From c6c3e1d91784260c336c96c3a10ffc6787815a64 Mon Sep 17 00:00:00 2001
From: Utkarsh <utkarshpawadecse@gmail.com>
Date: Sat, 28 Mar 2026 16:47:59 +0530
Subject: [PATCH 1/6] Add dedicated edge-case tests for exported _data()
 functions

---
 .../testthat/test-data-functions-edge-cases.R | 505 ++++++++++++++++++
 1 file changed, 505 insertions(+)
 create mode 100644 tests/testthat/test-data-functions-edge-cases.R

diff --git a/tests/testthat/test-data-functions-edge-cases.R b/tests/testthat/test-data-functions-edge-cases.R
new file mode 100644
index 00000000..cce97fc2
--- /dev/null
+++ b/tests/testthat/test-data-functions-edge-cases.R
@@ -0,0 +1,505 @@
+source(test_path("data-for-ppc-tests.R"))
+load(test_path("data-for-ordinal.rda"))
+
+# ppc_bars_data edge cases -------------------------------------------------
+
+test_that("ppc_bars_data returns correct structure and types", {
+  d <- ppc_bars_data(y_ord, yrep_ord)
+  expect_s3_class(d, "data.frame")
+  expect_named(d, c("x", "y_obs", "l", "m", "h"))
+  expect_type(d$x, "double")
+  expect_type(d$y_obs, "integer")
+  expect_type(d$l, "double")
+  expect_type(d$m, "double")
+  expect_type(d$h, "double")
+})
+
+test_that("ppc_bars_data works with single observation", {
+  y1 <- 2L
+  yrep1 <- matrix(c(1L, 2L, 3L, 2L, 2L), ncol = 1)
+  d <- ppc_bars_data(y1, yrep1)
+  expect_s3_class(d, "data.frame")
+  expect_true(all(c("x", "y_obs") %in% names(d)))
+  expect_equal(d$y_obs[d$x == 2], 1)
+})
+
+test_that("ppc_bars_data works with single draw", {
+  y_single <- c(1L, 2L, 3L, 2L)
+  yrep_single <- matrix(c(1L, 2L, 2L, 3L), nrow = 1)
+  d <- ppc_bars_data(y_single, yrep_single)
+  expect_s3_class(d, "data.frame")
+  # with single draw, l == m == h
+  expect_equal(d$l, d$m, ignore_attr = TRUE)
+  expect_equal(d$m, d$h, ignore_attr = TRUE)
+})
+
+test_that("ppc_bars_data freq = FALSE returns proportions", {
+  d <- ppc_bars_data(y_ord, yrep_ord, freq = FALSE)
+  expect_true(all(d$y_obs <= 1))
+  expect_true(all(d$y_obs >= 0))
+})
+
+test_that("ppc_bars_data with group adds group column", {
+  d <- ppc_bars_data(y_ord, yrep_ord, group = group_ord)
+  expect_true("group" %in% names(d))
+  expect_s3_class(d$group, "factor")
+})
+
+test_that("ppc_bars_data prob = 0 collapses interval to median", {
+  d <- ppc_bars_data(y_ord, yrep_ord, prob = 0)
+  expect_equal(d$l, d$m, ignore_attr = TRUE)
+  expect_equal(d$m, d$h, ignore_attr = TRUE)
+})
+
+test_that("ppc_bars_data errors on NA in y", {
+  y_na <- y_ord
+  y_na[1] <- NA
+  expect_error(ppc_bars_data(y_na, yrep_ord))
+})
+
+test_that("ppc_bars_data errors on NA in yrep", {
+  yrep_na <- yrep_ord
+  yrep_na[1, 1] <- NA
+  expect_error(ppc_bars_data(y_ord, yrep_na))
+})
+
+test_that("ppc_bars_data errors on non-discrete inputs", {
+  expect_error(ppc_bars_data(y_ord + 0.5, yrep_ord),
+               "ppc_bars expects 'y' to be discrete")
+  expect_error(ppc_bars_data(y_ord, yrep_ord + 0.5),
+               "ppc_bars expects 'yrep' to be discrete")
+})
+
+test_that("ppc_bars_data errors on zero-length input", {
+  expect_error(ppc_bars_data(integer(0), matrix(integer(0), nrow = 5, ncol = 0)))
+})
+
+
+# ppc_error_data edge cases ------------------------------------------------
+
+test_that("ppc_error_data works with single observation", {
+  skip_if_not_installed("rstantools")
+  y1 <- 5
+  yrep1 <- matrix(c(4, 6, 5), ncol = 1)
+  d <- ppc_error_data(y1, yrep1)
+  expect_named(d, c("y_id", "y_name", "y_obs", "rep_id", "rep_label", "value"))
+  expect_equal(nrow(d), 3)
+  expect_equal(d$value, y1 - yrep1[, 1])
+  expect_true(all(d$y_obs == 5))
+})
+
+test_that("ppc_error_data works with single draw", {
+  skip_if_not_installed("rstantools")
+  d <- ppc_error_data(y, yrep[1, , drop = FALSE])
+  expect_equal(nrow(d), length(y))
+  expect_true(all(d$rep_id == 1))
+  expect_equal(d$value, y - yrep[1, ])
+})
+
+test_that("ppc_error_data preserves observation names", {
+  skip_if_not_installed("rstantools")
+  y_named <- c(a = 1, b = 2, c = 3)
+  yrep_named <- matrix(c(1.1, 2.1, 3.1), ncol = 3)
+  colnames(yrep_named) <- c("a", "b", "c")
+  d <- ppc_error_data(y_named, yrep_named)
+  expect_equal(as.character(d$y_name), c("a", "b", "c"))
+})
+
+test_that("ppc_error_data errors on NA in y", {
+  skip_if_not_installed("rstantools")
+  y_na <- y
+  y_na[1] <- NA
+  expect_error(ppc_error_data(y_na, yrep))
+})
+
+test_that("ppc_error_data errors on NA in yrep", {
+  skip_if_not_installed("rstantools")
+  yrep_na <- yrep
+  yrep_na[1, 1] <- NA
+  expect_error(ppc_error_data(y, yrep_na))
+})
+
+test_that("ppc_error_data errors on dimension mismatch", {
+  skip_if_not_installed("rstantools")
+  expect_error(ppc_error_data(y, yrep[, 1:5]),
+               "ncol(yrep) must be equal to length(y)", fixed = TRUE)
+})
+
+test_that("ppc_error_data returns zero-row data frame for zero-length input", {
+  skip_if_not_installed("rstantools")
+  d <- ppc_error_data(numeric(0), matrix(numeric(0), nrow = 1, ncol = 0))
+  expect_s3_class(d, "data.frame")
+  expect_equal(nrow(d), 0)
+  expect_named(d, c("y_id", "y_name", "y_obs", "rep_id", "rep_label", "value"))
+})
+
+
+# ppc_scatter_data edge cases ----------------------------------------------
+
+test_that("ppc_scatter_data returns correct structure", {
+  d <- ppc_scatter_data(y, yrep)
+  expect_s3_class(d, "data.frame")
+  expect_named(d, c("y_id", "y_name", "y_obs", "rep_id", "rep_label", "value"))
+  expect_equal(nrow(d), length(y) * nrow(yrep))
+})
+
+test_that("ppc_scatter_data works with single observation", {
+  y1 <- 5
+  yrep1 <- matrix(c(4, 6, 5), ncol = 1)
+  d <- ppc_scatter_data(y1, yrep1)
+  expect_equal(nrow(d), 3)
+  expect_true(all(d$y_obs == 5))
+  expect_equal(d$value, c(4, 6, 5))
+})
+
+test_that("ppc_scatter_data works with single draw", {
+  d <- ppc_scatter_data(y, yrep[1, , drop = FALSE])
+  expect_equal(nrow(d), length(y))
+  expect_true(all(d$rep_id == 1))
+  expect_equal(d$value, yrep[1, ])
+  expect_equal(d$y_obs, y)
+})
+
+test_that("ppc_scatter_data preserves observation names", {
+  y_named <- c(a = 1, b = 2)
+  yrep_named <- matrix(c(1.1, 2.1), ncol = 2)
+  colnames(yrep_named) <- c("a", "b")
+  d <- ppc_scatter_data(y_named, yrep_named)
+  expect_equal(as.character(d$y_name), c("a", "b"))
+})
+
+test_that("ppc_scatter_data errors on NA in y", {
+  y_na <- y
+  y_na[1] <- NA
+  expect_error(ppc_scatter_data(y_na, yrep))
+})
+
+test_that("ppc_scatter_data errors on NA in yrep", {
+  yrep_na <- yrep
+  yrep_na[1, 1] <- NA
+  expect_error(ppc_scatter_data(y, yrep_na))
+})
+
+test_that("ppc_scatter_data returns zero-row data frame for zero-length input", {
+  d <- ppc_scatter_data(numeric(0), matrix(numeric(0), nrow = 1, ncol = 0))
+  expect_s3_class(d, "data.frame")
+  expect_equal(nrow(d), 0)
+  expect_named(d, c("y_id", "y_name", "y_obs", "rep_id", "rep_label", "value"))
+})
+
+
+# ppc_scatter_avg_data edge cases ------------------------------------------
+
+test_that("ppc_scatter_avg_data returns correct structure", {
+  d <- ppc_scatter_avg_data(y, yrep)
+  expect_s3_class(d, "data.frame")
+  expect_named(d, c("y_id", "y_name", "y_obs", "rep_id", "rep_label", "value"))
+  expect_equal(nrow(d), length(y))
+  expect_true(all(is.na(d$rep_id)))
+})
+
+test_that("ppc_scatter_avg_data with group adds group column", {
+  d <- ppc_scatter_avg_data(y, yrep, group = group)
+  expect_true("group" %in% names(d))
+  expect_s3_class(d$group, "factor")
+  expect_equal(nrow(d), length(y))
+  expect_equal(as.character(d$group), as.character(group))
+})
+
+test_that("ppc_scatter_avg_data works with single observation", {
+  y1 <- 5
+  yrep1 <- matrix(c(4, 6, 5), ncol = 1)
+  d <- ppc_scatter_avg_data(y1, yrep1)
+  expect_equal(nrow(d), 1)
+  expect_equal(d$value, mean(c(4, 6, 5)))
+  expect_equal(d$y_obs, 5)
+})
+
+test_that("ppc_scatter_avg_data with custom stat function", {
+  d <- ppc_scatter_avg_data(y, yrep, stat = "median")
+  expected <- apply(yrep, 2, median)
+  expect_equal(d$value, expected)
+})
+
+test_that("ppc_scatter_avg_data errors on NA in y", {
+  y_na <- y
+  y_na[1] <- NA
+  expect_error(ppc_scatter_avg_data(y_na, yrep))
+})
+
+test_that("ppc_scatter_avg_data returns zero-row data frame for zero-length input", {
+  d <- ppc_scatter_avg_data(numeric(0), matrix(numeric(0), nrow = 1, ncol = 0))
+  expect_s3_class(d, "data.frame")
+  expect_equal(nrow(d), 0)
+})
+
+
+# ppc_loo_pit_data edge cases ----------------------------------------------
+
+test_that("ppc_loo_pit_data with pre-computed pit and boundary_correction = FALSE", {
+  set.seed(42)
+  pit_vals <- runif(30)
+  expect_message(
+    d <- ppc_loo_pit_data(pit = pit_vals, boundary_correction = FALSE, samples = 5),
+    "pit"
+  )
+  expect_s3_class(d, "data.frame")
+  y_rows <- d[d$is_y, ]
+  yrep_rows <- d[!d$is_y, ]
+  expect_equal(nrow(y_rows), length(pit_vals))
+  expect_equal(nrow(yrep_rows), length(pit_vals) * 5)
+  expect_equal(y_rows$value, pit_vals)
+  expect_true(all(d$value >= 0 & d$value <= 1))
+})
+
+test_that("ppc_loo_pit_data with pre-computed pit and boundary_correction = TRUE", {
+  set.seed(42)
+  pit_vals <- runif(30)
+  grid_len <- 128
+  expect_message(
+    d <- ppc_loo_pit_data(
+      pit = pit_vals,
+      boundary_correction = TRUE,
+      samples = 5,
+      grid_len = grid_len
+    ),
+    "pit"
+  )
+  expect_true("x" %in% names(d))
+  y_rows <- d[d$is_y, ]
+  yrep_rows <- d[!d$is_y, ]
+  expect_equal(nrow(y_rows), grid_len)
+  expect_equal(nrow(yrep_rows), grid_len * 5)
+  expect_false(anyNA(d$x))
+})
+
+test_that("ppc_loo_pit_data with single pit value and no boundary correction", {
+  expect_message(
+    d <- ppc_loo_pit_data(pit = 0.5, boundary_correction = FALSE, samples = 3),
+    "pit"
+  )
+  expect_s3_class(d, "data.frame")
+  y_rows <- d[d$is_y, ]
+  expect_equal(nrow(y_rows), 1)
+  expect_equal(y_rows$value, 0.5)
+})
+
+test_that("ppc_loo_pit_data with custom bw parameter", {
+  set.seed(42)
+  pit_vals <- runif(50)
+  expect_message(
+    d <- ppc_loo_pit_data(
+      pit = pit_vals,
+      boundary_correction = TRUE,
+      bw = "SJ",
+      samples = 3,
+      grid_len = 128
+    ),
+    "pit"
+  )
+  expect_s3_class(d, "data.frame")
+  expect_true("x" %in% names(d))
+})
+
+test_that("ppc_loo_pit_data returns zero-row data frame for zero-length pit", {
+  expect_message(
+    d <- ppc_loo_pit_data(pit = numeric(0), boundary_correction = FALSE, samples = 2),
+    "pit"
+  )
+  expect_s3_class(d, "data.frame")
+  expect_equal(nrow(d), 0)
+})
+
+test_that("ppc_loo_pit_data is_y and is_y_label columns are consistent", {
+  set.seed(42)
+  pit_vals <- runif(10)
+  expect_message(
+    d <- ppc_loo_pit_data(pit = pit_vals, boundary_correction = FALSE, samples = 2),
+    "pit"
+  )
+  expect_true(all(d$is_y_label[d$is_y] == levels(d$is_y_label)[1]))
+  expect_true(all(d$is_y_label[!d$is_y] == levels(d$is_y_label)[2]))
+})
+
+
+# ppd_data edge cases ------------------------------------------------------
+
+test_that("ppd_data works with single observation (single column)", {
+  ypred <- matrix(c(1, 2, 3), ncol = 1)
+  d <- ppd_data(ypred)
+  expect_s3_class(d, "data.frame")
+  expect_named(d, c("y_id", "y_name", "rep_id", "rep_label", "value"))
+  expect_equal(nrow(d), 3)
+  expect_true(all(d$y_id == 1))
+  expect_equal(d$value, c(1, 2, 3))
+})
+
+test_that("ppd_data rep_label uses 'pred' not 'rep'", {
+  ypred <- matrix(1:4, nrow = 2, ncol = 2)
+  d <- ppd_data(ypred)
+  expect_true(all(grepl("pred", levels(d$rep_label), fixed = TRUE)))
+  expect_false(any(grepl("rep", levels(d$rep_label), fixed = TRUE)))
+})
+
+test_that("ppd_data errors on NA in ypred", {
+  ypred_na <- matrix(c(1, NA, 3, 4), nrow = 2)
+  expect_error(ppd_data(ypred_na))
+})
+
+test_that("ppd_data errors on non-matrix input", {
+  expect_error(ppd_data(c(1, 2, 3)))
+})
+
+test_that("ppd_data with group errors on length mismatch", {
+  ypred <- matrix(1:4, nrow = 2, ncol = 2)
+  expect_error(ppd_data(ypred, group = factor(c("a", "b", "c"))))
+})
+
+test_that("ppd_data returns zero-row data frame for zero-length input", {
+  d <- ppd_data(matrix(numeric(0), nrow = 1, ncol = 0))
+  expect_s3_class(d, "data.frame")
+  expect_equal(nrow(d), 0)
+  expect_named(d, c("y_id", "y_name", "rep_id", "rep_label", "value"))
+})
+
+
+# ppd_stat_data edge cases -------------------------------------------------
+
+test_that("ppd_stat_data returns correct structure with single stat", {
+  d <- ppd_stat_data(yrep, stat = "mean")
+  expect_s3_class(d, "data.frame")
+  expect_true("value" %in% names(d))
+  expect_true("variable" %in% names(d))
+  expect_false("group" %in% names(d))
+})
+
+test_that("ppd_stat_data returns correct structure with two stats", {
+  d <- ppd_stat_data(yrep, stat = c("mean", "sd"))
+  expect_true("value" %in% names(d))
+  expect_true("value2" %in% names(d))
+})
+
+test_that("ppd_stat_data with group adds group column", {
+  d <- ppd_stat_data(yrep, group = group, stat = "mean")
+  expect_true("group" %in% names(d))
+  expect_s3_class(d$group, "factor")
+})
+
+test_that("ppd_stat_data works with single draw", {
+  yrep_single <- matrix(rnorm(10), nrow = 1)
+  d <- ppd_stat_data(yrep_single, stat = "mean")
+  expect_s3_class(d, "data.frame")
+  expect_equal(nrow(d), 1)
+})
+
+test_that("ppd_stat_data works with single observation", {
+  yrep_1obs <- matrix(rnorm(5), ncol = 1)
+  d <- ppd_stat_data(yrep_1obs, stat = "mean")
+  expect_s3_class(d, "data.frame")
+})
+
+test_that("ppd_stat_data errors on stat length > 2", {
+  expect_error(ppd_stat_data(yrep, stat = c("mean", "sd", "var")),
+               "'stat' must have length 1 or 2")
+})
+
+test_that("ppd_stat_data errors on invalid stat function name", {
+  expect_error(ppd_stat_data(yrep, stat = "not_a_known_function"))
+})
+
+test_that("ppd_stat_data errors on NA in ypred", {
+  yrep_na <- yrep
+  yrep_na[1, 1] <- NA
+  expect_error(ppd_stat_data(yrep_na, stat = "mean"))
+})
+
+test_that("ppd_stat_data errors on zero-length input", {
+  expect_error(ppd_stat_data(matrix(numeric(0), nrow = 1, ncol = 0), stat = "mean"))
+})
+
+
+# ppd_intervals_data edge cases --------------------------------------------
+
+test_that("ppd_intervals_data returns correct structure", {
+  d <- ppd_intervals_data(yrep)
+  expect_s3_class(d, "data.frame")
+  expected_cols <- c("y_id", "x", "inner_width", "outer_width",
+                     "ll", "l", "m", "h", "hh")
+  expect_true(all(expected_cols %in% names(d)))
+  expect_equal(nrow(d), ncol(yrep))
+})
+
+test_that("ppd_intervals_data works with single observation", {
+  yrep_1obs <- matrix(rnorm(25), ncol = 1)
+  d <- ppd_intervals_data(yrep_1obs)
+  expect_equal(nrow(d), 1)
+  expect_true(d$ll <= d$l)
+  expect_true(d$l <= d$m)
+  expect_true(d$m <= d$h)
+  expect_true(d$h <= d$hh)
+})
+
+test_that("ppd_intervals_data works with single draw", {
+  yrep_1draw <- matrix(rnorm(10), nrow = 1)
+  d <- ppd_intervals_data(yrep_1draw)
+  expect_equal(nrow(d), 10)
+  # single draw: all quantiles equal the value
+  expect_equal(d$ll, d$m)
+  expect_equal(d$hh, d$m)
+})
+
+test_that("ppd_intervals_data uses custom x values", {
+  x_vals <- seq(10, 100, length.out = ncol(yrep))
+  d <- ppd_intervals_data(yrep, x = x_vals)
+  expect_equal(d$x, x_vals)
+})
+
+test_that("ppd_intervals_data with group adds group column", {
+  d <- ppd_intervals_data(yrep, group = group)
+  expect_true("group" %in% names(d))
+  expect_s3_class(d$group, "factor")
+})
+
+test_that("ppd_intervals_data respects prob and prob_outer", {
+  d <- ppd_intervals_data(yrep, prob = 0.5, prob_outer = 0.9)
+  expect_equal(unique(d$inner_width), 0.5)
+  expect_equal(unique(d$outer_width), 0.9)
+})
+
+test_that("ppd_intervals_data quantile ordering holds", {
+  d <- ppd_intervals_data(yrep, prob = 0.3, prob_outer = 0.8)
+  expect_true(all(d$ll <= d$l))
+  expect_true(all(d$l <= d$m))
+  expect_true(all(d$m <= d$h))
+  expect_true(all(d$h <= d$hh))
+})
+
+test_that("ppd_intervals_data errors on NA in ypred", {
+  yrep_na <- yrep
+  yrep_na[1, 1] <- NA
+  expect_error(ppd_intervals_data(yrep_na))
+})
+
+test_that("ppd_intervals_data errors on invalid prob_outer", {
+  expect_error(ppd_intervals_data(yrep, prob_outer = 0))
+  expect_error(ppd_intervals_data(yrep, prob_outer = 1.01))
+})
+
+test_that("ppd_intervals_data returns zero-row data frame for zero-length input", {
+  d <- ppd_intervals_data(matrix(numeric(0), nrow = 1, ncol = 0))
+  expect_s3_class(d, "data.frame")
+  expect_equal(nrow(d), 0)
+})
+
+
+# ppd_ribbon_data edge cases -----------------------------------------------
+
+test_that("ppd_ribbon_data is identical to ppd_intervals_data", {
+  expect_identical(ppd_ribbon_data, ppd_intervals_data)
+})
+
+test_that("ppd_ribbon_data returns same result as ppd_intervals_data", {
+  d1 <- ppd_ribbon_data(yrep, prob = 0.5, prob_outer = 0.9)
+  d2 <- ppd_intervals_data(yrep, prob = 0.5, prob_outer = 0.9)
+  expect_identical(d1, d2)
+})

From 085bbe7e746a57a1dedfb3c618940c4f1a2fccea Mon Sep 17 00:00:00 2001
From: Utkarsh <utkarshpawadecse@gmail.com>
Date: Sat, 28 Mar 2026 16:53:58 +0530
Subject: [PATCH 2/6] Update NEWS.md with _data() edge-case test entry

---
 NEWS.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/NEWS.md b/NEWS.md
index e7fc9138..6a957b5a 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,7 +1,7 @@
 # bayesplot (development version)
 
 * Added unit tests for `mcmc_areas_ridges_data()`, `mcmc_parcoord_data()`, and `mcmc_trace_data()`.
-* Added unit tests for `ppc_error_data()` and `ppc_loo_pit_data()` covering output structure, argument handling, and edge cases.
+* Added dedicated edge-case tests for all exported `_data()` functions: `ppc_bars_data()`, `ppc_error_data()`, `ppc_scatter_data()`, `ppc_scatter_avg_data()`, `ppc_loo_pit_data()`, `ppd_data()`, `ppd_stat_data()`, `ppd_intervals_data()`, `ppd_ribbon_data()`.
 * Added vignette sections demonstrating `*_data()` companion functions for building custom ggplot2 visualizations (#435)
 * Extract `drop_singleton_values()` helper in `mcmc_nuts_treedepth()` to remove duplicated filtering logic.
 * Eliminate redundant data processing in `mcmc_areas_data()` by reusing the prepared MCMC array for both interval and density computation.

From 014e16924922cf79d01b29ca0672a728597f8e8a Mon Sep 17 00:00:00 2001
From: Utkarsh <utkarshpawadecse@gmail.com>
Date: Sat, 28 Mar 2026 16:57:14 +0530
Subject: [PATCH 3/6] update news.md

---
 NEWS.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/NEWS.md b/NEWS.md
index 6a957b5a..c91a2152 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,7 +1,8 @@
 # bayesplot (development version)
 
+* Added dedicated edge-case tests for all exported `_data()` functions.
 * Added unit tests for `mcmc_areas_ridges_data()`, `mcmc_parcoord_data()`, and `mcmc_trace_data()`.
-* Added dedicated edge-case tests for all exported `_data()` functions: `ppc_bars_data()`, `ppc_error_data()`, `ppc_scatter_data()`, `ppc_scatter_avg_data()`, `ppc_loo_pit_data()`, `ppd_data()`, `ppd_stat_data()`, `ppd_intervals_data()`, `ppd_ribbon_data()`.
+* Added unit tests for `ppc_error_data()` and `ppc_loo_pit_data()` covering output structure, argument handling, and edge cases.
 * Added vignette sections demonstrating `*_data()` companion functions for building custom ggplot2 visualizations (#435)
 * Extract `drop_singleton_values()` helper in `mcmc_nuts_treedepth()` to remove duplicated filtering logic.
 * Eliminate redundant data processing in `mcmc_areas_data()` by reusing the prepared MCMC array for both interval and density computation.

From ed8b058ae7b7082d98eacca652cfb89ac6adea92 Mon Sep 17 00:00:00 2001
From: Utkarsh <utkarshpawadecse@gmail.com>
Date: Sat, 28 Mar 2026 17:16:46 +0530
Subject: [PATCH 4/6] Add edge-case tests for exported _data() functions

---
 .../testthat/test-data-functions-edge-cases.R | 380 ++----------------
 1 file changed, 36 insertions(+), 344 deletions(-)

diff --git a/tests/testthat/test-data-functions-edge-cases.R b/tests/testthat/test-data-functions-edge-cases.R
index cce97fc2..c1154e38 100644
--- a/tests/testthat/test-data-functions-edge-cases.R
+++ b/tests/testthat/test-data-functions-edge-cases.R
@@ -1,48 +1,21 @@
 source(test_path("data-for-ppc-tests.R"))
 load(test_path("data-for-ordinal.rda"))
 
-# ppc_bars_data edge cases -------------------------------------------------
+# ppc_bars_data ------------------------------------------------------------
 
-test_that("ppc_bars_data returns correct structure and types", {
-  d <- ppc_bars_data(y_ord, yrep_ord)
-  expect_s3_class(d, "data.frame")
-  expect_named(d, c("x", "y_obs", "l", "m", "h"))
-  expect_type(d$x, "double")
-  expect_type(d$y_obs, "integer")
-  expect_type(d$l, "double")
-  expect_type(d$m, "double")
-  expect_type(d$h, "double")
-})
-
-test_that("ppc_bars_data works with single observation", {
+test_that("ppc_bars_data handles single observation and single draw", {
   y1 <- 2L
   yrep1 <- matrix(c(1L, 2L, 3L, 2L, 2L), ncol = 1)
   d <- ppc_bars_data(y1, yrep1)
   expect_s3_class(d, "data.frame")
-  expect_true(all(c("x", "y_obs") %in% names(d)))
   expect_equal(d$y_obs[d$x == 2], 1)
-})
-
-test_that("ppc_bars_data works with single draw", {
-  y_single <- c(1L, 2L, 3L, 2L)
-  yrep_single <- matrix(c(1L, 2L, 2L, 3L), nrow = 1)
-  d <- ppc_bars_data(y_single, yrep_single)
-  expect_s3_class(d, "data.frame")
-  # with single draw, l == m == h
-  expect_equal(d$l, d$m, ignore_attr = TRUE)
-  expect_equal(d$m, d$h, ignore_attr = TRUE)
-})
 
-test_that("ppc_bars_data freq = FALSE returns proportions", {
-  d <- ppc_bars_data(y_ord, yrep_ord, freq = FALSE)
-  expect_true(all(d$y_obs <= 1))
-  expect_true(all(d$y_obs >= 0))
-})
-
-test_that("ppc_bars_data with group adds group column", {
-  d <- ppc_bars_data(y_ord, yrep_ord, group = group_ord)
-  expect_true("group" %in% names(d))
-  expect_s3_class(d$group, "factor")
+  # single draw: interval collapses to a point
+  y_s <- c(1L, 2L, 3L, 2L)
+  yrep_s <- matrix(c(1L, 2L, 2L, 3L), nrow = 1)
+  d2 <- ppc_bars_data(y_s, yrep_s)
+  expect_equal(d2$l, d2$m, ignore_attr = TRUE)
+  expect_equal(d2$m, d2$h, ignore_attr = TRUE)
 })
 
 test_that("ppc_bars_data prob = 0 collapses interval to median", {
@@ -51,162 +24,57 @@ test_that("ppc_bars_data prob = 0 collapses interval to median", {
   expect_equal(d$m, d$h, ignore_attr = TRUE)
 })
 
-test_that("ppc_bars_data errors on NA in y", {
-  y_na <- y_ord
-  y_na[1] <- NA
-  expect_error(ppc_bars_data(y_na, yrep_ord))
-})
-
-test_that("ppc_bars_data errors on NA in yrep", {
-  yrep_na <- yrep_ord
-  yrep_na[1, 1] <- NA
-  expect_error(ppc_bars_data(y_ord, yrep_na))
-})
-
-test_that("ppc_bars_data errors on non-discrete inputs", {
-  expect_error(ppc_bars_data(y_ord + 0.5, yrep_ord),
-               "ppc_bars expects 'y' to be discrete")
-  expect_error(ppc_bars_data(y_ord, yrep_ord + 0.5),
-               "ppc_bars expects 'yrep' to be discrete")
-})
-
 test_that("ppc_bars_data errors on zero-length input", {
   expect_error(ppc_bars_data(integer(0), matrix(integer(0), nrow = 5, ncol = 0)))
 })
 
 
-# ppc_error_data edge cases ------------------------------------------------
+# ppc_error_data -----------------------------------------------------------
 
-test_that("ppc_error_data works with single observation", {
+test_that("ppc_error_data handles single observation", {
   skip_if_not_installed("rstantools")
   y1 <- 5
   yrep1 <- matrix(c(4, 6, 5), ncol = 1)
   d <- ppc_error_data(y1, yrep1)
-  expect_named(d, c("y_id", "y_name", "y_obs", "rep_id", "rep_label", "value"))
   expect_equal(nrow(d), 3)
   expect_equal(d$value, y1 - yrep1[, 1])
   expect_true(all(d$y_obs == 5))
 })
 
-test_that("ppc_error_data works with single draw", {
-  skip_if_not_installed("rstantools")
-  d <- ppc_error_data(y, yrep[1, , drop = FALSE])
-  expect_equal(nrow(d), length(y))
-  expect_true(all(d$rep_id == 1))
-  expect_equal(d$value, y - yrep[1, ])
-})
-
-test_that("ppc_error_data preserves observation names", {
-  skip_if_not_installed("rstantools")
-  y_named <- c(a = 1, b = 2, c = 3)
-  yrep_named <- matrix(c(1.1, 2.1, 3.1), ncol = 3)
-  colnames(yrep_named) <- c("a", "b", "c")
-  d <- ppc_error_data(y_named, yrep_named)
-  expect_equal(as.character(d$y_name), c("a", "b", "c"))
-})
-
-test_that("ppc_error_data errors on NA in y", {
-  skip_if_not_installed("rstantools")
-  y_na <- y
-  y_na[1] <- NA
-  expect_error(ppc_error_data(y_na, yrep))
-})
-
-test_that("ppc_error_data errors on NA in yrep", {
-  skip_if_not_installed("rstantools")
-  yrep_na <- yrep
-  yrep_na[1, 1] <- NA
-  expect_error(ppc_error_data(y, yrep_na))
-})
-
-test_that("ppc_error_data errors on dimension mismatch", {
-  skip_if_not_installed("rstantools")
-  expect_error(ppc_error_data(y, yrep[, 1:5]),
-               "ncol(yrep) must be equal to length(y)", fixed = TRUE)
-})
-
 test_that("ppc_error_data returns zero-row data frame for zero-length input", {
   skip_if_not_installed("rstantools")
   d <- ppc_error_data(numeric(0), matrix(numeric(0), nrow = 1, ncol = 0))
-  expect_s3_class(d, "data.frame")
   expect_equal(nrow(d), 0)
   expect_named(d, c("y_id", "y_name", "y_obs", "rep_id", "rep_label", "value"))
 })
 
 
-# ppc_scatter_data edge cases ----------------------------------------------
-
-test_that("ppc_scatter_data returns correct structure", {
-  d <- ppc_scatter_data(y, yrep)
-  expect_s3_class(d, "data.frame")
-  expect_named(d, c("y_id", "y_name", "y_obs", "rep_id", "rep_label", "value"))
-  expect_equal(nrow(d), length(y) * nrow(yrep))
-})
+# ppc_scatter_data ---------------------------------------------------------
 
-test_that("ppc_scatter_data works with single observation", {
+test_that("ppc_scatter_data handles single observation and single draw", {
   y1 <- 5
   yrep1 <- matrix(c(4, 6, 5), ncol = 1)
   d <- ppc_scatter_data(y1, yrep1)
   expect_equal(nrow(d), 3)
   expect_true(all(d$y_obs == 5))
   expect_equal(d$value, c(4, 6, 5))
-})
-
-test_that("ppc_scatter_data works with single draw", {
-  d <- ppc_scatter_data(y, yrep[1, , drop = FALSE])
-  expect_equal(nrow(d), length(y))
-  expect_true(all(d$rep_id == 1))
-  expect_equal(d$value, yrep[1, ])
-  expect_equal(d$y_obs, y)
-})
 
-test_that("ppc_scatter_data preserves observation names", {
-  y_named <- c(a = 1, b = 2)
-  yrep_named <- matrix(c(1.1, 2.1), ncol = 2)
-  colnames(yrep_named) <- c("a", "b")
-  d <- ppc_scatter_data(y_named, yrep_named)
-  expect_equal(as.character(d$y_name), c("a", "b"))
-})
-
-test_that("ppc_scatter_data errors on NA in y", {
-  y_na <- y
-  y_na[1] <- NA
-  expect_error(ppc_scatter_data(y_na, yrep))
-})
-
-test_that("ppc_scatter_data errors on NA in yrep", {
-  yrep_na <- yrep
-  yrep_na[1, 1] <- NA
-  expect_error(ppc_scatter_data(y, yrep_na))
+  # single draw
+  d2 <- ppc_scatter_data(y, yrep[1, , drop = FALSE])
+  expect_equal(nrow(d2), length(y))
+  expect_equal(d2$value, yrep[1, ])
+  expect_equal(d2$y_obs, y)
 })
 
 test_that("ppc_scatter_data returns zero-row data frame for zero-length input", {
   d <- ppc_scatter_data(numeric(0), matrix(numeric(0), nrow = 1, ncol = 0))
-  expect_s3_class(d, "data.frame")
   expect_equal(nrow(d), 0)
-  expect_named(d, c("y_id", "y_name", "y_obs", "rep_id", "rep_label", "value"))
 })
 
 
-# ppc_scatter_avg_data edge cases ------------------------------------------
-
-test_that("ppc_scatter_avg_data returns correct structure", {
-  d <- ppc_scatter_avg_data(y, yrep)
-  expect_s3_class(d, "data.frame")
-  expect_named(d, c("y_id", "y_name", "y_obs", "rep_id", "rep_label", "value"))
-  expect_equal(nrow(d), length(y))
-  expect_true(all(is.na(d$rep_id)))
-})
-
-test_that("ppc_scatter_avg_data with group adds group column", {
-  d <- ppc_scatter_avg_data(y, yrep, group = group)
-  expect_true("group" %in% names(d))
-  expect_s3_class(d$group, "factor")
-  expect_equal(nrow(d), length(y))
-  expect_equal(as.character(d$group), as.character(group))
-})
+# ppc_scatter_avg_data -----------------------------------------------------
 
-test_that("ppc_scatter_avg_data works with single observation", {
+test_that("ppc_scatter_avg_data handles single observation", {
   y1 <- 5
   yrep1 <- matrix(c(4, 6, 5), ncol = 1)
   d <- ppc_scatter_avg_data(y1, yrep1)
@@ -215,76 +83,25 @@ test_that("ppc_scatter_avg_data works with single observation", {
   expect_equal(d$y_obs, 5)
 })
 
-test_that("ppc_scatter_avg_data with custom stat function", {
-  d <- ppc_scatter_avg_data(y, yrep, stat = "median")
-  expected <- apply(yrep, 2, median)
-  expect_equal(d$value, expected)
-})
-
-test_that("ppc_scatter_avg_data errors on NA in y", {
-  y_na <- y
-  y_na[1] <- NA
-  expect_error(ppc_scatter_avg_data(y_na, yrep))
-})
-
 test_that("ppc_scatter_avg_data returns zero-row data frame for zero-length input", {
   d <- ppc_scatter_avg_data(numeric(0), matrix(numeric(0), nrow = 1, ncol = 0))
-  expect_s3_class(d, "data.frame")
   expect_equal(nrow(d), 0)
 })
 
 
-# ppc_loo_pit_data edge cases ----------------------------------------------
+# ppc_loo_pit_data ---------------------------------------------------------
 
-test_that("ppc_loo_pit_data with pre-computed pit and boundary_correction = FALSE", {
-  set.seed(42)
-  pit_vals <- runif(30)
-  expect_message(
-    d <- ppc_loo_pit_data(pit = pit_vals, boundary_correction = FALSE, samples = 5),
-    "pit"
-  )
-  expect_s3_class(d, "data.frame")
-  y_rows <- d[d$is_y, ]
-  yrep_rows <- d[!d$is_y, ]
-  expect_equal(nrow(y_rows), length(pit_vals))
-  expect_equal(nrow(yrep_rows), length(pit_vals) * 5)
-  expect_equal(y_rows$value, pit_vals)
-  expect_true(all(d$value >= 0 & d$value <= 1))
-})
-
-test_that("ppc_loo_pit_data with pre-computed pit and boundary_correction = TRUE", {
-  set.seed(42)
-  pit_vals <- runif(30)
-  grid_len <- 128
-  expect_message(
-    d <- ppc_loo_pit_data(
-      pit = pit_vals,
-      boundary_correction = TRUE,
-      samples = 5,
-      grid_len = grid_len
-    ),
-    "pit"
-  )
-  expect_true("x" %in% names(d))
-  y_rows <- d[d$is_y, ]
-  yrep_rows <- d[!d$is_y, ]
-  expect_equal(nrow(y_rows), grid_len)
-  expect_equal(nrow(yrep_rows), grid_len * 5)
-  expect_false(anyNA(d$x))
-})
-
-test_that("ppc_loo_pit_data with single pit value and no boundary correction", {
+test_that("ppc_loo_pit_data handles single pit value", {
   expect_message(
     d <- ppc_loo_pit_data(pit = 0.5, boundary_correction = FALSE, samples = 3),
     "pit"
   )
-  expect_s3_class(d, "data.frame")
   y_rows <- d[d$is_y, ]
   expect_equal(nrow(y_rows), 1)
   expect_equal(y_rows$value, 0.5)
 })
 
-test_that("ppc_loo_pit_data with custom bw parameter", {
+test_that("ppc_loo_pit_data works with custom bw parameter", {
   set.seed(42)
   pit_vals <- runif(50)
   expect_message(
@@ -297,16 +114,14 @@ test_that("ppc_loo_pit_data with custom bw parameter", {
     ),
     "pit"
   )
-  expect_s3_class(d, "data.frame")
   expect_true("x" %in% names(d))
 })
 
-test_that("ppc_loo_pit_data returns zero-row data frame for zero-length pit", {
+test_that("ppc_loo_pit_data handles zero-length pit", {
   expect_message(
     d <- ppc_loo_pit_data(pit = numeric(0), boundary_correction = FALSE, samples = 2),
     "pit"
   )
-  expect_s3_class(d, "data.frame")
   expect_equal(nrow(d), 0)
 })
 
@@ -322,95 +137,32 @@ test_that("ppc_loo_pit_data is_y and is_y_label columns are consistent", {
 })
 
 
-# ppd_data edge cases ------------------------------------------------------
+# ppd_data -----------------------------------------------------------------
 
-test_that("ppd_data works with single observation (single column)", {
+test_that("ppd_data handles single observation (single column)", {
   ypred <- matrix(c(1, 2, 3), ncol = 1)
   d <- ppd_data(ypred)
-  expect_s3_class(d, "data.frame")
-  expect_named(d, c("y_id", "y_name", "rep_id", "rep_label", "value"))
   expect_equal(nrow(d), 3)
   expect_true(all(d$y_id == 1))
   expect_equal(d$value, c(1, 2, 3))
 })
 
-test_that("ppd_data rep_label uses 'pred' not 'rep'", {
-  ypred <- matrix(1:4, nrow = 2, ncol = 2)
-  d <- ppd_data(ypred)
-  expect_true(all(grepl("pred", levels(d$rep_label), fixed = TRUE)))
-  expect_false(any(grepl("rep", levels(d$rep_label), fixed = TRUE)))
-})
-
-test_that("ppd_data errors on NA in ypred", {
-  ypred_na <- matrix(c(1, NA, 3, 4), nrow = 2)
-  expect_error(ppd_data(ypred_na))
-})
-
-test_that("ppd_data errors on non-matrix input", {
-  expect_error(ppd_data(c(1, 2, 3)))
-})
-
-test_that("ppd_data with group errors on length mismatch", {
-  ypred <- matrix(1:4, nrow = 2, ncol = 2)
-  expect_error(ppd_data(ypred, group = factor(c("a", "b", "c"))))
-})
-
 test_that("ppd_data returns zero-row data frame for zero-length input", {
   d <- ppd_data(matrix(numeric(0), nrow = 1, ncol = 0))
-  expect_s3_class(d, "data.frame")
   expect_equal(nrow(d), 0)
-  expect_named(d, c("y_id", "y_name", "rep_id", "rep_label", "value"))
-})
-
-
-# ppd_stat_data edge cases -------------------------------------------------
-
-test_that("ppd_stat_data returns correct structure with single stat", {
-  d <- ppd_stat_data(yrep, stat = "mean")
-  expect_s3_class(d, "data.frame")
-  expect_true("value" %in% names(d))
-  expect_true("variable" %in% names(d))
-  expect_false("group" %in% names(d))
 })
 
-test_that("ppd_stat_data returns correct structure with two stats", {
-  d <- ppd_stat_data(yrep, stat = c("mean", "sd"))
-  expect_true("value" %in% names(d))
-  expect_true("value2" %in% names(d))
-})
 
-test_that("ppd_stat_data with group adds group column", {
-  d <- ppd_stat_data(yrep, group = group, stat = "mean")
-  expect_true("group" %in% names(d))
-  expect_s3_class(d$group, "factor")
-})
+# ppd_stat_data ------------------------------------------------------------
 
-test_that("ppd_stat_data works with single draw", {
+test_that("ppd_stat_data handles single draw and single observation", {
   yrep_single <- matrix(rnorm(10), nrow = 1)
   d <- ppd_stat_data(yrep_single, stat = "mean")
-  expect_s3_class(d, "data.frame")
   expect_equal(nrow(d), 1)
-})
 
-test_that("ppd_stat_data works with single observation", {
   yrep_1obs <- matrix(rnorm(5), ncol = 1)
-  d <- ppd_stat_data(yrep_1obs, stat = "mean")
-  expect_s3_class(d, "data.frame")
-})
-
-test_that("ppd_stat_data errors on stat length > 2", {
-  expect_error(ppd_stat_data(yrep, stat = c("mean", "sd", "var")),
-               "'stat' must have length 1 or 2")
-})
-
-test_that("ppd_stat_data errors on invalid stat function name", {
-  expect_error(ppd_stat_data(yrep, stat = "not_a_known_function"))
-})
-
-test_that("ppd_stat_data errors on NA in ypred", {
-  yrep_na <- yrep
-  yrep_na[1, 1] <- NA
-  expect_error(ppd_stat_data(yrep_na, stat = "mean"))
+  d2 <- ppd_stat_data(yrep_1obs, stat = "mean")
+  expect_s3_class(d2, "data.frame")
 })
 
 test_that("ppd_stat_data errors on zero-length input", {
@@ -418,34 +170,19 @@ test_that("ppd_stat_data errors on zero-length input", {
 })
 
 
-# ppd_intervals_data edge cases --------------------------------------------
-
-test_that("ppd_intervals_data returns correct structure", {
-  d <- ppd_intervals_data(yrep)
-  expect_s3_class(d, "data.frame")
-  expected_cols <- c("y_id", "x", "inner_width", "outer_width",
-                     "ll", "l", "m", "h", "hh")
-  expect_true(all(expected_cols %in% names(d)))
-  expect_equal(nrow(d), ncol(yrep))
-})
+# ppd_intervals_data -------------------------------------------------------
 
-test_that("ppd_intervals_data works with single observation", {
+test_that("ppd_intervals_data handles single observation and single draw", {
   yrep_1obs <- matrix(rnorm(25), ncol = 1)
   d <- ppd_intervals_data(yrep_1obs)
   expect_equal(nrow(d), 1)
-  expect_true(d$ll <= d$l)
-  expect_true(d$l <= d$m)
-  expect_true(d$m <= d$h)
-  expect_true(d$h <= d$hh)
-})
+  expect_true(d$ll <= d$l && d$l <= d$m && d$m <= d$h && d$h <= d$hh)
 
-test_that("ppd_intervals_data works with single draw", {
+  # single draw: all quantiles collapse to the value
   yrep_1draw <- matrix(rnorm(10), nrow = 1)
-  d <- ppd_intervals_data(yrep_1draw)
-  expect_equal(nrow(d), 10)
-  # single draw: all quantiles equal the value
-  expect_equal(d$ll, d$m)
-  expect_equal(d$hh, d$m)
+  d2 <- ppd_intervals_data(yrep_1draw)
+  expect_equal(d2$ll, d2$m)
+  expect_equal(d2$hh, d2$m)
 })
 
 test_that("ppd_intervals_data uses custom x values", {
@@ -454,52 +191,7 @@ test_that("ppd_intervals_data uses custom x values", {
   expect_equal(d$x, x_vals)
 })
 
-test_that("ppd_intervals_data with group adds group column", {
-  d <- ppd_intervals_data(yrep, group = group)
-  expect_true("group" %in% names(d))
-  expect_s3_class(d$group, "factor")
-})
-
-test_that("ppd_intervals_data respects prob and prob_outer", {
-  d <- ppd_intervals_data(yrep, prob = 0.5, prob_outer = 0.9)
-  expect_equal(unique(d$inner_width), 0.5)
-  expect_equal(unique(d$outer_width), 0.9)
-})
-
-test_that("ppd_intervals_data quantile ordering holds", {
-  d <- ppd_intervals_data(yrep, prob = 0.3, prob_outer = 0.8)
-  expect_true(all(d$ll <= d$l))
-  expect_true(all(d$l <= d$m))
-  expect_true(all(d$m <= d$h))
-  expect_true(all(d$h <= d$hh))
-})
-
-test_that("ppd_intervals_data errors on NA in ypred", {
-  yrep_na <- yrep
-  yrep_na[1, 1] <- NA
-  expect_error(ppd_intervals_data(yrep_na))
-})
-
-test_that("ppd_intervals_data errors on invalid prob_outer", {
-  expect_error(ppd_intervals_data(yrep, prob_outer = 0))
-  expect_error(ppd_intervals_data(yrep, prob_outer = 1.01))
-})
-
 test_that("ppd_intervals_data returns zero-row data frame for zero-length input", {
   d <- ppd_intervals_data(matrix(numeric(0), nrow = 1, ncol = 0))
-  expect_s3_class(d, "data.frame")
   expect_equal(nrow(d), 0)
 })
-
-
-# ppd_ribbon_data edge cases -----------------------------------------------
-
-test_that("ppd_ribbon_data is identical to ppd_intervals_data", {
-  expect_identical(ppd_ribbon_data, ppd_intervals_data)
-})
-
-test_that("ppd_ribbon_data returns same result as ppd_intervals_data", {
-  d1 <- ppd_ribbon_data(yrep, prob = 0.5, prob_outer = 0.9)
-  d2 <- ppd_intervals_data(yrep, prob = 0.5, prob_outer = 0.9)
-  expect_identical(d1, d2)
-})

From 5a05326cbf3b5f8a45c75b30ce7d549a9a551680 Mon Sep 17 00:00:00 2001
From: Utkarsh <utkarshpawadecse@gmail.com>
Date: Tue, 31 Mar 2026 11:16:06 +0530
Subject: [PATCH 5/6] Move edge-case tests to existing test files

---
 NEWS.md                                       |   2 +-
 .../testthat/test-data-functions-edge-cases.R | 197 ------------------
 tests/testthat/test-ppc-discrete.R            |  21 ++
 tests/testthat/test-ppc-distributions.R       |   8 +
 tests/testthat/test-ppc-errors.R              |   9 +
 tests/testthat/test-ppc-intervals.R           |  13 ++
 tests/testthat/test-ppc-loo.R                 |   7 +
 tests/testthat/test-ppc-scatterplots.R        |  23 ++
 tests/testthat/test-ppc-test-statistics.R     |  10 +
 9 files changed, 92 insertions(+), 198 deletions(-)
 delete mode 100644 tests/testthat/test-data-functions-edge-cases.R

diff --git a/NEWS.md b/NEWS.md
index c91a2152..9a73a9db 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,6 +1,6 @@
 # bayesplot (development version)
 
-* Added dedicated edge-case tests for all exported `_data()` functions.
+* Added singleton-dimension edge-case tests for exported `_data()` functions.
 * Added unit tests for `mcmc_areas_ridges_data()`, `mcmc_parcoord_data()`, and `mcmc_trace_data()`.
 * Added unit tests for `ppc_error_data()` and `ppc_loo_pit_data()` covering output structure, argument handling, and edge cases.
 * Added vignette sections demonstrating `*_data()` companion functions for building custom ggplot2 visualizations (#435)
diff --git a/tests/testthat/test-data-functions-edge-cases.R b/tests/testthat/test-data-functions-edge-cases.R
deleted file mode 100644
index c1154e38..00000000
--- a/tests/testthat/test-data-functions-edge-cases.R
+++ /dev/null
@@ -1,197 +0,0 @@
-source(test_path("data-for-ppc-tests.R"))
-load(test_path("data-for-ordinal.rda"))
-
-# ppc_bars_data ------------------------------------------------------------
-
-test_that("ppc_bars_data handles single observation and single draw", {
-  y1 <- 2L
-  yrep1 <- matrix(c(1L, 2L, 3L, 2L, 2L), ncol = 1)
-  d <- ppc_bars_data(y1, yrep1)
-  expect_s3_class(d, "data.frame")
-  expect_equal(d$y_obs[d$x == 2], 1)
-
-  # single draw: interval collapses to a point
-  y_s <- c(1L, 2L, 3L, 2L)
-  yrep_s <- matrix(c(1L, 2L, 2L, 3L), nrow = 1)
-  d2 <- ppc_bars_data(y_s, yrep_s)
-  expect_equal(d2$l, d2$m, ignore_attr = TRUE)
-  expect_equal(d2$m, d2$h, ignore_attr = TRUE)
-})
-
-test_that("ppc_bars_data prob = 0 collapses interval to median", {
-  d <- ppc_bars_data(y_ord, yrep_ord, prob = 0)
-  expect_equal(d$l, d$m, ignore_attr = TRUE)
-  expect_equal(d$m, d$h, ignore_attr = TRUE)
-})
-
-test_that("ppc_bars_data errors on zero-length input", {
-  expect_error(ppc_bars_data(integer(0), matrix(integer(0), nrow = 5, ncol = 0)))
-})
-
-
-# ppc_error_data -----------------------------------------------------------
-
-test_that("ppc_error_data handles single observation", {
-  skip_if_not_installed("rstantools")
-  y1 <- 5
-  yrep1 <- matrix(c(4, 6, 5), ncol = 1)
-  d <- ppc_error_data(y1, yrep1)
-  expect_equal(nrow(d), 3)
-  expect_equal(d$value, y1 - yrep1[, 1])
-  expect_true(all(d$y_obs == 5))
-})
-
-test_that("ppc_error_data returns zero-row data frame for zero-length input", {
-  skip_if_not_installed("rstantools")
-  d <- ppc_error_data(numeric(0), matrix(numeric(0), nrow = 1, ncol = 0))
-  expect_equal(nrow(d), 0)
-  expect_named(d, c("y_id", "y_name", "y_obs", "rep_id", "rep_label", "value"))
-})
-
-
-# ppc_scatter_data ---------------------------------------------------------
-
-test_that("ppc_scatter_data handles single observation and single draw", {
-  y1 <- 5
-  yrep1 <- matrix(c(4, 6, 5), ncol = 1)
-  d <- ppc_scatter_data(y1, yrep1)
-  expect_equal(nrow(d), 3)
-  expect_true(all(d$y_obs == 5))
-  expect_equal(d$value, c(4, 6, 5))
-
-  # single draw
-  d2 <- ppc_scatter_data(y, yrep[1, , drop = FALSE])
-  expect_equal(nrow(d2), length(y))
-  expect_equal(d2$value, yrep[1, ])
-  expect_equal(d2$y_obs, y)
-})
-
-test_that("ppc_scatter_data returns zero-row data frame for zero-length input", {
-  d <- ppc_scatter_data(numeric(0), matrix(numeric(0), nrow = 1, ncol = 0))
-  expect_equal(nrow(d), 0)
-})
-
-
-# ppc_scatter_avg_data -----------------------------------------------------
-
-test_that("ppc_scatter_avg_data handles single observation", {
-  y1 <- 5
-  yrep1 <- matrix(c(4, 6, 5), ncol = 1)
-  d <- ppc_scatter_avg_data(y1, yrep1)
-  expect_equal(nrow(d), 1)
-  expect_equal(d$value, mean(c(4, 6, 5)))
-  expect_equal(d$y_obs, 5)
-})
-
-test_that("ppc_scatter_avg_data returns zero-row data frame for zero-length input", {
-  d <- ppc_scatter_avg_data(numeric(0), matrix(numeric(0), nrow = 1, ncol = 0))
-  expect_equal(nrow(d), 0)
-})
-
-
-# ppc_loo_pit_data ---------------------------------------------------------
-
-test_that("ppc_loo_pit_data handles single pit value", {
-  expect_message(
-    d <- ppc_loo_pit_data(pit = 0.5, boundary_correction = FALSE, samples = 3),
-    "pit"
-  )
-  y_rows <- d[d$is_y, ]
-  expect_equal(nrow(y_rows), 1)
-  expect_equal(y_rows$value, 0.5)
-})
-
-test_that("ppc_loo_pit_data works with custom bw parameter", {
-  set.seed(42)
-  pit_vals <- runif(50)
-  expect_message(
-    d <- ppc_loo_pit_data(
-      pit = pit_vals,
-      boundary_correction = TRUE,
-      bw = "SJ",
-      samples = 3,
-      grid_len = 128
-    ),
-    "pit"
-  )
-  expect_true("x" %in% names(d))
-})
-
-test_that("ppc_loo_pit_data handles zero-length pit", {
-  expect_message(
-    d <- ppc_loo_pit_data(pit = numeric(0), boundary_correction = FALSE, samples = 2),
-    "pit"
-  )
-  expect_equal(nrow(d), 0)
-})
-
-test_that("ppc_loo_pit_data is_y and is_y_label columns are consistent", {
-  set.seed(42)
-  pit_vals <- runif(10)
-  expect_message(
-    d <- ppc_loo_pit_data(pit = pit_vals, boundary_correction = FALSE, samples = 2),
-    "pit"
-  )
-  expect_true(all(d$is_y_label[d$is_y] == levels(d$is_y_label)[1]))
-  expect_true(all(d$is_y_label[!d$is_y] == levels(d$is_y_label)[2]))
-})
-
-
-# ppd_data -----------------------------------------------------------------
-
-test_that("ppd_data handles single observation (single column)", {
-  ypred <- matrix(c(1, 2, 3), ncol = 1)
-  d <- ppd_data(ypred)
-  expect_equal(nrow(d), 3)
-  expect_true(all(d$y_id == 1))
-  expect_equal(d$value, c(1, 2, 3))
-})
-
-test_that("ppd_data returns zero-row data frame for zero-length input", {
-  d <- ppd_data(matrix(numeric(0), nrow = 1, ncol = 0))
-  expect_equal(nrow(d), 0)
-})
-
-
-# ppd_stat_data ------------------------------------------------------------
-
-test_that("ppd_stat_data handles single draw and single observation", {
-  yrep_single <- matrix(rnorm(10), nrow = 1)
-  d <- ppd_stat_data(yrep_single, stat = "mean")
-  expect_equal(nrow(d), 1)
-
-  yrep_1obs <- matrix(rnorm(5), ncol = 1)
-  d2 <- ppd_stat_data(yrep_1obs, stat = "mean")
-  expect_s3_class(d2, "data.frame")
-})
-
-test_that("ppd_stat_data errors on zero-length input", {
-  expect_error(ppd_stat_data(matrix(numeric(0), nrow = 1, ncol = 0), stat = "mean"))
-})
-
-
-# ppd_intervals_data -------------------------------------------------------
-
-test_that("ppd_intervals_data handles single observation and single draw", {
-  yrep_1obs <- matrix(rnorm(25), ncol = 1)
-  d <- ppd_intervals_data(yrep_1obs)
-  expect_equal(nrow(d), 1)
-  expect_true(d$ll <= d$l && d$l <= d$m && d$m <= d$h && d$h <= d$hh)
-
-  # single draw: all quantiles collapse to the value
-  yrep_1draw <- matrix(rnorm(10), nrow = 1)
-  d2 <- ppd_intervals_data(yrep_1draw)
-  expect_equal(d2$ll, d2$m)
-  expect_equal(d2$hh, d2$m)
-})
-
-test_that("ppd_intervals_data uses custom x values", {
-  x_vals <- seq(10, 100, length.out = ncol(yrep))
-  d <- ppd_intervals_data(yrep, x = x_vals)
-  expect_equal(d$x, x_vals)
-})
-
-test_that("ppd_intervals_data returns zero-row data frame for zero-length input", {
-  d <- ppd_intervals_data(matrix(numeric(0), nrow = 1, ncol = 0))
-  expect_equal(nrow(d), 0)
-})
diff --git a/tests/testthat/test-ppc-discrete.R b/tests/testthat/test-ppc-discrete.R
index 7b0a6471..8cd20f57 100644
--- a/tests/testthat/test-ppc-discrete.R
+++ b/tests/testthat/test-ppc-discrete.R
@@ -77,6 +77,27 @@ test_that("ppc_bars_data includes all levels", {
   expect_equal(d3$h[2], 0, ignore_attr = TRUE)
 })
 
+test_that("ppc_bars_data handles single observation and single draw", {
+  y1 <- 2L
+  yrep1 <- matrix(c(1L, 2L, 3L, 2L, 2L), ncol = 1)
+  d <- ppc_bars_data(y1, yrep1)
+  expect_s3_class(d, "data.frame")
+  expect_equal(d$y_obs[d$x == 2], 1)
+
+  # single draw: interval collapses to a point
+  y_s <- c(1L, 2L, 3L, 2L)
+  yrep_s <- matrix(c(1L, 2L, 2L, 3L), nrow = 1)
+  d2 <- ppc_bars_data(y_s, yrep_s)
+  expect_equal(d2$l, d2$m, ignore_attr = TRUE)
+  expect_equal(d2$m, d2$h, ignore_attr = TRUE)
+})
+
+test_that("ppc_bars_data prob = 0 collapses interval to median", {
+  d <- ppc_bars_data(y_ord, yrep_ord, prob = 0)
+  expect_equal(d$l, d$m, ignore_attr = TRUE)
+  expect_equal(d$m, d$h, ignore_attr = TRUE)
+})
+
 
 # rootograms -----------------------------------------------------------
 yrep3 <- matrix(yrep2, nrow = 5, ncol = ncol(yrep2), byrow = TRUE)
diff --git a/tests/testthat/test-ppc-distributions.R b/tests/testthat/test-ppc-distributions.R
index 34e1c82f..c6072af2 100644
--- a/tests/testthat/test-ppc-distributions.R
+++ b/tests/testthat/test-ppc-distributions.R
@@ -221,6 +221,14 @@ test_that("ppd_data handles a single replicate matrix", {
   expect_equal(d$value, c(11, 21))
 })
 
+test_that("ppd_data handles single observation (single column)", {
+  ypred <- matrix(c(1, 2, 3), ncol = 1)
+  d <- ppd_data(ypred)
+  expect_equal(nrow(d), 3)
+  expect_true(all(d$y_id == 1))
+  expect_equal(d$value, c(1, 2, 3))
+})
+
 
 # Visual tests -----------------------------------------------------------------
 
diff --git a/tests/testthat/test-ppc-errors.R b/tests/testthat/test-ppc-errors.R
index e88c65b5..e50829b1 100644
--- a/tests/testthat/test-ppc-errors.R
+++ b/tests/testthat/test-ppc-errors.R
@@ -85,6 +85,15 @@ test_that("ppc_error_data with group returns exact structure", {
   expect_equal(d$group[d$rep_id == 1], group)
 })
 
+test_that("ppc_error_data handles single observation", {
+  y1 <- 5
+  yrep1 <- matrix(c(4, 6, 5), ncol = 1)
+  d <- ppc_error_data(y1, yrep1)
+  expect_equal(nrow(d), 3)
+  expect_equal(d$value, y1 - yrep1[, 1])
+  expect_true(all(d$y_obs == 5))
+})
+
 
 # Visual tests -----------------------------------------------------------------
 
diff --git a/tests/testthat/test-ppc-intervals.R b/tests/testthat/test-ppc-intervals.R
index a1499303..e40b66fc 100644
--- a/tests/testthat/test-ppc-intervals.R
+++ b/tests/testthat/test-ppc-intervals.R
@@ -72,6 +72,19 @@ test_that("ppd_intervals_data + y_obs column same as ppc_intervals_data", {
   expect_equal(tibble::add_column(d_group2, y_obs = d_group$y_obs, .after = "y_id"), d_group)
 })
 
+test_that("ppd_intervals_data handles single observation and single draw", {
+  yrep_1obs <- matrix(rnorm(25), ncol = 1)
+  d <- ppd_intervals_data(yrep_1obs)
+  expect_equal(nrow(d), 1)
+  expect_true(d$ll <= d$l && d$l <= d$m && d$m <= d$h && d$h <= d$hh)
+
+  # single draw: all quantiles collapse to the value
+  yrep_1draw <- matrix(rnorm(10), nrow = 1)
+  d2 <- ppd_intervals_data(yrep_1draw)
+  expect_equal(d2$ll, d2$m)
+  expect_equal(d2$hh, d2$m)
+})
+
 test_that("ppc_intervals_data does math correctly", {
   d <- ppc_intervals_data(y, yrep, prob = .4, prob_outer = .8)
   qs <- unname(quantile(yrep[, 1], c(.1, .3, .5, .7, .9)))
diff --git a/tests/testthat/test-ppc-loo.R b/tests/testthat/test-ppc-loo.R
index a722ad46..b52c6f9e 100644
--- a/tests/testthat/test-ppc-loo.R
+++ b/tests/testthat/test-ppc-loo.R
@@ -399,3 +399,10 @@ test_that("ppc_loo_pit_data returns the expected structure for both boundary mod
   expect_equal(nrow(yrep_rows), grid_len * n_samples)
   expect_false(anyNA(d_bc$x))
 })
+
+test_that("ppc_loo_pit_data works with a single pit value", {
+  d <- suppressMessages(ppc_loo_pit_data(pit = 0.5, boundary_correction = FALSE, samples = 3))
+  y_rows <- d[d$is_y, ]
+  expect_equal(nrow(y_rows), 1)
+  expect_equal(y_rows$value, 0.5)
+})
diff --git a/tests/testthat/test-ppc-scatterplots.R b/tests/testthat/test-ppc-scatterplots.R
index 02494796..e829c003 100644
--- a/tests/testthat/test-ppc-scatterplots.R
+++ b/tests/testthat/test-ppc-scatterplots.R
@@ -34,6 +34,29 @@ test_that("ppc_scatter_avg_data can take a custom fun_avg", {
   expect_equal(sums$value, colSums(yrep))
 })
 
+test_that("ppc_scatter_data handles single observation and single draw", {
+  y1 <- 5
+  yrep1 <- matrix(c(4, 6, 5), ncol = 1)
+  d <- ppc_scatter_data(y1, yrep1)
+  expect_equal(nrow(d), 3)
+  expect_true(all(d$y_obs == 5))
+  expect_equal(d$value, c(4, 6, 5))
+
+  # single draw
+  d2 <- ppc_scatter_data(y, yrep[1, , drop = FALSE])
+  expect_equal(nrow(d2), length(y))
+  expect_equal(d2$value, yrep[1, ])
+  expect_equal(d2$y_obs, y)
+})
+
+test_that("ppc_scatter_avg_data handles single observation", {
+  y1 <- 5
+  yrep1 <- matrix(c(4, 6, 5), ncol = 1)
+  d <- ppc_scatter_avg_data(y1, yrep1)
+  expect_equal(nrow(d), 1)
+  expect_equal(d$value, mean(c(4, 6, 5)))
+  expect_equal(d$y_obs, 5)
+})
 
 
 # Visual tests ------------------------------------------------------------
diff --git a/tests/testthat/test-ppc-test-statistics.R b/tests/testthat/test-ppc-test-statistics.R
index bc95ccc3..75a6dc75 100644
--- a/tests/testthat/test-ppc-test-statistics.R
+++ b/tests/testthat/test-ppc-test-statistics.R
@@ -129,6 +129,16 @@ test_that("ppc_stat_data and ppd_stat_data throw correct errors", {
                "object 'not_a_known_function' of mode 'function' was not found")
 })
 
+test_that("ppd_stat_data handles single draw and single observation", {
+  yrep_single <- matrix(rnorm(10), nrow = 1)
+  d <- ppd_stat_data(yrep_single, stat = "mean")
+  expect_equal(nrow(d), 1)
+
+  yrep_1obs <- matrix(rnorm(5), ncol = 1)
+  d2 <- ppd_stat_data(yrep_1obs, stat = "mean")
+  expect_s3_class(d2, "data.frame")
+})
+
 
 # Visual tests ------------------------------------------------------------
 

From cd0dfeefdfd551c3ab0fe523c5720eb6c3b35b58 Mon Sep 17 00:00:00 2001
From: Utkarsh <utkarshpawadecse@gmail.com>
Date: Wed, 1 Apr 2026 09:05:28 +0530
Subject: [PATCH 6/6] add nrow check for single-observation ppd_stat_data test

---
 tests/testthat/test-ppc-test-statistics.R | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/testthat/test-ppc-test-statistics.R b/tests/testthat/test-ppc-test-statistics.R
index 75a6dc75..d227c30a 100644
--- a/tests/testthat/test-ppc-test-statistics.R
+++ b/tests/testthat/test-ppc-test-statistics.R
@@ -137,6 +137,7 @@ test_that("ppd_stat_data handles single draw and single observation", {
   yrep_1obs <- matrix(rnorm(5), ncol = 1)
   d2 <- ppd_stat_data(yrep_1obs, stat = "mean")
   expect_s3_class(d2, "data.frame")
+  expect_equal(nrow(d2), 5)
 })