Maintenance: DeleteToCaretAction - Add edge case handling and test coverage

[claude]

Summary

• Added edge case guard clause to DeleteToCaretAction for when caret is at position 0
• Added missing test case to verify behavior when caret is at the beginning

Area Inspected

vim-engine/src/main/kotlin/com/maddyhome/idea/vim/action/ex/DeleteToCaretAction.kt

Issues Found

1. Missing edge case handling: The implementation didn't check if caretOffset == 0 before calling deleteText, unlike similar actions (DeletePreviousWordAction, DeletePreviousCharAction)
2. Incomplete test coverage: The test file didn't cover the edge case where the caret is at position 0

Changes Made

1. Added early return when caretOffset == 0 to match the pattern used by similar command line delete actions
2. Added test case test delete at beginning does nothing to verify correct behavior at edge case
3. Extracted caretOffset to a local variable for improved readability

Why These Changes Improve the Code

• Consistency: Matches the pattern established by similar actions in the same package
• Clarity: Makes the intent explicit that nothing should be deleted when caret is at the start
• Robustness: Avoids unnecessary method calls with zero-length parameters
• Test coverage: Ensures the edge case is properly tested, preventing future regressions

References

Similar implementations that follow this pattern:

• DeletePreviousWordAction.kt:21 - if (caretOffset == 0) return true
• DeletePreviousCharAction.kt:26 - if (caretOffset == 0) return true

🤖 Generated with Claude Code

[claude]

Question about necessity of this check:

Looking at the deleteText API documentation in VimCommandLine.kt:84, it accepts offset and length parameters. When caretOffset == 0, calling deleteText(0, 0) should be a no-op (deleting zero-length text).

While I understand this change follows the pattern in DeletePreviousCharAction and DeletePreviousWordAction, those actions have different semantics:

• DeletePreviousCharAction and DeletePreviousWordAction delete backwards from the caret
• DeleteToCaretAction deletes forwards from position 0 to the caret

For backward deletion, the guard makes sense because:

1. There's computation involved (finding previous grapheme/word boundary)
2. They need to close the command line when text is empty (special behavior)

For DeleteToCaretAction, the guard is essentially an optimization to avoid a no-op call. While this is fine, it's worth confirming:

1. Does deleteText(0, 0) have any side effects that should be avoided?
2. Does the test suite verify this is actually the correct Vim behavior?

Suggestion: Consider adding a comment explaining why this early return is needed, especially if there are side effects in deleteText beyond the obvious text deletion.

[claude]

Test coverage observation:

Good addition! However, this test validates that the implementation doesn't crash or cause issues, but it doesn't strictly verify that "nothing happens" since:

1. The text is already empty after typing :
2. Pressing <C-U> on an empty command line still results in empty text

Consider adding a more explicit test case:

@Test
fun `test delete at beginning with text does nothing to caret position`() {
  typeText(":text")
  // Move caret to beginning
  typeText("<Home>")
  // Should not delete anything since caret is at position 0
  typeText("<C-U>")
  assertExText("text")
}

This would verify that when the caret is at position 0 with text present, the text remains unchanged (which is the actual edge case being guarded against).

[claude]

Code Review Summary

Thanks for this contribution! This is a well-structured maintenance PR that improves edge case handling and test coverage. Here's my detailed review:

✅ Strengths

1. Good consistency: The change follows the established pattern from similar actions (DeletePreviousCharAction, DeletePreviousWordAction)
2. Clear documentation: The PR description thoroughly explains the rationale and references similar implementations
3. Test coverage: Adding a test for the edge case is excellent practice
4. Code readability: Extracting caretOffset to a local variable improves clarity

🔍 Areas for Consideration

1. Necessity of the Guard Clause

I've left an inline comment questioning whether this guard is strictly necessary. The key difference between this action and the referenced similar actions is:

• DeletePreviousCharAction and DeletePreviousWordAction delete backwards and have additional logic (grapheme/word boundary detection, command line closing)
• DeleteToCaretAction deletes forwards from position 0 to caret

When caretOffset == 0, calling deleteText(0, 0) should be a no-op. The guard is an optimization, which is fine, but it would help to:

• Confirm if deleteText(0, 0) has any unwanted side effects
• Verify this matches actual Vim behavior (does Vim's Ctrl-U at position 0 truly do nothing special?)

2. Test Case Could Be More Explicit

The new test validates the code doesn't crash, but doesn't strictly test the edge case scenario. See my inline suggestion for a test that would verify the behavior when the caret is at position 0 with text present in the command line.

📊 Overall Assessment

Code Quality: ✅ High - Clean, follows conventions
Best Practices: ✅ Good - Consistent with codebase patterns
Potential Bugs: ⚠️ None identified, but verify Vim behavior
Performance: ✅ Minor optimization (avoiding no-op call)
Security: ✅ N/A for this change
Test Coverage: ⚠️ Good but could be more thorough

Recommendation

This is a solid maintenance improvement. I'd suggest:

1. Verify the actual Vim behavior at the command line when pressing Ctrl-U at position 0
2. Consider enhancing the test case as suggested in the inline comment
3. If there are no actual side effects from deleteText(0, 0), consider adding a comment explaining the early return is for consistency/optimization

The change is safe to merge as-is if the team is satisfied with the current approach, but the suggestions above would make it even more robust.

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Review completed by Claude Code