Fix ValueError crash when tab-set contains non-tab-item children

[Copilot]

Fix tab-set crash with invalid children

Fixes #243

Summary

This PR fixes a ValueError: not enough values to unpack (expected 2, got 1) crash that occurred when a .. tab-set:: directive contained invalid content (non-tab-item children).

Changes Made

1. Modified TabSetDirective.run_with_defaults() in sphinx_design/tabs.py (lines 38-53):

• Changed from break to continue to warn about ALL invalid children, not just the first one
• Added filtering to remove invalid children from tab_set.children
• Valid tab-item directives are preserved in a new list and reassigned

2. Added defensive validation in TabSetHtmlTransform.run() in sphinx_design/tabs.py (lines 247-256):

• Added check to skip non-tab-item children that may have slipped through
• Added validation to ensure tab-item has exactly 2 children before unpacking
• Logs appropriate warnings for malformed directives

3. Added comprehensive test in tests/test_misc.py:

• Tests that tab-set with invalid children does not crash
• Verifies warnings are properly logged
• Confirms valid tab items are still processed and rendered correctly

Behavior After Fix

✅ Before: Sphinx-design crashed with ValueError when encountering invalid content in a tab-set
✅ After: Sphinx-design logs warnings for each invalid child and continues to render valid tab-items

Example input with invalid content:

.. tab-set::

   .. tab-item:: A
      A content

   foo  <-- Invalid content

   .. tab-item:: B
      B content

Result: Both valid tabs (A and B) render correctly, and a warning is logged for the invalid "foo" content.

Visual Verification

The fix was manually tested with a document containing invalid content between tab items:

All three valid tab items render and function correctly despite invalid content in the source.

Tests

All 110 tests pass, including the new test specifically for this issue:

• ✅ test_tab_set_with_invalid_children - New test reproducing and validating the fix
• ✅ All existing tests continue to pass
• ✅ All pre-commit hooks pass

Checklist

• Understand the issue and explore the codebase
• Create tests to reproduce the ValueError bug
• Fix TabSetDirective.run_with_defaults() to filter invalid children
• Add defensive validation in TabSetHtmlTransform.run()
• Run tests to verify the fix (110/110 passed)
• Verify build and lint pass
• Manual verification with visual test
• Fix pre-commit formatting issues

Original prompt

Issue

Fixes #243

Sphinx-design crashes with a ValueError: not enough values to unpack (expected 2, got 1) when a .. tab-set:: directive contains something other than .. tab-item:: directives.

Reproduction

Tab Test document
=================

.. tab-set::

   .. tab-item:: A

      A content

   foo  <-- This line causes the crash

   .. tab-item:: B

      B content

Root Cause

The problem is in sphinx_design/tabs.py:

1. In TabSetDirective.run_with_defaults() (lines 38-47): When a non-tab-item child is found, the code logs a warning but only breaks after the first invalid child. It does NOT remove the invalid children from tab_set.children.

2. In TabSetHtmlTransform.run() (line 244): The code assumes all children are valid tab-item components with exactly 2 children:

   tab_label, tab_content = tab_item.children

   When an invalid child (like a text node) is encountered, it doesn't have 2 children, causing the unpacking error.

Required Fix

1. Modify TabSetDirective.run_with_defaults() in sphinx_design/tabs.py:

Change the loop that validates children to:

• Use continue instead of break to warn about ALL invalid children, not just the first
• Filter out invalid children so only valid tab-item components remain in tab_set.children

The current code:

for item in tab_set.children:
    if not is_component(item, "tab-item"):
        LOGGER.warning(
            f"All children of a 'tab-set' "
            f"should be 'tab-item' [{WARNING_TYPE}.tab]",
            location=item,
            type=WARNING_TYPE,
            subtype="tab",
        )
        break
    if "sync_id" in item.children[0]:
        item.children[0]["sync_group"] = self.options.get("sync-group", "tab")
return [tab_set]

Should become:

valid_children = []
for item in tab_set.children:
    if not is_component(item, "tab-item"):
        LOGGER.warning(
            f"All children of a 'tab-set' "
            f"should be 'tab-item' [{WARNING_TYPE}.tab]",
            location=item,
            type=WARNING_TYPE,
            subtype="tab",
        )
        continue  # Skip invalid children instead of breaking
    if "sync_id" in item.children[0]:
        item.children[0]["sync_group"] = self.options.get("sync-group", "tab")
    valid_children.append(item)

tab_set.children = valid_children
return [tab_set]

2. Add defensive validation in TabSetHtmlTransform.run() in sphinx_design/tabs.py:

In the loop at line 242, add a check before unpacking to handle any edge cases:

for idx, tab_item in enumerate(tab_set.children):
    if not is_component(tab_item, "tab-item"):
        continue  # Skip non tab-item children
    if len(tab_item.children) != 2:
        LOGGER.warning(
            f"Malformed 'tab-item' directive [{WARNING_TYPE}.tab]",
            location=tab_item,
            type=WARNING_TYPE,
            subtype="tab",
        )
        continue
    tab_label, tab_content = tab_item.children
    # ... rest of processing unchanged

Note: You'll need to import is_component at the top of the TabSetHtmlTransform.run() method if it's not already available in that scope (it should be available since it's imported from .shared).

Expected Behavior After Fix

• Sphinx-design should NOT crash when invalid content is inside a tab-set
• A warning should be logged for each invalid child
• Valid tab-item directives should still be processed and rendered correctly
• The warning should include accurate location information

This pull request was created from Copilot chat.

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[chrisjsewell]

Fix pre-commit

[Copilot]

Fix pre-commit

Fixed in 3654e94. Pre-commit hooks now pass (trailing whitespace and ruff formatting applied).