diff --git a/lib/constants.test.ts b/lib/constants.test.ts
new file mode 100644
index 0000000..6cc2e6b
--- /dev/null
+++ b/lib/constants.test.ts
@@ -0,0 +1,21 @@
+import { describe, it, expect } from 'vitest'
+import { DEFAULT_TOKEN_SCOPES } from './constants'
+
+describe('constants', () => {
+  describe('DEFAULT_TOKEN_SCOPES', () => {
+    it('should have the correct default token scopes', () => {
+      expect(DEFAULT_TOKEN_SCOPES).toBe('openid profile email offline')
+    })
+
+    it('should be a string', () => {
+      expect(typeof DEFAULT_TOKEN_SCOPES).toBe('string')
+    })
+
+    it('should contain required OpenID scopes', () => {
+      expect(DEFAULT_TOKEN_SCOPES).toContain('openid')
+      expect(DEFAULT_TOKEN_SCOPES).toContain('profile')
+      expect(DEFAULT_TOKEN_SCOPES).toContain('email')
+      expect(DEFAULT_TOKEN_SCOPES).toContain('offline')
+    })
+  })
+})
diff --git a/lib/types.test.ts b/lib/types.test.ts
new file mode 100644
index 0000000..bb02e06
--- /dev/null
+++ b/lib/types.test.ts
@@ -0,0 +1,144 @@
+import { describe, it, expect } from 'vitest'
+import type {
+  LoginSuccessResponse,
+  LoginFailureResponse,
+  LoginResponse,
+  LogoutRequest,
+  LogoutResult,
+  PermissionAccess,
+  Permissions,
+  UserProfile
+} from './types'
+
+describe('types', () => {
+  describe('LoginSuccessResponse', () => {
+    it('should match the expected shape', () => {
+      const response: LoginSuccessResponse = {
+        success: true,
+        accessToken: 'test-access-token',
+        idToken: 'test-id-token'
+      }
+
+      expect(response.success).toBe(true)
+      expect(typeof response.accessToken).toBe('string')
+      expect(typeof response.idToken).toBe('string')
+    })
+  })
+
+  describe('LoginFailureResponse', () => {
+    it('should match the expected shape', () => {
+      const response: LoginFailureResponse = {
+        success: false,
+        errorMessage: 'Login failed'
+      }
+
+      expect(response.success).toBe(false)
+      expect(typeof response.errorMessage).toBe('string')
+    })
+  })
+
+  describe('LoginResponse', () => {
+    it('should accept LoginSuccessResponse', () => {
+      const successResponse: LoginResponse = {
+        success: true,
+        accessToken: 'token',
+        idToken: 'id-token'
+      }
+
+      expect(successResponse.success).toBe(true)
+    })
+
+    it('should accept LoginFailureResponse', () => {
+      const failureResponse: LoginResponse = {
+        success: false,
+        errorMessage: 'Error occurred'
+      }
+
+      expect(failureResponse.success).toBe(false)
+    })
+  })
+
+  describe('LogoutRequest', () => {
+    it('should match the expected shape', () => {
+      const request: LogoutRequest = {
+        revokeToken: true
+      }
+
+      expect(typeof request.revokeToken).toBe('boolean')
+    })
+  })
+
+  describe('LogoutResult', () => {
+    it('should match the expected shape', () => {
+      const result: LogoutResult = {
+        success: true
+      }
+
+      expect(typeof result.success).toBe('boolean')
+    })
+  })
+
+  describe('PermissionAccess', () => {
+    it('should match the expected shape', () => {
+      const permission: PermissionAccess = {
+        permissionKey: 'read:users',
+        orgCode: 'org_123',
+        isGranted: true
+      }
+
+      expect(typeof permission.permissionKey).toBe('string')
+      expect(typeof permission.orgCode).toBe('string')
+      expect(typeof permission.isGranted).toBe('boolean')
+    })
+
+    it('should allow null orgCode', () => {
+      const permission: PermissionAccess = {
+        permissionKey: 'read:users',
+        orgCode: null,
+        isGranted: false
+      }
+
+      expect(permission.orgCode).toBeNull()
+    })
+  })
+
+  describe('Permissions', () => {
+    it('should match the expected shape', () => {
+      const permissions: Permissions = {
+        orgCode: 'org_123',
+        permissions: ['read:users', 'write:users']
+      }
+
+      expect(typeof permissions.orgCode).toBe('string')
+      expect(Array.isArray(permissions.permissions)).toBe(true)
+      expect(permissions.permissions.every(p => typeof p === 'string')).toBe(true)
+    })
+
+    it('should allow null orgCode', () => {
+      const permissions: Permissions = {
+        orgCode: null,
+        permissions: ['global:permission']
+      }
+
+      expect(permissions.orgCode).toBeNull()
+    })
+  })
+
+  describe('UserProfile', () => {
+    it('should match the expected shape with all fields', () => {
+      const user: UserProfile = {
+        id: 'user_123',
+        givenName: 'John',
+        familyName: 'Doe',
+        email: 'john.doe@example.com',
+        picture: 'https://example.com/avatar.jpg'
+      }
+
+      expect(typeof user.id).toBe('string')
+      expect(typeof user.givenName).toBe('string')
+      expect(typeof user.familyName).toBe('string')
+      expect(typeof user.email).toBe('string')
+      expect(typeof user.picture).toBe('string')
+    })
+  })
+})
diff --git a/vitest.config.ts b/vitest.config.ts
new file mode 100644
index 0000000..bfd10aa
--- /dev/null
+++ b/vitest.config.ts
@@ -0,0 +1,25 @@
+import { defineConfig } from 'vitest/config'
+
+export default defineConfig({
+  test: {
+    environment: 'node',
+    coverage: {
+      provider: 'v8',
+      reporter: ['text', 'json', 'html'],
+      exclude: [
+        'node_modules/',
+        'dist/',
+        'test-kinde-expo/',
+        '**/*.d.ts',
+        'vite.config.ts',
+        'vitest.config.ts',
+        'eslint.config.js'
+      ]
+    },
+    include: ['lib/**/*.{test,spec}.{js,mjs,cjs,ts,mts,cts,jsx,tsx}'],
+    exclude: ['node_modules/', 'dist/', 'test-kinde-expo/', '.git/']
+  },
+  resolve: {
+    alias: { '@': '/lib' }
+  }
+})