Add optional pre-commit hook for code formatting by jamescrosswell · Pull Request #5178 · getsentry/sentry-dotnet

jamescrosswell · 2026-05-01T02:00:56Z

Summary

Adds an optional pre-commit git hook that auto-fixes code formatting before allowing commits. This helps catch formatting issues early and reduces CI failures.

Implementation

New files:

.githooks/pre-commit: Hook script that runs dotnet format against staged .cs files only

Updated files:

dev.cs: Adds setup-hooks and remove-hooks commands to opt in/out

Behavior:

Developer runs ./dev.cs setup-hooks once to enable the hook
On each commit, the pre-commit hook runs
If unstaged changes are present → hook skips with a warning (dotnet format operates on the working tree, so partially staged files can't be handled safely)
Otherwise, dotnet format runs against staged .cs files only and auto-fixes any formatting issues
If fixes were applied → commit fails, developer stages the fixes (git add -u) and commits again
Can bypass with git commit --no-verify if needed
Run ./dev.cs remove-hooks to opt out

Design decisions:

Auto-fix: Hook applies formatting fixes rather than just reporting them — developer only needs to git add -u and recommit rather than manually running dotnet format
Staged files only: Uses --include scoped to staged .cs files so only what's being committed gets formatted
Skip on unstaged changes: If the working tree isn't clean, the hook exits with a warning rather than risking modification of unstaged hunks in partially staged files
Native git hooks: No external dependencies (Husky.NET not needed)
Opt-in via dev.cs: Discoverable through the existing dev CLI rather than a separate shell script

Addresses

Fixes #4980

Testing

✅ Hook executes on commit
✅ Hook passes when staged files are correctly formatted
✅ Hook auto-fixes formatting and blocks commit when staged files need formatting
✅ Hook skips with warning when unstaged changes are present
✅ Hook skips cleanly when no .cs files are staged
✅ ./dev.cs setup-hooks enables the hook
✅ ./dev.cs remove-hooks disables the hook

Next Steps

This PR makes the hook optional. After gathering feedback, we could:

Document in onboarding materials
Consider making it required (auto-setup on clone)
Add other pre-commit checks (analyzers, etc.)

🤖 Generated with Claude Code

Adds a pre-commit git hook that verifies code formatting before allowing commits. This helps catch formatting issues early and reduces CI failures. Implementation: - `.githooks/pre-commit`: Runs `dotnet format --verify-no-changes` - `scripts/setup-hooks.sh`: One-time setup script to configure git hooks - Updated CONTRIBUTING.md with setup instructions The hook is optional but recommended. If formatting issues are detected, the commit is prevented and the developer is prompted to run `dotnet format` manually. The hook uses the same dotnet format command as CI, ensuring consistency. Addresses #4980 Co-Authored-By: Claude Sonnet 4.5 <[email protected]>

codecov · 2026-05-01T02:17:11Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.08%. Comparing base (32a55e3) to head (d1f2687).
⚠️ Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5178      +/-   ##
==========================================
+ Coverage   74.06%   74.08%   +0.02%     
==========================================
  Files         501      506       +5     
  Lines       18113    18247     +134     
  Branches     3521     3564      +43     
==========================================
+ Hits        13415    13518     +103     
- Misses       3838     3858      +20     
- Partials      860      871      +11

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Previously the hook piped dotnet format output through grep to check for "formatted" string. This ignored the actual exit code, which meant: - If dotnet format failed for unrelated reasons (missing SDK, etc) but didn't output "formatted", the hook would pass incorrectly - The implementation diverged from how dotnet format is intended to work Now uses --verify-no-changes' exit code directly (non-zero when formatting is needed), which is more reliable and matches the tool's design. Addresses Warden feedback in review comment. Co-Authored-By: Claude Sonnet 4.5 <[email protected]>

ModuleInitializer is legitimately used in test projects for test setup (VerifyHttp initialization, EF provider registration, etc.). Test projects are effectively application code, not libraries, so this usage is appropriate. Co-Authored-By: Claude Sonnet 4.5 <[email protected]>

Changed the hook to replicate CI's approach: - Stash unstaged changes with --keep-index - Run dotnet format (no --verify-no-changes, matches CI exactly) - Check git diff to detect formatting changes - Restore stashed changes This avoids false failures from analyzer warnings (IDE1006, CA2255, etc.) and only fails on actual formatting changes that would fail CI. The stash approach handles mixed staged/unstaged changes cleanly - we only check formatting on what's being committed. Co-Authored-By: Claude Sonnet 4.5 <[email protected]>

Replace the manual stash-pop block with a `trap ... EXIT` handler so unstaged changes are restored even when `dotnet format` fails and `set -e` causes early termination. Also replace the silent `2>/dev/null || true` swallow with an explicit failure message so developers are notified when a stash-pop conflict leaves their changes in the stash. Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

When git stash pop fails due to a conflict, git leaves conflict markers in the affected files and keeps the stash entry — running stash pop again won't help. Update the warning to tell the developer to resolve the conflict markers first, then drop the stash. Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

The stash/unstash dance was error-prone (data loss on format failure, silent conflicts on pop). Just run dotnet format and block the commit if it made changes — the developer handles their own working tree. Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

Adds `./dev.cs setup-hooks` as a discoverable way to configure git to use the repo's pre-commit hooks from .githooks/. Calling git config directly in C# means it works on Windows too, replacing the Unix-only scripts/setup-hooks.sh approach. Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

Superseded by `./dev.cs setup-hooks` which does the same thing cross-platform with no duplicate logic to keep in sync. Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

Use `--include` with the list of staged .cs files so the format run only touches what's actually being committed. Unstaged WIP is left completely alone. Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

grep exits 1 on no matches, which set -e would treat as a failure. Adding || true to the assignment makes this robust regardless of pipefail settings. Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

Symmetric counterpart to setup-hooks — runs git config --unset core.hooksPath to restore default git hooks behaviour. Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

Replace the space-separated string + unquoted expansion with a bash array, passing each staged file as its own --include argument. This correctly handles paths containing spaces or shell metacharacters. Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

dotnet format operates on the working tree, not the index, so partially staged files would have their unstaged hunks modified too. Skip with a warning instead — the check still runs on clean commits (the common case). Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

- Replace removed scripts/setup-hooks.sh with ./dev.cs setup-hooks - Correct hook behaviour: auto-fixes formatting rather than verify-only - Document the unstaged changes skip behaviour - Add ./dev.cs remove-hooks opt-out instructions Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

Redirecting all output to /dev/null meant build errors or analyzer failures silently blocked the commit with no explanation. Capture output and print it only when dotnet format exits non-zero. Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

cursor

Cursor Bugbot has reviewed your changes and found 4 potential issues.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit d1f2687. Configure here.}

cursor · 2026-05-06T06:05:34Z

+INCLUDE_ARGS=()
+while IFS= read -r f; do
+  INCLUDE_ARGS+=(--include "$f")
+done < <(git diff --cached --name-only --diff-filter=ACM | grep '\.cs$' || true)


Hook blocks non-solution C# files

Medium Severity

pre-commit sends every staged *.cs path to dotnet format Sentry.slnx --include. Files outside Sentry.slnx, such as dev.cs, make dotnet format fail, so hook users cannot commit those valid repo files without bypassing the hook.

^{Reviewed by Cursor Bugbot for commit d1f2687. Configure here.}

cursor · 2026-05-06T06:05:34Z

@@ -0,0 +1,45 @@
+#!/bin/bash


Hook may break on Windows checkouts

Medium Severity

pre-commit is an extensionless Bash script, while the repo only forces LF endings for *.sh. Windows checkouts with core.autocrlf can write CRLF here, making the shebang fail before the hook runs.

^{Reviewed by Cursor Bugbot for commit d1f2687. Configure here.}

cursor · 2026-05-06T06:05:35Z

+INCLUDE_ARGS=()
+while IFS= read -r f; do
+  INCLUDE_ARGS+=(--include "$f")
+done < <(git diff --cached --name-only --diff-filter=ACM | grep '\.cs$' || true)


Renamed files skip formatting

Low Severity

--diff-filter=ACM omits staged renames, so a .cs file renamed with edits never reaches dotnet format. The hook can pass while committing unformatted renamed C# files, leaving CI to catch the formatting failure.

^{Reviewed by Cursor Bugbot for commit d1f2687. Configure here.}

cursor · 2026-05-06T06:05:35Z

+    public Task<int> SetupHooksAsync(GlobalOptions options = default!)
+    {
+        Console.WriteLine("[dev] Configuring git hooks path to .githooks/");
+        return RunStepAsync("git config core.hooksPath", "git", "config core.hooksPath .githooks", options.DryRun);


Existing hook paths get lost

Low Severity

setup-hooks overwrites any existing local core.hooksPath, and remove-hooks only unsets it. Developers with custom hook paths lose that configuration when opting in and cannot restore it through the provided opt-out command.

Additional Locations (1)

dev.cs#L116-L117

^{Reviewed by Cursor Bugbot for commit d1f2687. Configure here.}

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jamescrosswell and others added 3 commits May 4, 2026 09:40

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jamescrosswell and others added 2 commits May 4, 2026 11:19

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jamescrosswell and others added 3 commits May 4, 2026 12:22

remove: scripts/setup-hooks.sh

d3acfd4

Superseded by `./dev.cs setup-hooks` which does the same thing cross-platform with no duplicate logic to keep in sync. Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

fix(pre-commit): scope dotnet format to staged files only

ff80f08

Use `--include` with the list of staged .cs files so the format run only touches what's actually being committed. Unstaged WIP is left completely alone. Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

sentry-warden Bot reviewed May 4, 2026

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jamescrosswell and others added 4 commits May 4, 2026 13:20

fix(pre-commit): guard against grep exit code when no C# files staged

348ff62

grep exits 1 on no matches, which set -e would treat as a failure. Adding || true to the assignment makes this robust regardless of pipefail settings. Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

feat(dev): add remove-hooks command

cb7245a

Symmetric counterpart to setup-hooks — runs git config --unset core.hooksPath to restore default git hooks behaviour. Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

jamescrosswell marked this pull request as ready for review May 5, 2026 04:23

jamescrosswell requested a review from Flash0ver as a code owner May 5, 2026 04:23

sentry Bot reviewed May 5, 2026

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jamescrosswell and others added 2 commits May 6, 2026 17:52

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Summary

Implementation

Addresses

Testing

Next Steps

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Hook blocks non-solution C# files

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cursor Bot May 6, 2026

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Hook may break on Windows checkouts

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cursor Bot May 6, 2026

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Renamed files skip formatting

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cursor Bot May 6, 2026

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Existing hook paths get lost

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jamescrosswell commented May 1, 2026 •

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