Adding a test to demonstrate programmatic registration.

testing-modules/junit-5/src/test/java/com/baeldung/ProgrammaticEmployeesUnitTest.java

@@ -0,0 +1,42 @@
+package com.baeldung;
+
+import java.sql.SQLException;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import com.baeldung.helpers.Employee;
+import com.baeldung.extensions.EmployeeDaoParameterResolver;
+import com.baeldung.extensions.EmployeeDatabaseSetupExtension;
+import com.baeldung.extensions.EnvironmentExtension;
+import com.baeldung.helpers.EmployeeJdbcDao;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+@ExtendWith({ EnvironmentExtension.class, EmployeeDaoParameterResolver.class })
+public class ProgrammaticEmployeesUnitTest {
+
+    private EmployeeJdbcDao employeeDao;
+
+    @RegisterExtension static EmployeeDatabaseSetupExtension DB =
+            new EmployeeDatabaseSetupExtension("jdbc:h2:mem:AnotherDb;DB_CLOSE_DELAY=-1", "org.h2.Driver", "sa", "");
+
+    public ProgrammaticEmployeesUnitTest(EmployeeJdbcDao employeeDao) {
+        this.employeeDao = employeeDao;
+    }
+
+    @Test
+    public void whenAddEmployee_thenGetEmployee() throws SQLException {
+        Employee emp = new Employee(1, "john");
+        employeeDao.add(emp);
+        assertEquals(1, employeeDao.findAll()
+                .size());
+    }
+
+    @Test
+    public void whenGetEmployees_thenEmptyList() throws SQLException {
+        assertEquals(0, employeeDao.findAll()
+                .size());
+    }
+}

testing-modules/junit-5/src/test/java/com/baeldung/helpers/JdbcConnectionUtil.java

@@ -11,7 +11,7 @@ public class JdbcConnectionUtil {
     private static Connection con;
 
     public static Connection getConnection() {
-        if (con == null) {
+        if (con == null || isClosed(con)) {
             try {
                 Properties props = new Properties();
                 props.load(JdbcConnectionUtil.class.getResourceAsStream("jdbc.properties"));
@@ -32,7 +32,7 @@ public class JdbcConnectionUtil {
     }
 
     public static Connection getConnection(String jdbcUrl, String driver, String username, String password) {
-        if (con == null) {
+        if (con == null || isClosed(con)) {
             try {
                 Class.forName(driver);
                 con = DriverManager.getConnection(jdbcUrl, username, password);
@@ -48,4 +48,12 @@ public class JdbcConnectionUtil {
 
         return con;
     }
+
+    private static boolean isClosed(Connection con) {
+        try {
+            return con.isClosed();
+        } catch (SQLException e) {
+            return true;
+        }
+    }
 }