Fix edge cases for input entry by gdamore · Pull Request #972 · gdamore/tcell

gdamore · 2026-01-04T21:33:49Z

Summary by CodeRabbit

Release Notes

New Features
- Added support for extended UTF-8 characters, including 4-byte sequences and astral plane characters.
- Improved Alt modifier support for rune keys from escape sequences.
Bug Fixes
- Enhanced handling of terminal control sequences to prevent unintended events.
- Improved UTF-8 error recovery and extended character processing in input parsing.
Tests
- Expanded test coverage for terminal sequences and UTF-8 character handling.

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Includes more complete test coverage for various edge cases.

codecov · 2026-01-04T21:33:56Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.31%. Comparing base (80a0969) to head (3a7a49c).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #972      +/-   ##
==========================================
+ Coverage   78.85%   80.31%   +1.45%     
==========================================
  Files          38       38              
  Lines        3675     3678       +3     
==========================================
+ Hits         2898     2954      +56     
+ Misses        638      585      -53     
  Partials      139      139

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coderabbitai · 2026-01-04T21:33:58Z

📝 Walkthrough

Walkthrough

Input parsing logic is refined to detect non-ASCII characters at the 0xA0 boundary instead of 0x7F, with added ISO 2022 8-bit control handling. UTF-8 decoding error paths are improved to discard invalid leading bytes and attempt recovery. Test coverage expands to verify SMP characters, escape sequence modifiers, and terminal control sequence handling.

Changes

Cohort / File(s)	Summary
Input Scanner Logic `input.go`	Threshold for non-ASCII detection shifted from 0x7F to 0xA0 in `inputParser.scan`; ISO 2022 8-bit control handling added via istEsc state and 0x40 adjustment. UTF-8 decoding error path modified to discard invalid leading bytes (utfLen = 1) on `utf8.DecodeRune` failure and only append valid runes.
Test Expansion `input_test.go`	Added SMP UTF-8 character case in `TestInputUTF8Characters` for 4-byte sequence coverage. Extended `TestSpecialKeys` with Esc-Y case for Alt modifier verification. New `TestIgnoredSequences` suite validates parsing of terminal control sequences, DEC private mode queries, and OSC/DCS-like sequences without unintended event generation.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

test: add missing linux and extra modifier tests #944: Modifies TestSpecialKeys to add modifier-related escape sequence test cases, directly related to the Alt modifier test coverage added here.
fix: Fix input handling for ESC-char as a meta prefix. #895: Updates scanner and ScanUTF8 logic alongside escape-state handling, addressing similar control flow changes in input parsing.

Poem

🐰 With whiskers twitched at Unicode's call,
The scanner bounds now catch them all—
From 0xA0's extended dance,
To UTF-8's four-byte romance,
Each sequence tested, errors mend,
Input handling's now refined, my friend! 🎯

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 75.00% which is insufficient. The required threshold is 80.00%.	You can run `@coderabbitai generate docstrings` to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Fix edge cases for input entry' accurately reflects the main changes in the PR: modifications to input parsing logic in input.go and expanded test coverage in input_test.go to handle edge cases like ISO 2022 8-bit controls, UTF-8 boundary adjustments, and terminal control sequences.

✨ Finishing touches

📝 Generate docstrings

📜 Recent review details

Configuration used: defaults

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 80a0969 and 3a7a49c.

📒 Files selected for processing (2)

input.go
input_test.go

🧰 Additional context used

🧬 Code graph analysis (2)

input_test.go (2)

key.go (2)

KeyRune (332-332)

EventKey (46-51)

event.go (1)

Event (23-26)

input.go (1)

key.go (3)

NewEventKey (244-301)

KeyRune (332-332)

ModNone (318-318)

🔇 Additional comments (5)

input.go (2)

414-424: LGTM! ISO 2022 8-bit control handling looks correct.

The boundary change to >= 0xA0 and the new ISO 2022 C1 control handling (0x80-0x9F range) correctly maps 8-bit control sequences to their 7-bit equivalents. The state machine transition and fall-through logic properly route these through the escape sequence handler.

1058-1072: LGTM! UTF-8 error recovery strategy is sound.

The boundary change to < 0xA0 maintains consistency with scan(), and the improved error handling now discards invalid bytes without appending the replacement character. This allows the parser to recover more cleanly from malformed UTF-8 sequences by discarding one byte at a time until valid UTF-8 is found.

input_test.go (3)

324-324: Good test coverage for 4-byte UTF-8.

The SMP character test case verifies that the parser correctly handles 4-byte UTF-8 sequences, which is important edge case coverage for the UTF-8 decoding changes.

537-537: Good test for Alt modifier handling.

This test case verifies that escape sequences followed by printable characters correctly produce Alt-modified rune events, providing good coverage for the escape sequence handling logic.

706-753: Excellent test coverage for ignored terminal sequences.

The test strategy is sound: sending each ignorable sequence followed by a DECID query (as a sentinel) verifies that the parser properly consumes the sequence without generating spurious events. The coverage includes both 7-bit escape sequences and 8-bit C1 control forms, as well as error cases like invalid UTF-8.

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gdamore added 3 commits January 4, 2026 11:29

test: Add test for legacy Alt as Esc

d13f9b9

test: Add supplemental plane UTF-8 decode test

0883246

fix: recover sooner from bad UTF-8 input, support 8-bit control codes

3a7a49c

Includes more complete test coverage for various edge cases.

gdamore merged commit 3a7a49c into main Jan 4, 2026
15 checks passed

gdamore deleted the more-input-test branch January 4, 2026 21:39

gdamore temporarily deployed to github-pages January 4, 2026 21:39 — with GitHub Pages Inactive

This was referenced Jan 11, 2026

fix(windows): Windows input (paste input) may arrive as UTF-16 still … #986

Merged

tests: More test cases for input parser edge cases #1005

Merged

coderabbitai Bot mentioned this pull request Apr 11, 2026

fix(input): handle ESC during CSI and SS3 parse states per ECMA-48 #1053

Merged

coderabbitai Bot mentioned this pull request Apr 19, 2026

feat(events): add EventKey.EscSeq() for source-byte access #1059

Open

coderabbitai Bot mentioned this pull request May 4, 2026

fix(input): accept Unicode modifyOtherKeys codepoints #1083

Merged

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Fix edge cases for input entry#972

Fix edge cases for input entry#972
gdamore merged 3 commits into
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