Test option compatibility with simple-oauth2 (#229)

This is an alternative to #225 where rather than using `@types/simple-oauth2` in the published types we ensure at test time that the local types are indeed compatible with the published types of `@types/simple-oauth2`.

That way a consumer that wants to have access to the full types of `simple-oauth2` can add `@types/simple-oauth2` in their own project, knowing that it will be compatible

Author: voxpelli

package.json

@@ -29,6 +29,7 @@
   "devDependencies": {
     "@fastify/pre-commit": "^2.0.2",
     "@types/node": "^20.5.3",
+    "@types/simple-oauth2": "^5.0.4",
     "fastify": "^4.21.0",
     "nock": "^13.3.3",
     "simple-get": "^4.0.1",

types/index.test-d.ts

@@ -7,6 +7,7 @@ import fastifyOauth2, {
     OAuth2Token,
     ProviderConfiguration
 } from '..';
+import type { ModuleOptions } from 'simple-oauth2';
 
 /**
  * Preparing some data for testing.
@@ -22,6 +23,14 @@ const credentials: Credentials = {
     auth: auth,
 };
 
+const simpleOauth2Options: ModuleOptions = {
+    client: {
+        id: 'test_id',
+        secret: 'test_secret',
+    },
+    auth: auth,
+};
+
 const OAuth2NoneOptional: FastifyOAuth2Options = {
     name: 'testOAuthName',
     credentials: credentials,
@@ -84,6 +93,13 @@ expectType<string[]>(scope);
 expectType<string[]>(tags);
 expectType<Credentials>(credentials);
 
+// Ensure duplicayed simple-oauth2 are compatible with simple-oauth2
+expectAssignable<ModuleOptions<string>>(credentials);
+expectAssignable<ModuleOptions["auth"]>(auth);
+// Ensure published types of simple-oauth2 are accepted
+expectAssignable<Credentials>(simpleOauth2Options);
+expectAssignable<ProviderConfiguration>(simpleOauth2Options.auth);
+
 expectError(fastifyOauth2()); // error because missing required arguments
 expectError(fastifyOauth2(server, {}, () => {
 })); // error because missing required options