Controlling PInvoke Methods

When to Use

When your test requires a pinvoke method to return a specific value.

Syntax

C#

Isolate.WhenCalled(() => <pInvoke-method()>).<behavior>;

VB

Isolate.WhenCalled(Function() <pInvoke-method()>).<behavior>

Samples

C#
 
[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool Beep(uint dwFreq, uint dwDuration);

[TestMethod]
public void PInvokeMethod_Example()
{
  Isolate.WhenCalled(()=> Beep(0,0)).WillReturn(false);
 
  var result = Beep(100, 200);
  Assert.AreEqual(false, result);
}

VB

<DllImport("kernel32.dll", SetLastError:=True)>
    Private Shared Function Beep(dwFreq As UInteger, dwDuration As UInteger) As <MarshalAs(UnmanagedType.Bool)> Boolean
End Function

<TestMethod(), Isolated()>
Public Sub PInvokeMethod_Example()
    Isolate.WhenCalled(Function() Beep(0, 0)).WillReturn(False)


    Dim result = Beep(100, 200)
    Assert.AreEqual(False, result)
End Sub