test: add failing tests for check_model() theme argument bug (#851) #869

ANAMASGARD · 2025-10-24T14:24:57Z

Tests document expected behavior of theme argument
Tests currently FAIL due to bugs in see package
Covers: standard themes, custom themes, string themes, attribute storage
Bug is in see/R/plot.check_model.R (hardcoded args issue)

Relates to #851

…ts#851) - Tests document expected behavior of theme argument - Tests currently FAIL due to bugs in see package - Covers: standard themes, custom themes, string themes, attribute storage - Bug is in see/R/plot.check_model.R (hardcoded args issue) Relates to easystats#851

gemini-code-assist · 2025-10-24T14:25:09Z

Summary of Changes

Hello @ANAMASGARD, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request adds a comprehensive set of failing tests to pinpoint and document a critical bug in the check_model() function's theme argument. The tests cover various scenarios, including standard ggplot2 themes, string-based theme references, and custom theme functions, all of which currently fail due to issues within the see package's plotting mechanism. The primary goal is to provide clear, reproducible examples of the bug, facilitating its eventual fix.

Highlights

New Failing Tests: Introduced a new test file test-check_model_theme.R containing six test cases that currently fail, specifically designed to expose a bug in the check_model() function's theme argument within the see package.
Theme Argument Issues: The tests demonstrate problems with check_model()'s theme argument, including failures when applying standard ggplot2 themes (due to 'unused arguments' errors), issues with themes passed as strings, and an inability to access custom user-defined theme functions.
Attribute Storage and Override: The new tests also verify that the theme attribute is correctly stored and retrieved by check_model(), and that the style argument in the plot() method can successfully override the theme set during the initial check_model() call.
Bug Location Identified: The pull request explicitly points out that the underlying bug is located in the see package's R/plot.check_model.R file, specifically around lines 64-67, related to hardcoded arguments.

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Code Review

This pull request introduces a new test file (test-check_model_theme.R) to address issue #851, which concerns the theme argument in the check_model() function not working as expected. The tests cover various scenarios, including standard ggplot2 themes, custom themes, and theme attribute storage. The tests are currently failing due to bugs in the see package, as noted in the pull request description. The pull request provides a comprehensive set of tests to validate the expected behavior of the theme argument once the underlying bugs in the see package are resolved.

gemini-code-assist · 2025-10-24T14:26:24Z

tests/testthat/test-check_model_theme.R

+
+  # Test with theme_dark passed as function (not string)
+  expect_no_error({
+    p1 <- check_model(m, theme = ggplot2::theme_dark)


It's good to see the explicit namespace call here (ggplot2::theme_dark). This ensures that the correct theme is being called, especially in environments where multiple packages might have functions with the same name. However, consider adding a comment to explain why the namespace is explicitly called out, as it might not be obvious to future readers.

p1 <- check_model(m, theme = ggplot2::theme_dark) # Explicit namespace call for clarity and to avoid conflicts

gemini-code-assist · 2025-10-24T14:26:24Z

tests/testthat/test-check_model_theme.R

+  theme_attr <- attr(p1, "theme")
+  expect_true(is.function(theme_attr) || is.character(theme_attr))


This assertion checks that the theme attribute is either a function or a character. While this is a good start, consider adding a more specific check to ensure that the function or character value corresponds to a valid theme. For example, if it's a character, check if the theme exists in the ggplot2 namespace. If it's a function, check if it returns a ggplot2 theme object.

theme_attr <- attr(p1, "theme") expect_true(is.function(theme_attr) || is.character(theme_attr)) # Add more specific checks to validate the theme if (is.character(theme_attr)) { expect_true(exists(theme_attr, where = asNamespace("ggplot2")), info = "Theme string should exist in ggplot2 namespace") } else if (is.function(theme_attr)) { expect_s3_class(theme_attr(), "theme", info = "Theme function should return a ggplot2 theme object") }

gemini-code-assist · 2025-10-24T14:26:24Z

tests/testthat/test-check_model_theme.R

+  # Test with string
+  p2 <- check_model(m, theme = "ggplot2::theme_minimal")
+  expect_true(!is.null(attr(p2, "theme")))
+  expect_equal(attr(p2, "theme"), "ggplot2::theme_minimal")


This test uses expect_equal to check if the theme attribute is stored correctly as a string. While this works, it might be more robust to use expect_identical to ensure that the attribute is exactly the same, including its attributes. This can help catch subtle differences that expect_equal might miss.

p2 <- check_model(m, theme = "ggplot2::theme_minimal") expect_true(!is.null(attr(p2, "theme"))) expect_identical(attr(p2, "theme"), "ggplot2::theme_minimal") # Use expect_identical for stricter comparison

gemini-code-assist · 2025-10-24T14:26:24Z

tests/testthat/test-check_model_theme.R

+# -----------------------------------------------------------------------------
+# This tests that the plot method's style parameter can override the theme
+# set during check_model() call.
+test_that("plot style argument overrides check_model theme", {


Consider adding a comment to clarify the purpose of this test. It's not immediately obvious why we're testing the default theme behavior separately. A brief explanation can help improve the test's readability and maintainability.

# Test 5: Default theme should work when no theme specified # ----------------------------------------------------------------------------- # Tests that check_model works correctly when no theme argument is provided, # ensuring it falls back to the default theme. test_that("check_model works without theme argument (default behavior)", {

…ats#851) Tests document expected behavior of theme argument: - Standard ggplot2 themes (theme_dark, theme_minimal, theme_bw) - Custom user-defined theme functions - Theme as string for backward compatibility - Theme attribute storage and retrieval Changes from review: - Remove trailing whitespace - Add namespace clarity comments - Use expect_identical for stricter comparison - Validate theme functions return theme objects - Add explanatory comment for default theme test Note: The actual bug is in the see package's plot.check_model() function which passes hardcoded arguments that don't exist in standard ggplot2 themes. This requires a fix in the see repository. Relates to easystats#851

ANAMASGARD · 2025-10-24T14:53:30Z

Current Status

This PR adds comprehensive failing tests that document the expected behavior of the theme argument in check_model(). These tests are intentionally failing as part of a Test-Driven Development (TDD) approach.

Root Cause Location

The actual bug is not in the performance package - it's in the see package's plotting mechanism:

Bug Location: easystats/see → R/plot.check_model.R (approximately lines 64-67)

Problem: The plot.see_check_model() method tries to call theme functions with hardcoded arguments like plot.title.space and axis.title.space that don't exist in standard ggplot2 themes, causing "unused arguments" errors.

What This PR Provides

✅ Comprehensive test coverage documenting three bug scenarios:

Standard ggplot2 themes (theme_dark, theme_minimal, theme_bw)
Themes passed as strings (backward compatibility)
Custom user-defined theme functions

✅ Tests validate:

Theme attribute storage and retrieval
Default theme behavior
Style argument override functionality

Next Steps

I plan to:

✅ Get this test PR reviewed and merged (or guidance on improvements)
🔄 Create a corresponding PR in the see repository with the actual bug fix
🔄 Link both PRs together so they can be reviewed/merged in coordination

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		theme_attr <- attr(p1, "theme")
		expect_true(is.function(theme_attr) \|\| is.character(theme_attr))

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ANAMASGARD commented Oct 24, 2025

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ANAMASGARD commented Oct 24, 2025

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