Why is this an issue?
An operand of a boolean expression that never changes the result of the expression might not match the programmer’s intent and can lead to
unexpected behavior and potential bugs.
Dim a = True
If a Then
DoSomething()
End If
This also applies to the null conditional operator
when one of the operands always evaluates to Nothing.
Dim d As String = Nothing
Dim v1 = If(d, "value")
Exceptions
This rule will not raise an issue in either of these cases:
- When the condition is a single
Const bool
Const debug = False
'...
If debug Then
' Print something
End If
- When the condition is the literal
True or False.
In these cases, it is obvious the code is as intended.
How to fix it
The conditions should be reviewed to decide whether:
- to update the unnecessary operand
- to remove the unnecessary operand
Code examples
Noncompliant code example
Public Sub Sample(ByVal b As Boolean, ByVal c As Boolean)
Dim a = True
If a Then ' Noncompliant: "a" is always "true"
DoSomething()
End If
If b AndAlso a Then ' Noncompliant: "a" is always "true"
DoSomething()
End If
If c OrElse Not a Then ' Noncompliant: "Not a" is always "false"
DoSomething()
End If
Dim d As String = Nothing
Dim v1 = If(d, "value") ' Noncompliant: "d" is always Nothing and v1 is always "value".
Dim v2 = If(s, d) ' Noncompliant: "d" is always Nothing and v2 is always equal to s.
End Sub
Compliant solution
Public Sub Sample(ByVal b As Boolean, ByVal c As Boolean, ByVal s As String)
Dim a = IsAllowed()
If a Then ' Compliant
DoSomething()
End If
If b AndAlso a Then ' Compliant
DoSomething()
End If
If c OrElse Not a Then ' Compliant
DoSomething()
End If
Dim d As String = GetStringData()
Dim v1 = If(d, "value") ' Compliant
Dim v2 = If(s, d) ' Compliant
End Sub
Resources
Documentation
