Question

I’m new to programming, OOP and Unit Test so please forgive me for my lack of knowledge.

As part of my Rock, Paper and Scissors game I have a abstract superclass (Weapon) which has subclasses (Rock, Paper and Scissors) in VB.NET like:

    Public MustInherit Class Weapons
         Public MustOverride Function compareTo(ByVal Weapons As Object) As Integer

    End Class

    Public Class Paper
        Inherits Weapons

        Public Overrides Function compareTo(ByVal Weapons As Object) As Integer
            If TypeOf Weapons Is Paper Then
                Return 0
            ElseIf TypeOf Weapons Is Rock Then
                Return 1
            Else
                Return -1
            End If
        End Function
    End Class

    Public Class Rock
        Inherits Weapons

        Public Overrides Function compareTo(ByVal Weapons As Object) As Integer
            If TypeOf Weapons Is Rock Then
                Return 0
            ElseIf TypeOf Weapons Is Scissors Then
                Return 1
            Else
                Return -1
            End If
        End Function
    End Class

    Public Class Scissors
        Inherits Weapons

        Public Overrides Function compareTo(ByVal Weapons As Object) As Integer
            If TypeOf Weapons Is Scissors Then
                Return 0
            ElseIf TypeOf Weapons Is Paper Then
                Return 1
            Else
                Return -1
            End If
        End Function
    End Class

Also have a superclass Player which has subclasses (PlayerComputerRandom, PlayerHumanPlayer and PlayerComputerTactical) like:

    Imports RockPaperScissors.Weapons

Public Class Player

    Private pName As String
    Private pNumberOfGamesWon As String
    Public pWeapon As Weapons

    Property Name() As String
        Get
            Return pName
        End Get
        Set(ByVal value As String)
            pName = value
        End Set
    End Property

    Property NumberOfGamesWon As String
        Get
            Return pNumberOfGamesWon
        End Get
        Set(ByVal value As String)
            pNumberOfGamesWon = value
        End Set
    End Property

    Property getWeapon As Weapons
        Get
            Return pWeapon
        End Get
        Set(ByVal value As Weapons)
            pWeapon = value
        End Set
    End Property

    Public Sub pickWeapon(ByVal WeaponType As String)
        If WeaponType = "Rock" Then
            pWeapon = New Rock()

        ElseIf WeaponType = "Paper" Then
            pWeapon = New Paper()

        Else
            pWeapon = New Scissors()

        End If

    End Sub

End Class



    Imports RockPaperScissors.Weapons

Public Class PlayerComputerRandom
    Inherits Player

    Private Enum weaponsList
        Rock
        Paper
        Scissors
    End Enum

    Public Overloads Sub pickWeapon()

        Dim randomChoice = New Random()
        Dim CompChoice As Integer = randomChoice.Next(0, [Enum].GetValues(GetType(weaponsList)).Length)

        If CompChoice = "0" Then
            pWeapon = New Rock()

        ElseIf CompChoice = "1" Then
            pWeapon = New Paper()

        Else
            pWeapon = New Scissors()

        End If


    End Sub

End Class



 Public Class PlayerComputerTactical
    Inherits Player

    Private plastMove As String

    Property lastMove() As String
        Get
            Return plastMove
        End Get
        Set(ByVal value As String)
            plastMove = value
        End Set
    End Property

    Public Overloads Sub pickWeapon()
        ' Add tactical player functionality
    End Sub


End Class


     Public Class PlayerHumanPlayer
        Inherits Player

    End Class

I have the GameForm class which instantiates the objects and performs various other logic used for the front-end as shown below:

    Public Class GameForm
    Private Sub btnRock_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRock.Click
        findWinner("HumanPlayer", "Rock", "RandomComputer")
    End Sub

    Private Sub btnPaper_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPaper.Click
        findWinner("HumanPlayer", "Paper", "RandomComputer")
    End Sub


    Private Sub btnScissors_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnScissors.Click
        findWinner("HumanPlayer", "Scissors", "RandomComputer")
    End Sub

    Public Sub findWinner(ByVal p1name As String, ByVal p1WeaponSelected As String, ByVal p2Name As String)
        Dim player1 = New PlayerHumanPlayer()
        Dim player2 = New PlayerComputerRandom()

        player1.Name = p1name
        player1.pickWeapon(p1WeaponSelected)  ' Should I be using the Rock Class???

        player2.Name = p2Name
        player2.pickWeapon()

        Dim winner As Integer = player1.getWeapon().compareTo(player2.getWeapon())

        Select Case winner
            Case 1
                txtGameStatus.Text = player1.Name() + " wins!"
            Case -1
                txtGameStatus.Text = player2.Name() + " wins!"
            Case 0
                txtGameStatus.Text = "Draw!"
        End Select
    End Sub

End Class

I need to write unit tests of this using visual studio 2010. As I have never done this, I don’t know what unit tests I could include (apart from the stand adding/substract examples). Could someone kindly provide a few unit tests to get started. It will give me a starting point.

Any help would be greatly appreciated.

Manys thanks in advance

Answer 1

To try to give you an example of how you might structure this:

First of all, instead of this:

Public Overloads Sub pickWeapon()
   ' Logic...         
End Sub

You might want to do something like this:

 Public Overloads Function pickWeapon() as Weapons

    Dim selectedWeapon as Weapons = Nothing;

    // logic to set weapon here

    return selectedWeapon;
End Sub

Now you can call that from a UnitTest, and make sure it returns an object which is a valid Weapon, for instance (not necessarily the most useful test, but hopefully, you get the point! 🙂 ).

If your restructure the method findWinner() in a similar way, you can test that the logic of that method finds the correct winner.

Note however, that you should separate the logic for finding a winner from the weapon-picking. That is, you should create the players outside of that method, and pass them in to findWinner(). This will let you pass in certain options (weapons), and check that you get the expected result. You can’t do that at the moment, since the weapon “player2” will use is selected by random inside findWinner().

Start by changing it so it will have a signature similar to the following:

' Takes two players in, and returns the name of the winner
Public Sub findWinner(ByVal humanPlayer As PlayerHumanPlayer, 
                      ByVal computerPlayer As PlayerComputerRandom) As String

A (very simple) test, assuming you’ve rewritten the code to fit this:

<TestMethod()> _
Public Sub ShouldReturnPlayer1AsWinner()

    Dim player1 = New PlayerHumanPlayer("Human name", New Scissors())
    Dim player2 = New PlayerComputerRandom("Computer", New Rock())

    Dim result As String = findWinner(player1, player2)

    Assert.AreEqual(result, "Computer")

End Sub

Again, this may not be the be the best test, but it should give you an idea, and help you get started.

Sidenote: I would call the super-class Weapon, not Weapons. Think of it this way: You can have many many different instances of it, and they can be different weapons (paper, scissor, etc), but each is still a single weapon.