diff --git a/src/application/config/autoload.php b/src/application/config/autoload.php
index 17c50920..20541f46 100644
--- a/src/application/config/autoload.php
+++ b/src/application/config/autoload.php
@@ -64,7 +64,7 @@ $autoload['libraries'] = array('database');
 |	$autoload['helper'] = array('url', 'file');
 */
 
-$autoload['helper'] = array();
+$autoload['helper'] = array('custom_exceptions');
 
 
 /*
diff --git a/src/application/libraries/Unit_tests/Unit_tests.php b/src/application/libraries/Unit_tests/Unit_tests.php
index 7848429e..e65180cd 100644
--- a/src/application/libraries/Unit_tests/Unit_tests.php
+++ b/src/application/libraries/Unit_tests/Unit_tests.php
@@ -19,7 +19,8 @@ class Unit_tests extends CI_Driver_Library {
         // Add more subclasses to the following array to expand
         // the unit testing classes.
         $this->valid_drivers = array(
-            'Unit_tests_appointments_model'
+            'Unit_tests_appointments_model',
+            'Unit_tests_customers_model'
         );
     }
     
@@ -31,8 +32,9 @@ class Unit_tests extends CI_Driver_Library {
      * be run.
      */
     public function run_all_tests() {
-        $this->run_model_tests();
-        $this->run_library_tests();
+        $this->run_model_tests(false);
+        $this->run_library_tests(false);
+        $this->CI->output->append_output($this->CI->unit->report());
     }
     
     ///////////////////////////////////////////////////////////////////////////
@@ -40,15 +42,30 @@ class Unit_tests extends CI_Driver_Library {
     ///////////////////////////////////////////////////////////////////////////
     /**
      * Run all the models tests.
+     * 
+     * @param bool $output_report Determines wether the test 
+     * report will be outputted.
      */
-    public function run_model_tests() {
+    public function run_model_tests($output_report = true) {
         $this->appointments_model->run_all();
+        $this->customers_model->run_all();
+        
+        if ($output_report) {
+            $this->CI->output->append_output($this->CI->unit->report());
+        }
     }
     
     /**
      * Run all the library tests.
+     * 
+     * @param bool $output_report Determines wether the test 
+     * report will be outputted.
      */
-    public function run_library_tests() {
+    public function run_library_tests($output_report = true) {
+        // @task Implement unit tests for the libraries.
         
+        if ($output_report) {
+            $this->CI->output->append_output($this->CI->unit->report());
+        }
     }   
 }
\ No newline at end of file
diff --git a/src/application/libraries/Unit_tests/drivers/Unit_tests_appointments_model.php b/src/application/libraries/Unit_tests/drivers/Unit_tests_appointments_model.php
index b46fd542..0ba9a5a5 100644
--- a/src/application/libraries/Unit_tests/drivers/Unit_tests_appointments_model.php
+++ b/src/application/libraries/Unit_tests/drivers/Unit_tests_appointments_model.php
@@ -47,13 +47,10 @@ class Unit_tests_appointments_model extends CI_Driver {
         // "test" keyword from the beginning.
         $class_methods = get_class_methods('Unit_tests_appointments_model');
         foreach ($class_methods as $method_name) {
-            if (strpos($method_name, 'test_') !== FALSE) {
+            if (substr($method_name, 0, 5) === 'test_') {
                 call_user_func(array($this, $method_name));
             }
         }
-        
-        // Create a report on the browser.
-        $this->CI->output->append_output($this->CI->unit->report());
     }
     
     /////////////////////////////////////////////////////////////////////////
@@ -191,10 +188,414 @@ class Unit_tests_appointments_model extends CI_Driver {
         $this->CI->unit->run($this->CI->Appointments_Model->exists($appointment_data), FALSE, 'Test exists() method with wrong appointment data.');
     }
     
-    // @task Test find_record_id
-    // @task Test delete 
-    // @task Test get_batch
-    // @task Test get_row
-    // @task Test get_value
-    // @task Test validate_data
-}
\ No newline at end of file
+    /**
+     * Test the find record id method with a record that already 
+     * exists in the databse.
+     */
+    private function test_find_record_id() {
+        // Create a new appointmnet record.
+        $appointment_data = array(
+                               'start_datetime' => '2013-05-01 12:30:00',
+                               'end_datetime' => '2013-05-01 13:00:00',
+                               'notes' => 'Some notes right here...',
+                               'id_users_provider' => $this->provider_id,
+                               'id_users_customer' => $this->customer_id,
+                               'id_services' => $this->service_id
+                           );
+        $this->CI->db->insert('ea_appointments', $appointment_data);
+        $appointment_data['id'] = $this->CI->db->insert_id();
+        
+        // Find record id of the new appointment record.
+        $method_result_id = $this->CI->Appointments_Model->find_record_id($appointment_data);
+        
+        $this->CI->unit->run($method_result_id, $appointment_data['id'], 'Test find_record_id() successfully returned the correct record id.');
+        
+        // Delete appointment record.
+        $this->CI->db->delete('ea_appointments', array('id' => $method_result_id));
+    }
+    
+    /**
+     * Try to find the record id of an appointment that doesn't
+     * exist in the database.
+     * 
+     * A database exception is expected to be raised.
+     */
+    private function test_find_record_id_appointment_does_not_exist() {
+        // Define appointment data. These data shouldn't exist in the database.
+        $appointment_data = array(
+                               'start_datetime' => '2013-05-01 12:30:00',
+                               'end_datetime' => '2013-05-01 13:00:00',
+                               'notes' => 'Some notes right here...',
+                               'id_users_provider' => $this->provider_id,
+                               'id_users_customer' => $this->customer_id,
+                               'id_services' => $this->service_id
+                           );
+        
+        // Load the appointments model and execute the find record id method.
+        $hasThrownException = FALSE;
+        
+        try {
+            $this->CI->Appointments_Model->find_record_id($appointment_data);
+        } catch(DatabaseException $dbExc) {
+            $hasThrownException = TRUE;
+        }
+        
+        $this->CI->unit->run($hasThrownException, TRUE, 'Test find_record_id() with appointment ' 
+                . 'data that does not exist in the database.', 'A database exception is expected '
+                . 'to be raised.');
+    }
+    
+    /**
+     * Test the find_record_id() method by providing wrong
+     * appointment data.
+     * 
+     * A database exception is expected to be raised.
+     */
+    private function test_find_record_id_wrong_data() {
+        // Define appointment data array with wrong values.
+        $appointment_data = array(
+                               'start_datetime' => '2013WRONG-05-0WRONG1 12:WRONG30:00',
+                               'end_datetime' => '2013-05-01 13:00:00WRONG',
+                               'notes' => 'Some notes righWRONGt here...',
+                               'id_users_provider' => 'WRONG',
+                               'id_users_customer' => 'WRONG',
+                               'id_services' => 'WRONG'
+                           );
+        
+        // Try to find the appointmet's record id. A database 
+        // exception should be raised.
+        $hasThrownException = FALSE;
+        
+        try {
+            $this->CI->Appointments_Model->find_record_id($appointment_data);
+        } catch(DatabaseException $dbExc) {
+            $hasThrownException = TRUE;
+        }
+        
+        $this->CI->unit->run($hasThrownException, TRUE, 'Test find_record_id() with appointment ' 
+                . 'data array with wrong values.', 'A database exception is expected to be raised.');
+    } 
+    
+    /**
+     * Test the normal flow of deleting an appointment record.
+     */
+    private function test_delete() {
+        // Create a new appointmnet record.
+        $appointment_data = array(
+                               'start_datetime' => '2013-05-01 12:30:00',
+                               'end_datetime' => '2013-05-01 13:00:00',
+                               'notes' => 'Some notes right here...',
+                               'id_users_provider' => $this->provider_id,
+                               'id_users_customer' => $this->customer_id,
+                               'id_services' => $this->service_id
+                           );
+        $this->CI->db->insert('ea_appointments', $appointment_data);
+        $appointment_data['id'] = $this->CI->db->insert_id();
+        
+        // Delete new record
+        $delete_result = $this->CI->Appointments_Model->delete($appointment_data['id']);
+        $this->CI->unit->run($delete_result, TRUE, 'Test delete() method result (should be TRUE).');
+        
+        // Check if the record has been successfully deleted.
+        $num_rows = $this->CI->db->get_where('ea_appointments', array('id' => $appointment_data['id']))->num_rows();
+        $this->CI->unit->run($num_rows, 0, 'Test if the record was successfully deleted.');
+    }
+    
+    /**
+     * Test the delete method with a record that doesn't exist
+     * in the database.
+     */
+    private function test_delete_record_does_not_exist() {
+        $random_record_id = 1233265;
+        
+        $delete_result = $this->CI->Appointments_Model->delete($random_record_id);
+        echo $delete_result;
+        $this->CI->unit->run($delete_result, FALSE, 'Test delete() method with a record id' 
+                . ' that does not exist');
+    }
+    
+    /**
+     * Test the delete method by providing a wrong argument 
+     * (string and not integer).
+     */
+    private function test_delete_record_wrong_parameter_given() {
+        $wrong_record_id = 'not_an_integer';
+        
+        $delete_result = $this->CI->Appointments_Model->delete($wrong_record_id);
+        echo $delete_result;
+        $this->CI->unit->run($delete_result, FALSE, 'Test delete() method with a record id' 
+                . ' that is not an integer');
+    }
+    
+    /**
+     * Test the get_batch() method of the appointments model.
+     */
+    private function test_get_batch() {
+        // Get all the appointment records (without using the model).
+        $db_data = $this->CI->db->get('ea_appointments')->result_array();
+        
+        // Get all the appointment records (by using the model).
+        $model_data = $this->CI->Appointments_Model->get_batch();
+        
+        // Check that the two arrays are the same.
+        $this->CI->unit->run($model_data, $db_data, 'Test get_batch() method.');
+    }
+    
+    /**
+     * Test the get_batch() method of the appointments model
+     * with a where clause.
+     */
+    private function test_get_batch_where_clause() {
+        // Insert new appointment.
+        $appointment_data = array(
+                               'start_datetime' => '2013-05-01 12:30:00',
+                               'end_datetime' => '2013-05-01 13:00:00',
+                               'notes' => 'Some notes right here...',
+                               'id_users_provider' => $this->provider_id,
+                               'id_users_customer' => $this->customer_id,
+                               'id_services' => $this->service_id
+                           );
+        $this->CI->db->insert('ea_appointments', $appointment_data);
+        $appointment_data['id'] = $this->CI->db->insert_id();
+        
+        // Get filtered appointment records without using the model.
+        $db_data = $this->CI->db->get_where('ea_appointments', array('id' => $appointment_data['id']))->result_array();
+        
+        // Get filtered appointment records by using the model.
+        $model_data = $this->CI->Appointments_Model->get_batch(array('id' => $appointment_data['id']));
+        
+        // Check that the two arrays are the same.
+        $this->CI->unit->run($model_data, $db_data, 'Test get_batch() method.');
+        
+        // Delete appointment record.
+        $this->CI->db->delete('ea_appointments', array('id' => $appointment_data['id']));
+    }
+    
+    /**
+     * Test the get_batch() method of the appointments model
+     * with a wrong where clause. 
+     * 
+     * A database exception is expected to be raised.
+     * 
+     * <strong>IMPORTANT!</strong> This test is unabled because code
+     * igniter handles itself wrong queries.
+     */
+    private function unabled_test_get_batch_wrong_where_clause() {
+        $hasThrownException = FALSE;
+        
+        try {
+            $this->CI->Appointments_Model->get_batch('WRONG QUERY HERE');
+        } catch(DatabaseException $dbExc) {
+            $hasThrownException = TRUE;
+        }
+        
+        $this->CI->unit->run($hasThrownException, TRUE, 'Test get_batch() with wrong where clause.',
+                'A database excpetion is expected to be thrown.');
+    }
+    
+    /**
+     * Test get_row() method.
+     */
+    private function test_get_row() {
+        // Insert new appointment record.
+        $appointment_data = array(
+                               'start_datetime' => '2013-05-01 12:30:00',
+                               'end_datetime' => '2013-05-01 13:00:00',
+                               'notes' => 'Some notes right here...',
+                               'id_users_provider' => $this->provider_id,
+                               'id_users_customer' => $this->customer_id,
+                               'id_services' => $this->service_id
+                           );
+        $this->CI->db->insert('ea_appointments', $appointment_data);
+        $appointment_data['id'] = $this->CI->db->insert_id();
+        
+        // Get the appointment row from the database.
+        $db_data = $this->CI->Appointments_Model->get_row($appointment_data['id']);
+                
+        // Check if this is the record we seek.
+        $this->CI->unit->run($db_data, $appointment_data, 'Test get_row() method.');
+        
+        // Delete appointment record.
+        $this->CI->db->delete('ea_appointments', array('id' => $appointment_data['id']));
+    }
+    
+    /**
+     * Test get_row() with a record that doesn't exist in the db.
+     */
+    private function test_get_row_that_does_not_exist() {
+        $random_record_id = 789453486;
+        
+        $row_data = $this->CI->Appointments_Model->get_row($random_record_id);
+        
+        $this->CI->unit->run($row_data, NULL, 'Test get_row() with record id that does ' 
+                . 'not exist in the database.');
+    }
+    
+    /**
+     * Test get_row() method with wrong argument.
+     * 
+     * A database exception is expected.
+     */
+    private function test_get_row_wrong_argument_given() {
+        $wrong_arguement_id = 'THIS IS NOT AN INTEGER';
+        
+        $hasThrownException = FALSE;
+        try {
+            $this->CI->Appointments_Model->get_row($wrong_arguement_id);        
+        } catch (DatabaseException $dbExc) {
+            $hasThrownException = TRUE;
+        }
+        
+        $this->CI->unit->run($hasThrownException, TRUE, 'Test get_row() with wrong arguement.');
+    }
+    
+    /**
+     * Test the get field value method.
+     */
+    private function test_get_value() {
+        // Insert new appointment record.
+        $appointment_data = array(
+                               'start_datetime' => '2013-05-01 12:30:00',
+                               'end_datetime' => '2013-05-01 13:00:00',
+                               'notes' => 'Some notes right here...',
+                               'id_users_provider' => $this->provider_id,
+                               'id_users_customer' => $this->customer_id,
+                               'id_services' => $this->service_id
+                           );
+        $this->CI->db->insert('ea_appointments', $appointment_data);
+        $appointment_data['id'] = $this->CI->db->insert_id();
+        
+        // Get a specific value from the database.
+        
+        $db_value = $this->CI->Appointments_Model->get_value('start_datetime', $appointment_data['id']);
+        
+        // Check if the value was correctly fetched from the database.
+        $this->CI->unit->run($db_value, $appointment_data['start_datetime'], 'Test get_value() method.');
+        
+        // Delete inserted appointment record.
+        $this->CI->db->delete('ea_appointments', array('id' => $appointment_data['id']));
+    }
+    
+    /**
+     * Test the get field value method with a record id that
+     * doesn't exist in the db.
+     * 
+     * A database exception is expected.
+     */
+    private function test_get_value_record_does_not_exist() {
+        $random_record_id = 843521368768;
+        
+        $hasThrownException = FALSE;
+        
+        try {
+            $this->CI->Appointments_Model->get_value('start_datetime', $random_record_id);
+        } catch (DatabaseException $dbExc) {
+            $hasThrownException = TRUE;
+        }
+        
+        $this->CI->unit->run($hasThrownException, TRUE, 'Test get_value() with record id that does not exist.');
+    }
+    
+    /**
+     * Test the get_value() method with a field that does 
+     * not exist in the db.
+     * 
+     * A database exception is expected.
+     */
+    private function test_get_value_field_does_not_exist() {
+        // Insert new appointment record.
+        $appointment_data = array(
+                               'start_datetime' => '2013-05-01 12:30:00',
+                               'end_datetime' => '2013-05-01 13:00:00',
+                               'notes' => 'Some notes right here...',
+                               'id_users_provider' => $this->provider_id,
+                               'id_users_customer' => $this->customer_id,
+                               'id_services' => $this->service_id
+                           );
+        $this->CI->db->insert('ea_appointments', $appointment_data);
+        $appointment_data['id'] = $this->CI->db->insert_id();
+        
+        // Try to get record value with wrong field name.
+        $wrong_field_name = 'THIS IS WRONG';
+        $hasThrownException = FALSE;
+        
+        try {
+            $this->CI->Appointments_Model->get_value($wrong_field_name, $appointment_data['id']);
+        } catch (DatabaseException $dbExc) {
+            $hasThrownException = TRUE;
+        }
+        
+        $this->CI->unit->run($hasThrownException, TRUE, 'Test get_value() with record id that does not exist.');
+        
+        // Delete inserted record.
+        $this->CI->db->delete('ea_appointments', array('id' => $appointment_data['id']));
+    }
+    
+    private function test_validate_data() {
+        $appointment_data = array(
+                               'start_datetime' => '2013-05-01 12:30:00',
+                               'end_datetime' => '2013-05-01 13:00:00',
+                               'notes' => 'Some notes right here...',
+                               'id_users_provider' => $this->provider_id,
+                               'id_users_customer' => $this->customer_id,
+                               'id_services' => $this->service_id
+                           );
+        $validation_result = $this->CI->Appointments_Model->validate_data($appointment_data);
+        $this->CI->unit->run($validation_result, TRUE, 'Test validate_data() method.');
+    }
+    
+    private function test_validate_data_wrong_date_format() {
+        $appointment_data = array(
+                               'start_datetime' => '20WRONG13-05-01 12WRONG:30:00',
+                               'end_datetime' => '2013-05WRONG-01 13:00WRONG:00',
+                               'notes' => 'Some notes right here...',
+                               'id_users_provider' => $this->provider_id,
+                               'id_users_customer' => $this->customer_id,
+                               'id_services' => $this->service_id
+                           );
+        $validation_result = $this->CI->Appointments_Model->validate_data($appointment_data);
+        $this->CI->unit->run($validation_result, FALSE, 'Test validate_data() method with wrong date formats.');
+    }
+    
+    private function test_validate_data_invalid_provider_id() {
+        $appointment_data = array(
+                               'start_datetime' => '2013-05-01 12:30:00',
+                               'end_datetime' => '2013-05-01 13:00:00',
+                               'notes' => 'Some notes right here...',
+                               'id_users_provider' => 'THIS IS WRONG',
+                               'id_users_customer' => $this->customer_id,
+                               'id_services' => $this->service_id
+                           );
+        $validation_result = $this->CI->Appointments_Model->validate_data($appointment_data);
+        $this->CI->unit->run($validation_result, FALSE, 'Test validate_data() method with invalid provider id.');
+    }
+    
+    private function test_validate_data_invalid_customer_id() {
+        $appointment_data = array(
+                               'start_datetime' => '2013-05-01 12:30:00',
+                               'end_datetime' => '2013-05-01 13:00:00',
+                               'notes' => 'Some notes right here...',
+                               'id_users_provider' => $this->provider_id,
+                               'id_users_customer' => 'THIS IS WRONG',
+                               'id_services' => $this->service_id
+                           );
+        $validation_result = $this->CI->Appointments_Model->validate_data($appointment_data);
+        $this->CI->unit->run($validation_result, FALSE, 'Test validate_data() method with invalid customer id.');
+    }
+    
+    private function test_validate_data_invalid_service_id() {
+        $appointment_data = array(
+                               'start_datetime' => '2013-05-01 12:30:00',
+                               'end_datetime' => '2013-05-01 13:00:00',
+                               'notes' => 'Some notes right here...',
+                               'id_users_provider' => $this->provider_id,
+                               'id_users_customer' => $this->customer_id,
+                               'id_services' => 'THIS IS WRONG'
+                           );
+        $validation_result = $this->CI->Appointments_Model->validate_data($appointment_data);
+        $this->CI->unit->run($validation_result, FALSE, 'Test validate_data() method with invalid service id.');
+    }
+}
+
+/* End of file Unit_tests_appointments_model.php */
+/* Location: ./application/libraries/Unit_tests/drivers/Unit_tests_appointments_model.php */
\ No newline at end of file
diff --git a/src/application/libraries/Unit_tests/drivers/Unit_tests_customers_model.php b/src/application/libraries/Unit_tests/drivers/Unit_tests_customers_model.php
new file mode 100644
index 00000000..dcb7a1d5
--- /dev/null
+++ b/src/application/libraries/Unit_tests/drivers/Unit_tests_customers_model.php
@@ -0,0 +1,39 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');  
+
+class Unit_tests_customers_model extends CI_Driver {
+    private $CI;
+    
+    public function __construct() {
+        $this->CI =& get_instance();
+        $this->CI->load->library('Unit_test');
+        $this->CI->load->model('Customers_Model');
+    }
+    
+    /**
+     * Run all the available tests
+     */
+    public function run_all() {
+        // All the methods whose names start with "test" are going to be 
+        // executed. If you want a method to not be executed remove the 
+        // "test" keyword from the beginning.
+        $class_methods = get_class_methods('Unit_tests_customers_model');
+        foreach ($class_methods as $method_name) {
+            if (substr($method_name, 0, 5) === 'test_') {
+                call_user_func(array($this, $method_name));
+            }
+        }
+    }
+    
+    /////////////////////////////////////////////////////////////////////////
+    // UNIT TESTS
+    /////////////////////////////////////////////////////////////////////////   
+    private function test_true() {
+        $this->CI->unit->run(TRUE, TRUE, 'True!');
+    }
+    
+    
+    
+}
+
+/* End of file Unit_tests_customers_model.php */
+/* Location: ./application/libraries/Unit_tests/drivers/Unit_tests_customers_model.php */
\ No newline at end of file
diff --git a/src/application/models/appointments_model.php b/src/application/models/appointments_model.php
index fe82de27..988e8123 100644
--- a/src/application/models/appointments_model.php
+++ b/src/application/models/appointments_model.php
@@ -6,7 +6,6 @@ class Appointments_Model extends CI_Model {
      */
     public function __construct() {
         parent::__construct();
-        $this->load->helper('custom_exceptions');
     }
     
     /**
@@ -97,7 +96,7 @@ class Appointments_Model extends CI_Model {
             throw new DatabaseException('Could not update appointment record.');
         }
         
-        return $appointment_data['id'];
+        return intval($appointment_data['id']);
     }
     
     /**
@@ -107,6 +106,9 @@ class Appointments_Model extends CI_Model {
      * get the unique id from the database: start_datetime, end_datetime, 
      * id_users_provider, id_users_customer, id_services.
      * 
+     * <strong>IMPORTANT!</strong> The record must already exists in the 
+     * database, otherwise an exception is raised.
+     * 
      * @expectedException DatabaseException
      * 
      * @param array $appointment_data Array with the appointment data. The 
@@ -136,7 +138,7 @@ class Appointments_Model extends CI_Model {
      * update operation is executed.
      * 
      * @param array $appointment_data Contains the appointment data.
-     * @return boolean Returns the validation result.
+     * @return bool Returns the validation result.
      */
     public function validate_data($appointment_data) {
         $this->load->helper('data_validation');
@@ -151,7 +153,35 @@ class Appointments_Model extends CI_Model {
                 throw new Exception('Appointment end datetime is invalid.');
             }
 
-            // @task Check if appointment foreign keys are valid.
+            // Check if the provider's id is valid. 
+            $num_rows = $this->db
+                                ->select('*')
+                                ->from('ea_users')
+                                ->join('ea_roles', 'ea_roles.id = ea_users.id_roles', 'inner')
+                                ->where('ea_users.id', $appointment_data['id_users_provider'])
+                                ->where('ea_roles.slug', DB_SLUG_PROVIDER)
+                                ->get()->num_rows();
+            if ($num_rows == 0) {
+                throw new Exception('Appointment provider id is invalid.');
+            }
+            
+            // Check if the customer's id is valid.
+            $num_rows = $this->db
+                                ->select('*')
+                                ->from('ea_users')
+                                ->join('ea_roles', 'ea_roles.id = ea_users.id_roles', 'inner')
+                                ->where('ea_users.id', $appointment_data['id_users_customer'])
+                                ->where('ea_roles.slug', DB_SLUG_CUSTOMER)
+                                ->get()->num_rows();
+            if ($num_rows == 0) {
+                throw new Exception('Appointment customer id is invalid.');
+            }
+            
+            // Check if the service id is valid.
+            $num_rows = $this->db->get_where('ea_services', array('id' => $appointment_data['id_services']))->num_rows();
+            if ($num_rows == 0) {
+                throw new Exception('Appointment customer id is invalid.');
+            }
             
             return TRUE;
         } catch (Exception $exc) {
@@ -166,6 +196,16 @@ class Appointments_Model extends CI_Model {
      * @return bool Returns the delete operation result.
      */
     public function delete($appointment_id) {
+        if (!is_int($appointment_id)) { 
+            return FALSE; // Invalid parameter given.
+        }
+        
+        $num_rows = $this->db->get_where('ea_appointments', array('id' => $appointment_id))->num_rows();
+        
+        if ($num_rows == 0) {
+            return FALSE; // Record does not exist.
+        }
+        
         $this->db->where('id', $appointment_id);
         return $this->db->delete('ea_appointments');
     }
@@ -179,6 +219,9 @@ class Appointments_Model extends CI_Model {
      * field names.
      */
     public function get_row($appointment_id) {
+        if (!is_int($appointment_id)) {
+            throw new DatabaseException('Invalid argument given. Expected integer for the $appointment_id.');
+        }
         return $this->db->get_where('ea_appointments', array('id' => $appointment_id))->row_array();
     }
     
@@ -191,7 +234,25 @@ class Appointments_Model extends CI_Model {
      * @return string Returns the records value from the database.
      */
     public function get_value($field_name, $appointment_id) {
-        return $this->db->get_where('ea_appointments', array('id' => $appointment_id))->row_array()[$field_name];
+        if (!is_int($appointment_id)) {
+            throw new DatabaseException('Invalid argument given, expected integer for the $appointment_id.');
+        }
+        
+        if (!is_string($field_name)) {
+            throw new DatabaseException('Invalid argument given, expected string for the $field_name.');
+        }
+        
+        if ($this->db->get_where('ea_appointments', array('id' => $appointment_id))->num_rows() == 0) {
+            throw new DatabaseException('The record with the provided id does not exist in the datbase.');
+        }
+        
+        $row_data = $this->db->get_where('ea_appointments', array('id' => $appointment_id))->row_array();
+        
+        if (!isset($row_data[$field_name])) {
+            throw new DatabaseException('The given field name does not exist in the database.');
+        }
+        
+        return $row_data[$field_name];
     }
     
     /**
diff --git a/test/AppointmentsModelTest.php b/test/AppointmentsModelTest.php
deleted file mode 100644
index 4ccc0c37..00000000
--- a/test/AppointmentsModelTest.php
+++ /dev/null
@@ -1,132 +0,0 @@
-<?php
-class AppointmentsModelTest extends PHPUnit_Framework_TestCase {
-    private $CI;
-    private $id_users_provider;
-    private $id_users_customer;
-    private $id_services;
-
-    public function setUp() {
-        $this->CI =& get_instance();
-        $this->CI->load->model('Appointments_Model'); // This model will be used in all test methods.
-        
-        $this->CI->load->model('Providers_Model');
-        $providers = $this->Providers_Model->get_row(2);
-//        if (count($providers) > 0) {
-//            $this->id_users_provider = $providers[0]['id'];
-//        } else {
-//            throw new Exception('There are no provider records ' 
-//                    . 'in the database. Add at least one provider '
-//                    . 'record before proceeding with the test.');
-//        }
-//        
-//        $this->CI->load->model('Customers_Model');
-//        $customers = $this->Customers_Model->get_batch();
-//        if (count($customers) > 0) {
-//            $this->id_users_customer = $customers[0]['id'];
-//        } else {
-//            throw new Exception('There are no customer records ' 
-//                    . 'in the database. Add at least one customer '
-//                    . 'record before proceeding with the test.');
-//        }
-//        
-//        $this->CI->load->model('Services_Model');
-//        $services = $this->Services_Model->get_batch();
-//        if (count($services) > 0) {
-//            $this->id_services = $services[0]['id'];
-//        } else {
-//            throw new Exception('There are no customer records ' 
-//                    . 'in the database. Add at least one customer '
-//                    . 'record before proceeding with the test.');
-//        }
-    }
-    
-    public function test_sample() {
-        //$this->assertEquals(1,1);
-    }
-    
-    /////////////////////////////////////////////////////////////////////////////////
-    // ADD RECORD METHOD TESTS 
-    /////////////////////////////////////////////////////////////////////////////////
-//    public function test_add_appointment_insert() {
-//        // To trigger the insert method no record id needs to be 
-//        // provided.
-//        $appointment_data = array(
-//                                'start_datetime' => '2013-05-01 12:30:00',
-//                                'end_datetime' => '2013-05-01 13:00:00',
-//                                'notes' => 'Some notes right here...',
-//                                'id_users_provider' => $this->id_users_provider,
-//                                'id_users_customer' => $this->id_users_customer,
-//                                'id_services' => $this->id_services
-//                            );
-//        
-//        $appointment_id = $this->Appointments_Model->add($appointment_data);
-//        
-//        // Check if the record is the one that was inserted.
-//        $db_data = $this->Appointments_Model->get_row($appointment_id);
-//        
-//        $this->assertEquals($appointment_data['start_datetime'], $db_data['start_datetime']);
-//        $this->assertEquals($appointment_data['end_datetime'], $db_data['end_datetime']);
-//        $this->assertEquals($appointment_data['notes'], $db_data['notes']);
-//        $this->assertEquals($appointment_data['id_users_provider'], $db_data['id_users_provider']);
-//        $this->assertEquals($appointment_data['id_users_customer'], $db_data['id_users_customer']);
-//        $this->assertEquals($appointment_data['id_services'], $db_data['id_services']);
-//        
-//        // Delete inserted record.
-//        $this->Appointments_Model->delete($appointment_id);
-//    }
-//    
-//    public function test_add_appointment_update() {
-//        // Insert new record.
-//        $appointment_data = array(
-//                                'start_datetime' => '2013-05-01 12:30:00',
-//                                'end_datetime' => '2013-05-01 13:00:00',
-//                                'notes' => 'Some notes right here...',
-//                                'id_users_provider' => $this->id_users_provider,
-//                                'id_users_customer' => $this->id_users_customer,
-//                                'id_services' => $this->id_services
-//                            );
-//        
-//        $appointment_id = $this->Appointments_Model->add($appointment_data);
-//        
-//        // Update new record.
-//        $new_notes_content = 'Some OTHER notes here ...';
-//        $appointment_data['notes'] = $new_notes_content;
-//        $this->Appointments_Model->add($appointment_data);
-//        
-//        // Check if the record was successfully updated.
-//        $db_data = $this->Appointments_Model->get_row($appointment_id);
-//        
-//        $this->assertEquals($appointment_data['start_datetime'], $db_data['start_datetime']);
-//        $this->assertEquals($appointment_data['end_datetime'], $db_data['end_datetime']);
-//        $this->assertEquals($appointment_data['notes'], $db_data['notes']);
-//        $this->assertEquals($appointment_data['id_users_provider'], $db_data['id_users_provider']);
-//        $this->assertEquals($appointment_data['id_users_customer'], $db_data['id_users_customer']);
-//        $this->assertEquals($appointment_data['id_services'], $db_data['id_services']);
-//        
-//        // Delete inserted record.
-//        $this->Appointments_Model->delete($appointment_id);
-//    }
-//    
-//    public function test_add_appointment_no_foreign_keys() {
-//    
-//        
-//    }
-//    
-//    /////////////////////////////////////////////////////////////////////////////////
-//    // RECORD EXISTS METHOD TESTS
-//    /////////////////////////////////////////////////////////////////////////////////
-//    public function test_exists_true() {
-//        
-//    }
-//    
-//    public function test_exists_false() {
-//        
-//    }
-//    
-//    public function test_exists_wrong_data() {
-//        
-//    }
-}
-    
-/* End of file appointments_modelTest.php */
-/* Location: ../test/appointments_modelTest.php */
\ No newline at end of file
diff --git a/test/bootstrap.php b/test/bootstrap.php
deleted file mode 100644
index 6f59dd91..00000000
--- a/test/bootstrap.php
+++ /dev/null
@@ -1,212 +0,0 @@
-<?php
-
-/*
- *---------------------------------------------------------------
- * APPLICATION ENVIRONMENT
- *---------------------------------------------------------------
- *
- * You can load different configurations depending on your
- * current environment. Setting the environment also influences
- * things like logging and error reporting.
- *
- * This can be set to anything, but default usage is:
- *
- *     development
- *     testing
- *     production
- *
- * NOTE: If you change these, also change the error_reporting() code below
- *
- */
-	define('ENVIRONMENT', 'testing');
-/*
- *---------------------------------------------------------------
- * ERROR REPORTING
- *---------------------------------------------------------------
- *
- * Different environments will require different levels of error reporting.
- * By default development will show errors but testing and live will hide them.
- */
-
-if (defined('ENVIRONMENT'))
-{
-	switch (ENVIRONMENT)
-	{
-		case 'development':
-			error_reporting(E_ALL);
-		break;
-	
-		case 'testing':
-		case 'production':
-			error_reporting(0);
-		break;
-
-		default:
-			exit('The application environment is not set correctly.');
-	}
-}
-
-/*
- *---------------------------------------------------------------
- * SYSTEM FOLDER NAME
- *---------------------------------------------------------------
- *
- * This variable must contain the name of your "system" folder.
- * Include the path if the folder is not in the same  directory
- * as this file.
- *
- */
-	$system_path = '../src/system';
-
-/*
- *---------------------------------------------------------------
- * APPLICATION FOLDER NAME
- *---------------------------------------------------------------
- *
- * If you want this front controller to use a different "application"
- * folder then the default one you can set its name here. The folder
- * can also be renamed or relocated anywhere on your server.  If
- * you do, use a full server path. For more info please see the user guide:
- * http://codeigniter.com/user_guide/general/managing_apps.html
- *
- * NO TRAILING SLASH!
- *
- */
-	$application_folder = '../src/application';
-
-/*
- * --------------------------------------------------------------------
- * DEFAULT CONTROLLER
- * --------------------------------------------------------------------
- *
- * Normally you will set your default controller in the routes.php file.
- * You can, however, force a custom routing by hard-coding a
- * specific controller class/function here.  For most applications, you
- * WILL NOT set your routing here, but it's an option for those
- * special instances where you might want to override the standard
- * routing in a specific front controller that shares a common CI installation.
- *
- * IMPORTANT:  If you set the routing here, NO OTHER controller will be
- * callable. In essence, this preference limits your application to ONE
- * specific controller.  Leave the function name blank if you need
- * to call functions dynamically via the URI.
- *
- * Un-comment the $routing array below to use this feature
- *
- */
-	// The directory name, relative to the "controllers" folder.  Leave blank
-	// if your controller is not in a sub-folder within the "controllers" folder
-	// $routing['directory'] = '';
-
-	// The controller class file name.  Example:  Mycontroller
-	// $routing['controller'] = '';
-
-	// The controller function you wish to be called.
-	// $routing['function']	= '';
-
-
-/*
- * -------------------------------------------------------------------
- *  CUSTOM CONFIG VALUES
- * -------------------------------------------------------------------
- *
- * The $assign_to_config array below will be passed dynamically to the
- * config class when initialized. This allows you to set custom config
- * items or override any default config values found in the config.php file.
- * This can be handy as it permits you to share one application between
- * multiple front controller files, with each file containing different
- * config values.
- *
- * Un-comment the $assign_to_config array below to use this feature
- *
- */
-	// $assign_to_config['name_of_config_item'] = 'value of config item';
-    $assign_to_config['uri_protocol'] = 'PATH_INFO'; // This is needed to run tests on netbeans and code igniter.
-
-
-// --------------------------------------------------------------------
-// END OF USER CONFIGURABLE SETTINGS.  DO NOT EDIT BELOW THIS LINE
-// --------------------------------------------------------------------
-
-/*
- * ---------------------------------------------------------------
- *  Resolve the system path for increased reliability
- * ---------------------------------------------------------------
- */
-
-	// Set the current directory correctly for CLI requests
-	if (defined('STDIN'))
-	{
-		chdir(dirname(__FILE__));
-	}
-
-	if (realpath($system_path) !== FALSE)
-	{
-		$system_path = realpath($system_path).'/';
-	}
-
-	// ensure there's a trailing slash
-	$system_path = rtrim($system_path, '/').'/';
-
-	// Is the system path correct?
-	if ( ! is_dir($system_path))
-	{
-		exit("Your system folder path does not appear to be set correctly. Please open the following file and correct this: ".pathinfo(__FILE__, PATHINFO_BASENAME));
-	}
-
-/*
- * -------------------------------------------------------------------
- *  Now that we know the path, set the main path constants
- * -------------------------------------------------------------------
- */
-	// The name of THIS file
-	define('SELF', pathinfo(__FILE__, PATHINFO_BASENAME));
-
-	// The PHP file extension
-	// this global constant is deprecated.
-	define('EXT', '.php');
-
-	// Path to the system folder
-	define('BASEPATH', str_replace("\\", "/", $system_path));
-
-	// Path to the front controller (this file)
-	define('FCPATH', str_replace(SELF, '', __FILE__));
-
-	// Name of the "system folder"
-	define('SYSDIR', trim(strrchr(trim(BASEPATH, '/'), '/'), '/'));
-
-
-	// The path to the "application" folder
-	if (is_dir($application_folder))
-	{
-		define('APPPATH', $application_folder.'/');
-	}
-	else
-	{
-		if ( ! is_dir(BASEPATH.$application_folder.'/'))
-		{
-			exit("Your application folder path does not appear to be set correctly. Please open the following file and correct this: ".SELF);
-		}
-
-		define('APPPATH', BASEPATH.$application_folder.'/');
-	}
-        
-/**
- * --------------------------------------------------------------------
- * CHECK IF EASY!APPOINTMENTS IS INSTALLED AND CONFIGURED
- * --------------------------------------------------------------------
- */        
-// If not show the installer instead of the main page.       
-
-/*
- * --------------------------------------------------------------------
- * LOAD THE BOOTSTRAP FILE
- * --------------------------------------------------------------------
- *
- * And away we go...
- *
- */
-require_once BASEPATH.'core/CodeIgniter.php';
-
-/* End of file index.php */
-/* Location: ./index.php */
\ No newline at end of file
diff --git a/test/phpunit.xml b/test/phpunit.xml
deleted file mode 100644
index a074d112..00000000
--- a/test/phpunit.xml
+++ /dev/null
@@ -1,10 +0,0 @@
-<phpunit bootstrap="bootstrap.php"
-    colors="true"
-    convertErrorsToExceptions="true"
-    convertNoticesToExceptions="true"
-    convertWarningsToExceptions="true"
-    processIsolation="true"
-    stopOnFailure="false"
-    syntaxCheck="true"
-    verbose="true">
-</phpunit>
\ No newline at end of file