Mock models with PHPUnit

I have found one resolution that is described after my question. I was wondering if you could point me in the direction on where I can find some reading material regarding unit testing, I am interested in:
- Use of fake classes in PHPUnit for testing?
- Working with a dummy database to test application ( Live application )?
- Creation of dummy data for unit testing using arrays?


Question:

I have a library with a range of functions, some of the functions send data to the model to perform CRUD operations.

At the present moment I am interested in creating a dummy set of data and a mock of those CRUD operations, so rather than going into DB i would get data from a dummy set of data.

I have found some examples online on how to do Mock of the function but i didn't have much luck getting Mock to work, my original function still communicates to the DB.

Below is example of the code that I have in my PHPUnit test class

PHP Code:

public function testSaveExistingSupplier()
{
        $suppliers = array(
            array('id' => '1', 'name' => 'O2')
        );
        // Create a stub.
        require_once(APPPATH . '/models/suppliers_model.php');
        $stub = $this->getMockBuilder('suppliers_model')
                ->getMock(); 

        // Configure the stub.
        $stub->expects($this->any())
             ->method('getSupplierByText')
             ->will($this->returnValueMap($suppliers));
        
        $result = $this->ci->suppliers->saveSupplier("O2");
        $this->assertEquals($result, $suppliers[0]['id'], "Supplier exists");
} 


saveSupplier functions checks in DB if supplier with supplied param exists (in our case "O2") by calling getSupplierByText method in suppliers_model. If supplier exists than we return int other ways we create new supplier and return int.

So, I have tried to create a mock function that changes the return value for method getSupplierByText

-------------

Current Resolution:
I have also tried implementation below, taken from the PHPUnit 3.7 DOC:

PHP Code:

$suppliers = array('id' => '1', 'name' => 'O2');
// Create a stub for the SomeClass class.
$stub = $this->getMock('suppliers_model'); 

// Configure the stub.
$stub->expects($this->any())
     ->method('getSupplierByText')
     ->will($this->returnValue($suppliers));

$result = $stub->saveSupplier("O2");
$this->assertEquals($result, $suppliers[0]['id'], "Existing supplier exists"); 


The code above code works, I had to create a new function in my library that dealt with a call to the model; below is my original function:

PHP Code:

public function saveSupplier($supplier)
{
    // find if this supplier exists
    $supplier_info = $this->ci->suppliers_model->getSupplierByText($supplier);

    if($supplier_info != FALSE)
    {
        // supplier already exists
        return $supplier_info[0]['id'];
    }

    // create new supplier
    $options = array();
    $options['text'] = $supplier;

    $supplier_id = $this->ci->suppliers_model->createEntry($options);

    return $supplier_id;
} 


On the 4th line I have amended the code to "$supplier_info = $this->getSupplierByText($supplier);" and created a new function that deals with a call:

PHP Code:

public function getSupplierByText($supplier)
    {
        return $this->ci->expense_suppliers->getSupplierByText($supplier);
    } 


Now, because I am calling a specific function within a library that I am testing , I was able to mask "getSupplierByText" function and provide a desired return parameter.