library(pROC)
# works fine
controls <- c(1,2,3,4,5)
cases <- c(2,3,4,5,6)
roc_data <- roc(controls = controls,
                cases = cases,
                percent=TRUE, ci = TRUE, print.auc=TRUE)
plot(roc_data)

# runs fine if infinite value is in controls
controls <- c(1,2,3,4,5,Inf)
cases <- c(2,3,4,5,6)
roc_data <- roc(controls = controls,
                cases = cases,
                percent=TRUE, ci = TRUE, print.auc=TRUE)
plot(roc_data)

# fails with added infinite value in cases
controls <- c(1,2,3,4,5)
cases <- c(2,3,4,5,6,Inf)
roc_data <- roc(controls = controls,
                cases = cases,
                percent=TRUE, ci = TRUE, print.auc=TRUE)
plot(roc_data)