diff --git a/src/services/nostrService.js b/src/services/nostrService.js
index 5239273..f881c5c 100644
--- a/src/services/nostrService.js
+++ b/src/services/nostrService.js
@@ -3,13 +3,11 @@ const crypto = require('crypto');
 const { Op } = require('sequelize');
 const { verifyEvent } = require('nostr-tools');
 
-const models = require('../models');
-
-const errors = require('../errors');
-
 class NostrServiceProvider {
-  constructor({ constants }) {
+  constructor({ models, constants, errors }) {
+    this.models = models;
     this.constants = constants;
+    this.errors = errors;
   }
 
   provide() {
@@ -21,7 +19,7 @@ class NostrServiceProvider {
           this.constants.DEFAULT_NOSTR_CHALLENGE_DURATION_SECONDS
       );
 
-      const nostrChallenge = await models.NostrChallengeCreated.create({
+      const nostrChallenge = await this.models.NostrChallengeCreated.create({
         uuid: uuid.v7(),
         challenge: crypto.randomBytes(32).toString('hex'),
         expires_at: expiryTimestamp.toISOString(),
@@ -31,12 +29,12 @@ class NostrServiceProvider {
       return nostrChallenge;
     };
 
-    async function getNostrChallenge(
+    const getNostrChallenge = async (
       nostrChallengeUuid = null,
       challenge = null
-    ) {
+    ) => {
       if (nostrChallengeUuid) {
-        return await models.NostrChallengeCreated.findOne({
+        return await this.models.NostrChallengeCreated.findOne({
           where: {
             uuid: nostrChallengeUuid,
           },
@@ -44,7 +42,7 @@ class NostrServiceProvider {
       }
 
       if (challenge) {
-        return await models.NostrChallengeCreated.findOne({
+        return await this.models.NostrChallengeCreated.findOne({
           where: {
             challenge,
           },
@@ -52,40 +50,40 @@ class NostrServiceProvider {
       }
 
       throw Error('You need to pass a uuid or a challenge.');
-    }
+    };
 
-    async function verifyNostrChallenge(signedEvent) {
+    const verifyNostrChallenge = async (signedEvent) => {
       const challengeTag = signedEvent.tags.find(
         (tag) => tag[0] === 'challenge'
       );
       const challenge = challengeTag[1];
 
       if (!(await isNostrChallengeFresh(challenge))) {
-        throw errors.ExpiredError('Challenge expired, request new one.');
+        throw this.errors.ExpiredError('Challenge expired, request new one.');
       }
 
       if (await hasNostrChallengeBeenCompleted(challenge)) {
-        throw new errors.AlreadyUsedError(
+        throw new this.errors.AlreadyUsedError(
           'Challenge already used, request new one.'
         );
       }
 
       const isSignatureValid = verifyEvent(signedEvent);
       if (!isSignatureValid) {
-        throw new errors.InvalidSignatureError('Signature is not valid.');
+        throw new this.errors.InvalidSignatureError('Signature is not valid.');
       }
 
-      return await models.NostrChallengeCompleted.create({
+      return await this.models.NostrChallengeCompleted.create({
         uuid: uuid.v7(),
         challenge: challenge,
         signed_event: signedEvent,
         public_key: signedEvent.pubkey,
         created_at: new Date().toISOString(),
       });
-    }
+    };
 
-    async function isNostrChallengeFresh(challengeString) {
-      const nostrChallenge = await models.NostrChallengeCreated.findOne({
+    const isNostrChallengeFresh = async (challengeString) => {
+      const nostrChallenge = await this.models.NostrChallengeCreated.findOne({
         where: {
           challenge: challengeString,
           expires_at: {
@@ -98,11 +96,11 @@ class NostrServiceProvider {
         return true;
       }
       return false;
-    }
+    };
 
-    async function hasNostrChallengeBeenCompleted(challengeString) {
+    const hasNostrChallengeBeenCompleted = async (challengeString) => {
       const completedNostrChallenge =
-        await models.NostrChallengeCompleted.findOne({
+        await this.models.NostrChallengeCompleted.findOne({
           where: {
             challenge: challengeString,
           },
@@ -112,7 +110,7 @@ class NostrServiceProvider {
         return true;
       }
       return false;
-    }
+    };
 
     return {
       createNostrChallenge,