Use Spotless formatting

Author: jupblb

.github/workflows/nix.yaml

@@ -31,6 +31,20 @@ jobs:
 
       - run: nix flake check -L
 
+  format:
+    runs-on: ubuntu-latest
+    name: Formatting
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: DeterminateSystems/nix-installer-action@v22
+        with:
+          summarize: false
+
+      - uses: DeterminateSystems/magic-nix-cache-action@v13
+
+      - run: gradle spotlessCheck --no-daemon
+
   test:
     runs-on: ubuntu-latest
     name: Tests (JDK ${{ matrix.java }})

CONTRIBUTING.md

@@ -58,8 +58,8 @@ These are the main components of the project.
 | `gradle :scip-snapshots:saveSnapshots --no-daemon`      | terminal | Regenerate Java and Kotlin snapshot goldens.                             |
 | `gradle :scip-java:installDist --no-daemon`             | terminal | Build a local `scip-java` distribution under `scip-java/build/install/`. |
 | `gradle :scip-java:run --args='--cwd DIRECTORY'`        | terminal | Run `scip-java` against a given Gradle/Maven build.                      |
-| `google-java-format --replace $(git ls-files '*.java')` | terminal | Format Java sources (from `nix develop`). Enforced by `nix flake check`. |
-| `ktfmt --kotlinlang-style $(git ls-files '*.kt')`       | terminal | Format Kotlin sources (from `nix develop`). Enforced by `nix flake check`. |
+| `gradle format`                                         | terminal | Format Java and Kotlin sources with Spotless.                            |
+| `gradle spotlessCheck`                                  | terminal | Check Java and Kotlin formatting. Enforced by GitHub Actions.            |
 
 ## Import the project into IntelliJ
 

build.gradle.kts

@@ -1,5 +1,29 @@
+plugins {
+    alias(libs.plugins.spotless)
+}
+
 tasks.register("saveSnapshots") {
     group = "verification"
     description = "Regenerates all SCIP snapshot goldens."
     dependsOn(":scip-snapshots:saveSnapshots")
 }
+
+spotless {
+    java {
+        target("scip-*/src/**/*.java")
+        targetExclude("scip-java/src/test/resources/fixtures/**")
+        googleJavaFormat("1.28.0")
+    }
+
+    kotlin {
+        target("build-logic/src/**/*.kt", "scip-*/src/**/*.kt")
+        targetExclude("scip-java/src/test/resources/fixtures/**")
+        ktfmt("0.61").kotlinlangStyle()
+    }
+}
+
+tasks.register("format") {
+    group = "formatting"
+    description = "Formats Java and Kotlin sources."
+    dependsOn("spotlessApply")
+}

flake.nix

@@ -29,11 +29,9 @@
             buildInputs = with pkgs; [
               bazelisk
               git
-              google-java-format
               (gradle_9.override ({ java = jdk; }))
               jdk
               jq
-              ktfmt
               (maven.override ({ jdk_headless = jdk; }))
               nixfmt
               nodejs
@@ -48,33 +46,6 @@
             ${pkgs.actionlint}/bin/actionlint ${./.github/workflows}/*.yaml
             touch $out
           '';
-          javafmt = pkgs.runCommand "check-javafmt" { } ''
-            cd ${./.}
-            # Exclude minimized fixtures and generated SCIP snapshot goldens
-            # (coupled to exact line/column annotations), the standalone example
-            # projects, and the scip-java build-tool test fixtures: these all mirror
-            # real-world project layouts that must not be reformatted here.
-            find . -name '*.java' \
-              -not -path './examples/*' \
-              -not -path './scip-snapshots/cases/*' \
-              -not -path './scip-snapshots/expected/*' \
-              -not -path './scip-java/src/test/resources/fixtures/*' \
-              -exec ${pkgs.google-java-format}/bin/google-java-format --dry-run --set-exit-if-changed {} +
-            touch $out
-          '';
-          ktfmt = pkgs.runCommand "check-ktfmt" { } ''
-            cd ${./.}
-            # Exclude minimized Kotlin snapshots (coupled to generated SCIP
-            # goldens with exact line/column annotations) and the scip-java
-            # build-tool test fixtures (real-world project layouts): neither may
-            # be reformatted.
-            find . -name '*.kt' \
-              -not -path './scip-snapshots/cases/*' \
-              -not -path './scip-snapshots/expected/*' \
-              -not -path './scip-java/src/test/resources/fixtures/*' \
-              -exec ${pkgs.ktfmt}/bin/ktfmt --kotlinlang-style --dry-run --set-exit-if-changed {} +
-            touch $out
-          '';
           nixfmt = pkgs.runCommand "check-nixfmt" { } ''
             ${pkgs.nixfmt}/bin/nixfmt --check ${./flake.nix}
             touch $out

gradle/libs.versions.toml

@@ -14,6 +14,7 @@ protobuf = "4.34.2"
 protobuf-plugin = "0.10.0"
 scip-bindings = "0.8.0"
 shadow = "9.4.3"
+spotless = "8.7.0"
 vanniktech-maven-publish = "0.35.0"
 
 [libraries]
@@ -43,4 +44,5 @@ scip-kotlin-bindings = { module = "org.scip-code:scip-kotlin-bindings", version.
 kotlin-jvm = { id = "org.jetbrains.kotlin.jvm", version.ref = "kotlin" }
 protobuf = { id = "com.google.protobuf", version.ref = "protobuf-plugin" }
 shadow = { id = "com.gradleup.shadow", version.ref = "shadow" }
+spotless = { id = "com.diffplug.spotless", version.ref = "spotless" }
 vanniktech-maven-publish = { id = "com.vanniktech.maven.publish", version.ref = "vanniktech-maven-publish" }