The Test method is used to determine whether Set should be run. DSC invokes Test before Set. The Test method returns a Boolean value.

The Test method must perform the following tests to ascertain the state of this configuration item:

• When Ensure is present, fail if the value does not exist.
• When Ensure is present, fail if the value exists, but the description does not match the requested value.
• When Ensure is absent, fail if the value name exists.
• Otherwise, pass.

The following snippet implements these tests:

[Boolean] Test() {
    $key = Get-Item $this.Path
    if ($this.Ensure -eq 'Present') {
        if ($key.GetValueNames() -notcontains $this.valueName) {
            return $false
        }
        return $key.GetValue($this.valueName) -eq $this.Description
    } else {
        return $key.GetValueNames() -notcontains $this.valueName
    }
    return $true
}

Each of  these methods must be copied back into the resource class.