library(testthat)
library(nc)
library(data.table)
context("measure")
source(system.file("test_engines.R", package="nc", mustWork=TRUE), local=TRUE)

DT <- data.table(a_1=10, b_2=21, a_2=20)
test_engines("measure single value", {
  out <- melt(DT, measure.vars=nc::measure(
    letter="[ab]", "_", number="[12]", as.integer))
  expected <- data.table(
    letter=c("a","b","a"),
    number=as.integer(c(1,2,2)),
    value=c(10,21,20))
  expect_identical(out, expected)
})

test_engines("measure multiple values", {
  out <- melt(DT, measure.vars=nc::measure(
    column="[ab]", "_", number="[12]", as.integer))
  expected <- data.table(
    number=as.integer(c(1,2)),
    a=c(10,20),
    b=c(NA,21))
  expect_identical(out, expected)
})