paired <- function() {
  set.seed(1)
  d <- do.call(rbind, lapply(c("T1", "T2"), function(s)
    data.frame(sim = s, Date = as.Date("2001-10-31") + (0:7) * 365,
               variable = "wrr", obs = seq(5000, 9000, length.out = 8),
               stringsAsFactors = FALSE)))
  d$pred <- d$obs * runif(nrow(d), 0.9, 1.1)
  d
}

test_that("stats_by = character(0) pools even when points are coloured", {
  p <- plot_one2one(paired(), group = "sim", stats_by = character(0))
  lab <- Filter(function(x) inherits(x$geom, "GeomText"), p$layers)[[1]]$data$lab
  expect_length(lab, 1L)
  expect_true(grepl("n = 16", lab))
})

test_that("stats_by splits the corner box when asked", {
  p <- plot_one2one(paired(), group = "sim", stats_by = "sim", facet = "sim")
  lab <- Filter(function(x) inherits(x$geom, "GeomText"), p$layers)[[1]]$data$lab
  expect_length(lab, 2L)
  expect_true(all(grepl("n = 8", lab)))
})

test_that("a faceted plot gets one box per panel, never a repeated pooled box", {
  d <- paired()
  d$phase <- factor(rep(c("Calibration", "Validation"), each = 8))
  p <- plot_one2one(d, facet = "phase", stats_by = c("phase", "sim"))
  lab <- Filter(function(x) inherits(x$geom, "GeomText"), p$layers)[[1]]$data
  expect_equal(nrow(lab), 2L)
  expect_equal(sort(as.character(lab$phase)), c("Calibration", "Validation"))
})

test_that("the corner box agrees with gof() for the same grouping", {
  d <- paired()
  p <- plot_one2one(d, stats_by = character(0), stats = c("n", "rmse"))
  lab <- Filter(function(x) inherits(x$geom, "GeomText"), p$layers)[[1]]$data$lab
  g <- gof("obs", "pred", data = d)
  expect_true(grepl(sprintf("RMSE = %.2f", g$rmse), lab, fixed = TRUE))
})