Source IP Allow to VS then URI Rewrite

Try this:

when HTTP_REQUEST { 
    log local0. "Incoming URI = [HTTP::uri]" 
    if {[class match [IP::client_addr] equals "IP_Allow_Data_Group"]} {
        if { [string tolower [HTTP::uri]] starts_with "/test" } { 
            set uri [string map -nocase {test dev} [HTTP::uri]]
            log local0. "New URI = $uri" 
            HTTP::uri $uri 
            SSL::disable serverside
            pool webtest-test.com-80 
        } 
    }
    else {
        HTTP::close
    }
}