test: add regression tests for issue #279 (facet_wrap spacing with custom height)

tests/testthat/test-issue-279-facet-wrap-custom-height-spacing.R

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+context("Issue #279: facet_wrap spacing with custom height")
+
+test_that("facet_wrap vertical layout height scales proportionally with custom height parameter (#279)", {
+  skip_on_cran()
+
+  # Create simple test data with 2 facets for vertical layout  
+  # This setup is most likely to show excessive spacing issues
+  test_data <- data.frame(
+    x = c(1, 5, 10, 1, 5, 10),
+    y = c(1, 5, 10, 1, 5, 10),
+    category = c("A", "A", "A", "B", "B", "B")
+  )
+
+  # Test Case 1: Default height (baseline for comparison)
+  viz_default <- ggplot() +
+    geom_point(aes(x, y), data = test_data, size = 3) +
+    facet_wrap(~category, ncol = 1) +  # Vertical layout
+    ggtitle("Default height")
+
+  # Test Case 2: Custom height (2x default)
+  viz_custom_800 <- ggplot() +
+    geom_point(aes(x, y), data = test_data, size = 3) +
+    facet_wrap(~category, ncol = 1) +
+    theme_animint(height = 800) +  # 2x default 400
+    ggtitle("Custom height 800")
+
+  # Test Case 3: Custom height (3x default)
+  viz_custom_1200 <- ggplot() +
+    geom_point(aes(x, y), data = test_data, size = 3) +
+    facet_wrap(~category, ncol = 1) +
+    theme_animint(height = 1200) +  # 3x default 400
+    ggtitle("Custom height 1200")
+
+  # Render all three visualizations
+  dir_default <- tempfile()
+  dir_800 <- tempfile()
+  dir_1200 <- tempfile()
+
+  info_default <- animint2dir(
+    list(plot = viz_default), 
+    out.dir = dir_default,
+    open.browser = FALSE
+  )
+
+  info_800 <- animint2dir(
+    list(plot = viz_custom_800), 
+    out.dir = dir_800,
+    open.browser = FALSE
+  )
+
+  info_1200 <- animint2dir(
+    list(plot = viz_custom_1200), 
+    out.dir = dir_1200,
+    open.browser = FALSE
+  )
+
+  # Read the generated plot.json files to verify height settings
+  json_default <- jsonlite::fromJSON(file.path(dir_default, "plot.json"))
+  json_800 <- jsonlite::fromJSON(file.path(dir_800, "plot.json"))
+  json_1200 <- jsonlite::fromJSON(file.path(dir_1200, "plot.json"))
+
+  # Verify that custom heights are correctly stored in plot.json
+  expect_equal(json_800$plots$plot$options$height, 800)
+  expect_equal(json_1200$plots$plot$options$height, 1200)
+
+  # The bug in issue #279 was: excessive vertical spacing below facets
+  # when using custom height != 400 (default)
+  # Expected behavior: spacing should scale proportionally, not excessively
+
+  # We verify this indirectly by checking that the layout information
+  # is consistent across different height values
+
+  # Check that panel layout is identical (same number of rows/cols)
+  expect_equal(json_default$plots$plot$layout$ROW, json_800$plots$plot$layout$ROW)
+  expect_equal(json_default$plots$plot$layout$ROW, json_1200$plots$plot$layout$ROW)
+  expect_equal(json_default$plots$plot$layout$COL, json_800$plots$plot$layout$COL)
+  expect_equal(json_default$plots$plot$layout$COL, json_1200$plots$plot$layout$COL)
+
+  # Check that height_proportion values are identical
+  # (these control relative spacing, not absolute)
+  expect_equal(json_default$plots$plot$layout$height_proportion, 
+               json_800$plots$plot$layout$height_proportion)
+  expect_equal(json_default$plots$plot$layout$height_proportion,
+               json_1200$plots$plot$layout$height_proportion)
+})
+
+test_that("facet_wrap grid layout (2x2) with custom height has proportional spacing (#279)", {
+  skip_on_cran()
+
+  # Test with a 2x2 grid layout (similar to ROC example in issue)
+  test_data_grid <- data.frame(
+    x = rep(1:10, 4),
+    y = rep(1:10, 4),
+    category = rep(c("A", "B", "C", "D"), each = 10)
+  )
+
+  # Default height
+  viz_default <- ggplot() +
+    geom_point(aes(x, y), data = test_data_grid) +
+    facet_wrap(~category, ncol = 2)
+
+  # Custom height (1.5x default)
+  viz_custom <- ggplot() +
+    geom_point(aes(x, y), data = test_data_grid) +
+    facet_wrap(~category, ncol = 2) +
+    theme_animint(height = 600)
+
+  dir_default <- tempfile()
+  dir_custom <- tempfile()
+
+  info_default <- animint2dir(list(plot = viz_default), out.dir = dir_default, open.browser = FALSE)
+  info_custom <- animint2dir(list(plot = viz_custom), out.dir = dir_custom, open.browser = FALSE)
+
+  # Verify custom height is applied
+  json_custom <- jsonlite::fromJSON(file.path(dir_custom, "plot.json"))
+  expect_equal(json_custom$plots$plot$options$height, 600)
+
+  # Check that layout proportions are consistent
+  json_default <- jsonlite::fromJSON(file.path(dir_default, "plot.json"))
+  expect_equal(json_default$plots$plot$layout$height_proportion,
+               json_custom$plots$plot$layout$height_proportion)
+
+  # Verify we have 2 rows and 2 columns as expected
+  expect_equal(max(json_custom$plots$plot$layout$ROW), 2)
+  expect_equal(max(json_custom$plots$plot$layout$COL), 2)
+})
+
+test_that("facet_wrap with multiple custom height values maintains proportional spacing (#279)", {
+  skip_on_cran()
+
+  # Test that spacing proportions are maintained across various custom heights
+  test_data <- data.frame(
+    x = c(1, 5, 10, 1, 5, 10),
+    y = c(1, 5, 10, 1, 5, 10),
+    category = c("X", "X", "X", "Y", "Y", "Y")
+  )
+
+  heights_to_test <- c(400, 600, 800, 1000, 1200)
+  layout_proportions <- list()
+
+  for (i in seq_along(heights_to_test)) {
+    h <- heights_to_test[i]
+
+    if (h == 400) {
+      # Default height
+      viz <- ggplot() +
+        geom_point(aes(x, y), data = test_data) +
+        facet_wrap(~category, ncol = 1)
+    } else {
+      # Custom height
+      viz <- ggplot() +
+        geom_point(aes(x, y), data = test_data) +
+        facet_wrap(~category, ncol = 1) +
+        theme_animint(height = h)
+    }
+
+    test_dir <- tempfile()
+    info <- animint2dir(list(plot = viz), out.dir = test_dir, open.browser = FALSE)
+
+    # Extract layout proportions
+    json <- jsonlite::fromJSON(file.path(test_dir, "plot.json"))
+    layout_proportions[[i]] <- json$plots$plot$layout$height_proportion
+  }
+
+  # All layout proportions should be identical
+  # (height should scale, but proportions should remain constant)
+  for (i in 2:length(layout_proportions)) {
+    expect_equal(layout_proportions[[1]], layout_proportions[[i]],
+                 info = sprintf("Height %d proportions differ from default (400)", heights_to_test[i]))
+  }
+})