Cannot connect to Oracle database server through SQL Developer but Test works OK

May the reason be why I installed Oracle as desktop class instead of server class?

No, 'Desktop Class' just means you only get basic choices from the installer¹, according to the docs:

• Desktop Class—This installation class is most appropriate for laptop or desktop computers. It includes a starter database and requires minimal configuration.

• Server Class—This installation class is for servers, such as you would find in a data center, or used to support enterprise-level applications. Choose this installation class if you need access to advanced configuration options.

During a Desktop Class installation, you make only basic choices. For a Server Class installation, you choose either typical installation (where you make only basic choices) or advanced installation.

During a Desktop Class or a typical installation, Oracle Database automatically installs the sample schemas.

You'll need to go through the kind of troubleshooting steps suggested in the comments to find out what is causing the ORA-12545 error:

An ORA-12545 error occurs when the client is not able to contact the listener on the node specified. For example: when the listener has not been started on the node, if the node address has been specified incorrectly, or a firewall blocks access.

_{¹ So 'Desktop Class' and 'Server Class' are poor names for the installation types. 'Basic' and 'Custom' might be better?}

you should create at least one database user that you will use to create database objects. A database user is a type of database object: a user is associated with a database schema, you connect to the database as a database user, and the database user is the owner of any database objects (tables and so on) that you create in the schema associated with the user.

For example, to create a database user named chris(For Example). Follow these steps, using the command line:

Display the SQL command prompt window. For example, on Windows, click Start, then Programs (or All Programs), then Oracle Database 11g Express Edition, and then Run SQL Command Line.

Connect as the SYSTEM user:

Type: connect Enter user-name: system Enter password: Create the user. For example, enter a statement in the following form:

SQL> create user chris identified by <password-for-chris>;

Grant the user the necessary privileges. For example:

SQL> grant CREATE SESSION, ALTER SESSION, CREATE DATABASE LINK, -
  CREATE MATERIALIZED VIEW, CREATE PROCEDURE, CREATE PUBLIC SYNONYM, -
  CREATE ROLE, CREATE SEQUENCE, CREATE SYNONYM, CREATE TABLE, - 
  CREATE TRIGGER, CREATE TYPE, CREATE VIEW, UNLIMITED TABLESPACE -
  to chris;

Optionally, exit SQL*Plus (which also closes the command window):

SQL> exit

SQL Developer as an Alternative for Creating Database Users:

If you have experience with SQL Developer, you can use it instead of the command line to create a database user, as follows:

Create a database connection for the SYSTEM user.

Open that database connection for the SYSTEM user.

Right-click the Other Users node in the Connections navigator under that connection.

Select Create User, and specify the necessary information. (Under System Privileges, grant ALTER SESSION, CREATE SESSION, CREATE DATABASE LINK, CREATE MATERIALIZED VIEW, CREATE PROCEDURE, CREATE PUBLIC SYNONYM, CREATE ROLE, CREATE SEQUENCE, CREATE SYNONYM, CREATE TABLE, CREATE TRIGGER, CREATE TYPE, CREATE VIEW, and UNLIMITED TABLESPACE.)

I am also attaching the screen shot with example , which is given by Oracle BOL for SQL Developer connection.

For your ref Here And Here.