diff --git a/packages/core/src/test/index.spec.ts b/packages/core/src/test/index.spec.ts
index fec00633..d82d5e3e 100644
--- a/packages/core/src/test/index.spec.ts
+++ b/packages/core/src/test/index.spec.ts
@@ -1,19 +1,8 @@
 import { SDJwtInstance, SdJwtPayload } from '../index';
-import { DisclosureFrame, Signer, Verifier } from '@sd-jwt/types';
+import { Signer, Verifier } from '@sd-jwt/types';
 import Crypto from 'node:crypto';
 import { describe, expect, test } from 'vitest';
 import { digest, generateSalt } from '@sd-jwt/crypto-nodejs';
-import exp from 'node:constants';
-
-export class TestInstance extends SDJwtInstance<SdJwtPayload> {
-  protected type = 'sd-jwt';
-
-  protected validateReservedFields(
-    disclosureFrame: DisclosureFrame<SdJwtPayload>,
-  ): void {
-    return;
-  }
-}
 
 export const createSignerVerifier = () => {
   const { privateKey, publicKey } = Crypto.generateKeyPairSync('ed25519');
@@ -34,13 +23,13 @@ export const createSignerVerifier = () => {
 
 describe('index', () => {
   test('create', async () => {
-    const sdjwt = new TestInstance();
+    const sdjwt = new SDJwtInstance<SdJwtPayload>();
     expect(sdjwt).toBeDefined();
   });
 
   test('kbJwt', async () => {
     const { signer, verifier } = createSignerVerifier();
-    const sdjwt = new TestInstance({
+    const sdjwt = new SDJwtInstance<SdJwtPayload>({
       signer,
       signAlg: 'EdDSA',
       verifier,
@@ -78,7 +67,7 @@ describe('index', () => {
 
   test('issue', async () => {
     const { signer, verifier } = createSignerVerifier();
-    const sdjwt = new TestInstance({
+    const sdjwt = new SDJwtInstance<SdJwtPayload>({
       signer,
       signAlg: 'EdDSA',
       verifier,
@@ -112,7 +101,7 @@ describe('index', () => {
       );
     };
 
-    const sdjwt = new TestInstance({
+    const sdjwt = new SDJwtInstance<SdJwtPayload>({
       signer,
       signAlg: 'EdDSA',
       verifier: failedverifier,
@@ -150,7 +139,7 @@ describe('index', () => {
         Buffer.from(sig, 'base64url'),
       );
     };
-    const sdjwt = new TestInstance({
+    const sdjwt = new SDJwtInstance<SdJwtPayload>({
       signer,
       signAlg: 'EdDSA',
       verifier,
@@ -192,7 +181,7 @@ describe('index', () => {
 
   test('verify with kbJwt', async () => {
     const { signer, verifier } = createSignerVerifier();
-    const sdjwt = new TestInstance({
+    const sdjwt = new SDJwtInstance<SdJwtPayload>({
       signer,
       signAlg: 'EdDSA',
       verifier,
@@ -230,7 +219,7 @@ describe('index', () => {
   });
 
   test('Hasher not found', async () => {
-    const sdjwt = new TestInstance({});
+    const sdjwt = new SDJwtInstance<SdJwtPayload>({});
     try {
       const credential = await sdjwt.issue(
         {
@@ -251,7 +240,7 @@ describe('index', () => {
   });
 
   test('SaltGenerator not found', async () => {
-    const sdjwt = new TestInstance({
+    const sdjwt = new SDJwtInstance<SdJwtPayload>({
       hasher: digest,
     });
     try {
@@ -274,7 +263,7 @@ describe('index', () => {
   });
 
   test('Signer not found', async () => {
-    const sdjwt = new TestInstance({
+    const sdjwt = new SDJwtInstance<SdJwtPayload>({
       hasher: digest,
       saltGenerator: generateSalt,
     });
@@ -299,7 +288,7 @@ describe('index', () => {
 
   test('Verifier not found', async () => {
     const { signer, verifier } = createSignerVerifier();
-    const sdjwt = new TestInstance({
+    const sdjwt = new SDJwtInstance<SdJwtPayload>({
       signer,
       hasher: digest,
       saltGenerator: generateSalt,
@@ -339,7 +328,7 @@ describe('index', () => {
 
   test('kbSigner not found', async () => {
     const { signer, verifier } = createSignerVerifier();
-    const sdjwt = new TestInstance({
+    const sdjwt = new SDJwtInstance<SdJwtPayload>({
       signer,
       verifier,
       hasher: digest,
@@ -377,7 +366,7 @@ describe('index', () => {
 
   test('kbVerifier not found', async () => {
     const { signer, verifier } = createSignerVerifier();
-    const sdjwt = new TestInstance({
+    const sdjwt = new SDJwtInstance<SdJwtPayload>({
       signer,
       verifier,
       hasher: digest,
@@ -417,7 +406,7 @@ describe('index', () => {
 
   test('kbSignAlg not found', async () => {
     const { signer, verifier } = createSignerVerifier();
-    const sdjwt = new TestInstance({
+    const sdjwt = new SDJwtInstance<SdJwtPayload>({
       signer,
       verifier,
       hasher: digest,
@@ -454,7 +443,7 @@ describe('index', () => {
 
   test('hasher is not found', async () => {
     const { signer } = createSignerVerifier();
-    const sdjwt_create = new TestInstance({
+    const sdjwt_create = new SDJwtInstance<SdJwtPayload>({
       signer,
       hasher: digest,
       saltGenerator: generateSalt,
@@ -471,7 +460,7 @@ describe('index', () => {
         _sd: ['foo'],
       },
     );
-    const sdjwt = new TestInstance({});
+    const sdjwt = new SDJwtInstance<SdJwtPayload>({});
     expect(sdjwt.keys('')).rejects.toThrow('Hasher not found');
     expect(sdjwt.presentableKeys('')).rejects.toThrow('Hasher not found');
     expect(sdjwt.getClaims('')).rejects.toThrow('Hasher not found');
@@ -483,7 +472,7 @@ describe('index', () => {
 
   test('presentableKeys', async () => {
     const { signer } = createSignerVerifier();
-    const sdjwt = new TestInstance({
+    const sdjwt = new SDJwtInstance<SdJwtPayload>({
       signer,
       hasher: digest,
       saltGenerator: generateSalt,
diff --git a/packages/core/test/app-e2e.spec.ts b/packages/core/test/app-e2e.spec.ts
index a44ca89d..653522a3 100644
--- a/packages/core/test/app-e2e.spec.ts
+++ b/packages/core/test/app-e2e.spec.ts
@@ -6,16 +6,6 @@ import path from 'path';
 import { describe, expect, test } from 'vitest';
 import { digest, generateSalt } from '@sd-jwt/crypto-nodejs';
 
-export class TestInstance extends SDJwtInstance<SdJwtPayload> {
-  protected type = 'sd-jwt';
-
-  protected validateReservedFields(
-    disclosureFrame: DisclosureFrame<SdJwtPayload>,
-  ): void {
-    return;
-  }
-}
-
 export const createSignerVerifier = () => {
   const { privateKey, publicKey } = Crypto.generateKeyPairSync('ed25519');
   const signer: Signer = async (data: string) => {
@@ -36,7 +26,7 @@ export const createSignerVerifier = () => {
 describe('App', () => {
   test('Example', async () => {
     const { signer, verifier } = createSignerVerifier();
-    const sdjwt = new TestInstance({
+    const sdjwt = new SDJwtInstance<SdJwtPayload>({
       signer,
       signAlg: 'EdDSA',
       verifier,
@@ -202,7 +192,7 @@ describe('App', () => {
 async function JSONtest(filename: string) {
   const test = loadTestJsonFile(filename);
   const { signer, verifier } = createSignerVerifier();
-  const sdjwt = new TestInstance({
+  const sdjwt = new SDJwtInstance<SdJwtPayload>({
     signer,
     signAlg: 'EdDSA',
     verifier,