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Add pre-commit hook for automatic Spotless formatting #5

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Add pre-commit hook for automatic Spotless formatting #5

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538858c
Add pre-commit hook for automatic Spotless formatting
nlaverdure Jun 4, 2026
3f74e58
Skip installHooks in CI where .git directory is absent
nlaverdure Jun 4, 2026
2d7b74f
Skip installHooks when CI env var is set
nlaverdure Jun 4, 2026
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7 changes: 7 additions & 0 deletions .githooks/pre-commit
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@caparomula caparomula Jun 4, 2026

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I'm not sure that running git diff --name-only | xargs -r git add is quite the right thing. It changes the behavior of git commit to stage all modified files, not just the ones that the user had staged. Second, the xargs invocation will choke on any files with whitespace in their name.

Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
#!/bin/sh
./gradlew spotlessApply --quiet
if [ $? -ne 0 ]; then
echo "spotlessApply failed — commit aborted"
exit 1
fi
git diff --name-only | xargs -r git add
6 changes: 4 additions & 2 deletions README.md
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Expand Up @@ -72,7 +72,9 @@ Use the Gradle wrapper — no separate Gradle installation needed.

## Code Formatting

This project uses [Spotless](https://github.com/diffplug/spotless) with Google Java Format. Formatting is applied automatically on every build.
This project uses [Spotless](https://github.com/diffplug/spotless) with Google Java Format. Formatting is applied automatically on every build and on every commit (via `.githooks/pre-commit`).

The hook is installed automatically the first time you run `./gradlew build`.

**Apply formatting manually:**
```bash
Expand Down Expand Up @@ -142,7 +144,7 @@ This project is licensed under the [BSD 3-Clause License](LICENSE). See individu

### Triple Helix Robotics (FRC Team 2363)

The robot-specific subsystems and supporting utilities are original work by Triple Helix Robotics, copyright 2025.
The robot-specific subsystems and supporting utilities are original work by Triple Helix Robotics, copyright 2025-2026.

### AdvantageKit — Littleton Robotics (FRC 6328)

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7 changes: 7 additions & 0 deletions build.gradle
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Original file line number Diff line number Diff line change
Expand Up @@ -203,6 +203,13 @@ task(eventDeploy) {
}
createVersionFile.dependsOn(eventDeploy)

// Install git hooks on first build
task installHooks(type: Exec) {
onlyIf { !System.getenv("CI") }
commandLine "git", "config", "core.hooksPath", ".githooks"
}
project.compileJava.dependsOn(installHooks)

// Spotless formatting
project.compileJava.dependsOn(spotlessApply)
spotless {
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13 changes: 3 additions & 10 deletions doc/CONTRIBUTING.md
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Expand Up @@ -166,20 +166,13 @@ If `main` has changes that overlap with your branch, Git will flag conflicts. Do

### Final check before opening a PR

Run the full build and formatting check one more time before pushing. Use `./gradlew` on Mac/Linux or Git Bash; use `gradlew` in Windows Command Prompt:
Run the full build one more time before pushing. Use `./gradlew` on Mac/Linux or Git Bash; use `gradlew` in Windows Command Prompt:

```bash
./gradlew build
./gradlew spotlessCheck
```

If `spotlessCheck` fails, it means there are formatting issues. Apply the formatter automatically:

```bash
./gradlew spotlessApply
```

Review the diff, then stage and commit the formatting changes before pushing. CI will run `spotlessCheck` automatically on your PR and will fail if formatting is not clean.
Formatting is applied automatically on every commit by the pre-commit hook (installed on first build), so it should already be clean. CI will run `spotlessCheck` on your PR and will fail if formatting is not clean — if that happens, run `./gradlew spotlessApply`, commit, and push.

### Open a pull request

Expand Down Expand Up @@ -207,7 +200,7 @@ Once approved and CI is green, a mentor or senior programmer will merge the PR.

### Formatting

This project uses [Spotless](https://github.com/diffplug/spotless) with Google Java Format to keep code style consistent across the whole codebase. Formatting is applied automatically every time you run `./gradlew build`, so in most cases you do not need to think about it. If you ever want to apply it manually without building:
This project uses [Spotless](https://github.com/diffplug/spotless) with Google Java Format to keep code style consistent across the whole codebase. Formatting is applied automatically on every build and on every commit via a pre-commit hook in `.githooks/`. The hook is installed automatically the first time you run `./gradlew build`, so in most cases you do not need to think about it. If you ever want to apply it manually:

```bash
./gradlew spotlessApply
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