Przejdź do głównej zawartości

Practical Scrum Training (2) Basic functionality is ready

I completed what can be called a basic version of our family tree application. This is what the user can do with it:
  • add new people to the tree
  • print the tree in text mode
  • save the tree as png file
The program works from command line and can be started by typing:

$ python

Prerequisities: there must be pydot and graphviz installed on the system to run the program.

The files:
The program has some shortcomings, for example it requires one to put the IDs of parents while adding a child, but in general it works fine. It can create a png picture like this one below.

This version is the baseline for the trainees to start. The backlog from which to work on extending the application will be published in next post.


Popularne posty z tego bloga

Unit Testing code with IO file operations (in Python)

We may often come across a piece of code that was written without Unit Tests at all. In addition, the piece of code may be dealing with IO like file writing and reading, which makes it more difficult to Unit Test it when we are trying to refactor and modify. Let's suppose the code in question looks like this:

def writeInitialsToFile(filename, name, surname):
    initials = name[0] + '.' + surname[0] + '.'
    with open(filename, 'w') as file:

def readInitials(filename):
    initials = None
    with open(filename, 'r') as file:
        initials = file.readline()
    return initials

A straightforward and bad idea would be to write a couple of Unit Tests that make use of a real file and simply test the reading and writing. Is therea a better way to test this code?

First of all, we need a way to replace the real file with something else. For both reading and writing we will now have a couple of functions, one that expects a stream fo…

Piotr's Less Obvious Advice on Google Mock: State maintenance

Google Mock provides several ways to maintain state inside mock objects. One way of implementing state maintenance is with SaveArg. Consider the following example.

We have a class Configurator, which allows a caller to set and get values of a parameter:

class Configurator

    virtual ~Configurator() {}

    virtual void setParamX(int n) = 0;
    virtual int getParamX() = 0;

And we have a class Client that calls Configurator's methods and it also has a method incParamXBy, that can be used to increase the current value of paramX by a certain value.

class Client

    Client(Configurator & cfg);
    virtual ~Client() {}

    void setParamX(int n);
    void incParamXBy(int n);
    int getParamX();


    Configurator & _cfg;

incParamXBy internally calls setParamX and getParamX on Configurator:

void Client::incParamXBy(int n)
    _cfg.setParamX(_cfg.getParamX() + n);

Let's assume that the initial value of paramX is A and that we want to increase paramX by…

Piotr's Less Obvious Advice on Google Mock: Returning new objects from a mock

Google Mock provides a way to return newly created objects from a mock method. Suppose we have a  Generator class that is supposed to generate new objects when createNewRecord method is called:

class Generator
    virtual ~Generator() {}
    virtual Record * createNewRecord() = 0;

...and suppose we want to mock this class:

class MockGenerator : public Generator
    MOCK_METHOD0(createNewRecord, Record * ());

Suppose the caller class Client has run method defined as follows:

void Client::run()
    for(int i = 0; i < 3; i++)
        rec_tab[i] = gen.createNewRecord();

We want the mock to return a pointer to a new object each time createNewRecord is called. This is how we can express this in the test code:

TEST(ClientTest, CanRun)
    MockGenerator gen;
    Client c(gen);

    EXPECT_CALL(gen, createNewRecord())
                 //this is equivalent of returning new Record(1,2,3)