Indexing a variable twice in R shiny - r

Question

I'm trying to do some integration testing on my Shiny app, but I don't know what I'm doing wrong. I suspect it has to do with the fact I used the "$" twice when trying to access the likelihood, color, and riskMessage variables.
I keep running into this error:
Error in checkEqualsNumeric(output$coloredBox$likelihoodOfHarm, 0.75) :
Modes: NULL, numeric
Lengths: 0, 1
target is NULL, current is numeric
Here is my Shiny app code, with my attempt to test the Shiny app at the bottom. Any help is greatly appreciated!
displayColoredBox<- function(color, riskMessage){
sidebarPanel(style=sprintf("background-color: %s; width: 300px; height: 300px;", color),
h3(sprintf("%s", riskMessage)) ) }
app <- shinyApp(
ui = fluidPage(
div(
id = "form",
sliderInput("count1", "First Slider Input", value=0, min=0, max=5000),
sliderInput("count2", "Second Slider Input", value=0, min=0, max=5000),
uiOutput("coloredBox")
)),
server <- function(input, output, session) {
output$coloredBox<-renderUI({
req(input$count1)
req(input$count2)
count1 <- input$count1;
count2 <- input$count2;
likelihood <- (count1*count2)/5000000
if (likelihood>1) {
color="red"
riskMessage="Extreme risk!"
} else if (likelihood>.65){
color="orange"
riskMessage="Very high risk!"
}
else if (likelihood>.35){
color="yellow"
riskMessage="High risk!"
}
else if (likelihood>.10){
color="blue"
riskMessage="Moderate risk!"
} else {
color="green"
riskMessage="Low risk!"
}
coloredBox=displayColoredBox(color, riskMessage)
})
}
)
testServer(app, {
session$setInputs(count1 = 1500)
session$setInputs(count2 = 2500)
checkEqualsNumeric(output$coloredBox$likelihood, 0.75)
checkEquals(output$coloredBox$riskMessage, "Very high risk!")
checkEquals(output$coloredBox$color, "orange")
})

Answer 1

output objects in Shiny Apps are not lists that you can access in the way you are trying to. In contrast, they are HTML objects. The shiny-way would be the following: Store your values as reactives that change according to the inputs. Check if the reactives have the desired values.
displayColoredBox<- function(color, riskMessage){
sidebarPanel(style=sprintf("background-color: %s; width: 300px; height: 300px;", color),
h3(sprintf("%s", riskMessage)) ) }
library(RUnit)
app <- shinyApp(
ui = fluidPage(
div(
id = "form",
sliderInput("count1", "First Slider Input", value=0, min=0, max=5000),
sliderInput("count2", "Second Slider Input", value=0, min=0, max=5000),
uiOutput("coloredBox")
)),
server <- function(input, output, session) {
likelihood <- reactive((input$count1*input$count2)/5000000)
boxValues <- reactiveValues(color="", riskMessage="")
observe({
req(input$count1)
req(input$count2)
if (likelihood()>1) {
boxValues$color="red"
boxValues$riskMessage="Extreme risk!"
} else if (likelihood()>.65){
boxValues$color="orange"
boxValues$riskMessage="Very high risk!"
}
else if (likelihood()>.35){
boxValues$color="yellow"
boxValues$riskMessage="High risk!"
}
else if (likelihood()>.10){
boxValues$color="blue"
boxValues$riskMessage="Moderate risk!"
} else {
boxValues$color="green"
boxValues$riskMessage="Low risk!"
}
})
output$coloredBox<-renderUI({
displayColoredBox(boxValues$color, boxValues$riskMessage)
})
}
)
testServer(app, {
session$setInputs(count1 = 1500)
session$setInputs(count2 = 2500)
checkEquals(likelihood(), 0.75)
checkEquals(boxValues$riskMessage, "Very high risk!")
checkEquals(boxValues$color, "orange")
})