BadDesign1.vb

Public Class BankAccount
    Public Sub New(AccountNumber As String)
        Me.AccountNumber = AccountNumber
    End Sub

    Public Property AccountNumber() As String
        Get
            Return m_AccountNumber
        End Get
        Private Set
            m_AccountNumber = Value
        End Set
    End Property
    Private m_AccountNumber As String
    Public Property AccountBalance() As Double
        Get
            Return m_AccountBalance
        End Get
        Set
            m_AccountBalance = Value
        End Set
    End Property
    Private m_AccountBalance As Double
    Public Property Interest() As Double
        Get
            Return m_Interest
        End Get
        Private Set
            m_Interest = Value
        End Set
    End Property
    Private m_Interest As Double
    Private Const InterestRate As Double = 5.5

    ' calculating interest business logic
    Public Sub CalculateInterest()
        Interest = (InterestRate * AccountBalance) / 100
    End Sub

    Public Sub SaveMoney(amount As Double)
        AccountBalance = AccountBalance + amount
    End Sub

    Public Sub WithdrawMoney(amount As Double)
        AccountBalance = AccountBalance - amount
    End Sub
  End Class

BadDesign2.vb

Public Class Shape
    Const CIRCLE As Integer = 1
    Const RECTANGLE As Integer = 2
    Private TYPE As Integer = 0

    Private radius As Double
    Private width As Double
    Private length As Double

    Public Function Area() As Double
        Select Case TYPE
            Case CIRCLE
                Return Math.PI * radius
            Case RECTANGLE
                Return width * length
            Case Else
                Return 0
        End Select
    End Function

    Public Sub CreateCircle(radius As Double)
        Me.radius = radius
        Me.TYPE = CIRCLE
    End Sub

    Public Sub CreateRectangle(length As Double, width As Double)
        Me.width = width
        Me.length = length
        Me.TYPE = RECTANGLE
    End Sub
End Class

BadDesign3.vb

Public Interface IShape
    Function Area() As Double
End Interface

Public Class Rectangle
    Implements IShape
    Public Property width() As Double
        Get
            Return m_width
        End Get
        Set
            m_width = Value
        End Set
    End Property
    Private m_width As Double
    Public Property length() As Double
        Get
            Return m_length
        End Get
        Set
            m_length = Value
        End Set
    End Property
    Private m_length As Double

    Private Sub New()
    End Sub

    Public Sub New(width As Double, length As Double)
        Me.width = width
        Me.length = length
    End Sub

    Public Function Area() As Double Implements IShape.Area
        Return Me.width * Me.length
    End Function
End Class

Public Class Square
    Inherits Rectangle

    Public Sub New(edge As Double)
        MyBase.New(edge, edge)
    End Sub

    Public Property edge() As Double
        Get
            Return m_edge
        End Get
        Set
            m_edge = Value
        End Set
    End Property
    Private m_edge As Double
End Class

BadDesign4.vb

Public Interface Vehicle
    Sub Fly()
    Sub Drive()
End Interface

Public Class Car
    Implements Vehicle

    Public Sub Drive() Implements Vehicle.Drive
        'Implement drive here
    End Sub

    Public Sub Fly() Implements Vehicle.Fly
        Throw New Exception("Can not fly")
    End Sub
End Class

Public Class Plane
    Implements Vehicle

    Public Sub Drive() Implements Vehicle.Drive
        Throw New Exception("Not a good idea")
    End Sub

    Public Sub Fly() Implements Vehicle.Fly
        'Implement fly here
    End Sub
End Class

BadDesign5.vb

Public Interface IOutputter
    Sub Print(output As String)
End Interface

Public Class ConsoleOutputter
    Implements IOutputter

    Public Sub Print(output As String) Implements IOutputter.Print
        System.Console.Write(output)
    End Sub
End Class

Public Class MockOutputter
    Implements IOutputter

    Public Sub Print(output As String) Implements IOutputter.Print
    End Sub
End Class

Public Class CommandInvoker
    Public Sub Invoke(outputter As ConsoleOutputter)
        outputter.Print("Hello World")
    End Sub
End Class