shinyjster test for Date range picker functionality

[MadhulikaTanuboddi]

Add a shinyjster test for the following shiny app

## Only run examples in interactive R sessions
if (interactive()) {

  ui <- fluidPage(
    sliderInput("n", "Day of month", 1, 30, 10),
    dateRangeInput("inDateRange", "Input date range")
  )

  server <- function(input, output, session) {
    observe({
      date <- as.Date(paste0("2013-05-", input$n))

      updateDateRangeInput(session, "inDateRange",
                           label = paste("Date range label", input$n),
                           start = date - 1,
                           end = date + 1,
                           min = date - 5,
                           max = date + 5
      )
    })
  }

  shinyApp(ui, server)
}