rspec/rules/S1479/vbnet/rule.adoc

== Why is this an issue?

When https://learn.microsoft.com/en-us/dotnet/visual-basic/language-reference/statements/select-case-statement[Select Case] statements have large sets of multi-line `Case` clauses, the code becomes hard to read and maintain.

For example, the https://www.sonarsource.com/docs/CognitiveComplexity.pdf[Cognitive Complexity] is going to be particularly high.

In such scenarios, it's better to refactor the `Select Case` to only have single-line case clauses.

When all the `Case` clauses of a `Select Case` statement are single-line, the readability of the code is not affected.

=== Exceptions

This rule ignores:

* `Select Case` statements over `Enum` arguments
* fall-through cases
* `Return` and `Throw` statements in `Case` clauses

== How to fix it

Extract the logic of multi-line `Case` clauses into separate methods.

=== Code examples

The examples below use the "Maximum number of case" property set to `4`.

==== Noncompliant code example

[source,vbnet,diff-id=1,diff-type=noncompliant]
----
Public Function MapChar(ch As Char, value As Integer) As Integer ' Noncompliant
    Select Case ch
        Case "a"c
            Return 1
        Case "b"c
            Return 2
        Case "c"c
            Return 3
        ' ...
        Case "-"c
            If value > 10 Then
                Return 42
            ElseIf value < 5 AndAlso value > 1 Then
                Return 21
            End If
            Return 99
        Case Else
            Return 1000
    End Select
End Function
----

==== Compliant solution

[source,vbnet,diff-id=1,diff-type=compliant]
----
Public Function MapChar(ch As Char, value As Integer) As Integer
    Select Case ch
        Case "a"c
            Return 1
        Case "b"c
            Return 2
        Case "c"c
            Return 3
        ' ...
        Case "-"c
            Return HandleDash(value)
        Case Else
            Return 1000
    End Select
End Function

Private Function HandleDash(value As Integer) As Integer
    If value > 10 Then
        Return 42
    ElseIf value < 5 AndAlso value > 1 Then
        Return 21
    End If
    Return 99
End Function
----

include::../resources-dotnet.adoc[]

* Microsoft Learn - https://learn.microsoft.com/en-us/dotnet/visual-basic/language-reference/statements/select-case-statement[Select...Case Statement]

include::../rspecator-dotnet.adoc[]