Using serial.print to debug a library

Using Arduino Programming Questions
8

So just to recap I seem to be having linker errors for this example to use the Serial.print function from a library as coded in multiple tabs in a sketch:
.ino file

#include "MyLibrary.h"

MyLibrary myLibrary(Serial);

void setup() {

  myLibrary.test();
}
void loop() {}

.cpp file

#include "HardwareSerial.h"

class MyLibrary {
  public:
    //pass a reference to a Print object
    MyLibrary( HardwareSerial &print ) { 
      printer = &print; //operate on the address of print
      printer->begin(9600);
    }
    void test() {
      printer->println("Hello library with serial connectivity!");
    }
  private:
    HardwareSerial* printer;
};

.h file

#ifndef _EXAMPLE_SPLIT_H
#define _EXAMPLE_SPLIT_H
#endif
#if defined(ARDUINO) && ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif

class MyLibrary {
  public:
    //pass a reference to a Print object
    MyLibrary( HardwareSerial &print );
    void test();
  private:
    HardwareSerial* printer;
};

Errors:

HardwareSerialClassExampleSplit.cpp.o: In function __static_initialization_and_destruction_0': C:\Users\Kb\AppData\Local\Temp\build5255053454461430477.tmp/HardwareSerialClassExampleSplit.cpp:7: undefined reference to MyLibrary::MyLibrary(HardwareSerial&)'
HardwareSerialClassExampleSplit.cpp.o: In function setup': C:\Users\Kb\AppData\Local\Temp\build5255053454461430477.tmp/HardwareSerialClassExampleSplit.cpp:11: undefined reference to MyLibrary::test()'

Thanks in advance for advice on how to resolve this or if this is not allowed for some reason.

Cheers Kb