITING_AFFECTATION }));
-      const passport = require("passport");
-      const previous = passport.user;
-      passport.user = young;
       const mission = await createMissionHelper(getNewMissionFixture());
       const application = getNewApplicationFixture();
-      const res = await request(getAppHelper())
+      const res = await request(getAppHelper(young))
         .post("/application")
         .send({ ...application, youngId: young._id, missionId: mission._id });
       expect(res.status).toBe(403);
-      passport.user = previous;
     });
   });
 
@@ -172,9 +155,6 @@ describe("Application", () => {
     it("should only allow young to update for themselves", async () => {
       const young = await createYoungHelper(getNewYoungFixture());
       const secondYoung = await createYoungHelper(getNewYoungFixture());
-      const passport = require("passport");
-      const previous = passport.user;
-      passport.user = young;
       const mission = await createMissionHelper(getNewMissionFixture());
       const application = await createApplication({ ...getNewApplicationFixture(), youngId: young._id, missionId: mission._id });
       const secondApplication = await createApplication({ ...getNewApplicationFixture(), youngId: secondYoung._id, missionId: mission._id });
@@ -184,14 +164,12 @@ describe("Application", () => {
       expect(res.status).toBe(200);
 
       // Failed update (not allowed)
-      res = await request(getAppHelper()).put("/application").send({ priority: "1", status: "DONE", _id: secondApplication._id.toString() });
+      res = await request(getAppHelper(young)).put("/application").send({ priority: "1", status: "DONE", _id: secondApplication._id.toString() });
       expect(res.status).toBe(403);
 
       // Failed update (wrong young id)
-      res = await request(getAppHelper()).put("/application").send({ priority: "1", status: "DONE", _id: application._id.toString(), youngId: secondYoung._id });
+      res = await request(getAppHelper(young)).put("/application").send({ priority: "1", status: "DONE", _id: application._id.toString(), youngId: secondYoung._id });
       expect(res.status).toBe(400);
-
-      passport.user = previous;
     });
 
     it("should update young phase2NumberHoursEstimated and phase2NumberHoursDone", async () => {
@@ -226,9 +204,8 @@ describe("Application", () => {
       expect(res.body.data.status).toBe("WAITING_VALIDATION");
     });
     it("should be only accessible by referent", async () => {
-      const passport = require("passport");
       await request(getAppHelper()).put(`/application/${notExistingApplicationId}`).send();
-      expect(passport.lastTypeCalledOnAuthenticate).toEqual("referent");
+      expect(require("passport").lastTypeCalledOnAuthenticate).toEqual("referent");
     });
   });
 
@@ -281,19 +258,13 @@ describe("Application", () => {
       const secondYoung = await createYoungHelper(getNewYoungFixture());
       const secondApplication = await createApplication({ ...getNewApplicationFixture(), youngId: secondYoung._id, missionId: mission._id });
 
-      const passport = require("passport");
-      const previous = passport.user;
-      passport.user = young;
-
       // Successful request
-      let res = await request(getAppHelper()).post(`/application/${application._id}/notify/${SENDINBLUE_TEMPLATES.referent.NEW_APPLICATION}`).send({});
+      let res = await request(getAppHelper(young)).post(`/application/${application._id}/notify/${SENDINBLUE_TEMPLATES.referent.NEW_APPLICATION}`).send({});
       expect(res.status).toBe(200);
 
       // Failed request (not allowed)
-      res = await request(getAppHelper()).post(`/application/${secondApplication._id}/notify/${SENDINBLUE_TEMPLATES.referent.NEW_APPLICATION}`).send({});
+      res = await request(getAppHelper(young)).post(`/application/${secondApplication._id}/notify/${SENDINBLUE_TEMPLATES.referent.NEW_APPLICATION}`).send({});
       expect(res.status).toBe(403);
-
-      passport.user = previous;
     });
   });
 });
diff --git a/api/src/__tests__/helpers/app.ts b/api/src/__tests__/helpers/app.ts
index 854be65261..176fc9159d 100644
--- a/api/src/__tests__/helpers/app.ts
+++ b/api/src/__tests__/helpers/app.ts
@@ -3,11 +3,23 @@ import express from "express";
 import cookieParser from "cookie-parser";
 import bodyParser from "body-parser";
 import passport from "passport";
+import { Types } from "mongoose";
+const { ObjectId } = Types;
 
 import { injectRoutes } from "../../routes";
 import { UserRequest } from "../../controllers/request";
+import getNewReferentFixture from "../fixtures/referent";
+import { isReferent, isYoung } from "../../utils";
+import { ReferentDocument, YoungDocument } from "../../models";
 
-function getAppHelper(user?: Partial<UserRequest["user"] & { subRole?: any }> | null, authStrategy?: "young" | "referent") {
+export function resetAppAuth() {
+  // @ts-ignore
+  passport.user = getNewReferentFixture();
+  // @ts-ignore
+  passport.user._id = new ObjectId();
+}
+
+function getAppHelper(user?: Partial<UserRequest["user"] & { subRole?: any }> | YoungDocument | ReferentDocument | null, authStrategy?: "young" | "referent") {
   const app = express();
   app.use(bodyParser.json());
   app.use(bodyParser.text({ type: "application/x-ndjson" }));
@@ -22,8 +34,14 @@ function getAppHelper(user?: Partial<UserRequest["user"] & { subRole?: any }> |
       // @ts-ignore
       passport.user = { _id: "123" };
     }
-    // @ts-ignore
-    passport.user = { ...passport.user, ...user };
+    // instance of model
+    if (isYoung(user) || isReferent(user)) {
+      // @ts-ignore
+      passport.user = user;
+    } else {
+      // @ts-ignore
+      passport.user = { ...passport.user, ...user };
+    }
   }
   if (authStrategy) {
     // @ts-ignore