Update plugins/node/opentelemetry-instrumentation-mysql2/test/mysql.test.ts

Co-authored-by: Marc Pichler <[email protected]>

Author: macno

plugins/node/opentelemetry-instrumentation-mysql2/test/mysql.test.ts

@@ -1250,7 +1250,10 @@ describe('mysql2', () => {
     let mysqlTypesPromReload: typeof mysqlTypesProm;
 
     before(async function () {
-      // cleanup cache for mysql2
+      // cleanup cache for 'mysql2'
+      // in previous iterations these tests would have passed since 'mysql2' was already loaded,
+      // but 'mysql2/promise' does not import 'mysql2'. Therefore, if used without ever loading 'mysql2',
+      // the relevant code would never get patched.
       delete require.cache[require.resolve('../src')];
       Object.keys(require.cache).forEach(key => {
         if (key.includes('mysql2/')) {