#145 Enforce unit test naming to snake case

build.gradle

@@ -1,13 +1,16 @@
+import dev.sorn.fmp4j.CoveragePlugin
+import dev.sorn.fmp4j.SnakeCaseMethodFormatter
+
 plugins {
     id 'java-library'
     id 'java-test-fixtures'
     id 'checkstyle'
     id 'jacoco'
     id 'com.vanniktech.maven.publish' version '0.34.0'
-    id 'com.diffplug.spotless' version '7.2.0'
+    id 'com.diffplug.spotless'
 }
 
-apply plugin: dev.sorn.fmp4j.CoveragePlugin
+apply plugin: CoveragePlugin
 
 group = 'dev.sorn.fmp4j'
 version = projectVersion
@@ -18,6 +21,12 @@ java {
     }
 }
 
+spotless {
+    java {
+        addStep(new SnakeCaseMethodFormatter())
+    }
+}
+
 repositories {
     mavenCentral()
 }
@@ -28,6 +37,8 @@ dependencies {
     implementation("com.fasterxml.jackson.core:jackson-databind:${jacksonVersion}")
     implementation("org.apache.httpcomponents.client5:httpclient5:${apacheHttpComponentsVersion}")
     implementation("org.apache.commons:commons-lang3:${apacheCommonsVersion}")
+    implementation("com.diffplug.spotless:spotless-plugin-gradle:${spotlessVersion}")
+
     testImplementation("org.mockito:mockito-core:${mockitoCoreVersion}")
     testImplementation("org.mockito:mockito-junit-jupiter:${mockitoJunitVersion}")
     testImplementation(platform("org.junit:junit-bom:${junitVersion}"))

buildSrc/build.gradle

@@ -9,4 +9,6 @@ repositories {
 dependencies {
     implementation gradleApi()
     implementation localGroovy()
+    implementation("com.diffplug.spotless:spotless-plugin-gradle:${spotlessVersion}")
+    implementation("com.github.javaparser:javaparser-core:${javaparserVersion}")
 }

buildSrc/gradle.properties

@@ -0,0 +1,2 @@
+spotlessVersion=7.2.0
+javaparserVersion=3.27.0

buildSrc/src/main/java/dev/sorn/fmp4j/SnakeCaseMethodFormatter.java

@@ -0,0 +1,94 @@
+package dev.sorn.fmp4j;
+
+import com.diffplug.spotless.FormatterStep;
+import com.github.javaparser.ParserConfiguration;
+import com.github.javaparser.StaticJavaParser;
+import com.github.javaparser.ast.CompilationUnit;
+import com.github.javaparser.ast.body.MethodDeclaration;
+import com.github.javaparser.ast.expr.AnnotationExpr;
+import com.github.javaparser.ParserConfiguration.LanguageLevel;
+import java.io.File;
+import java.io.Serial;
+import java.util.List;
+import java.util.regex.Pattern;
+
+
+public class SnakeCaseMethodFormatter implements FormatterStep {
+    @Serial
+    private static final long serialVersionUID = 1L;
+
+    // Set of annotations that identify a method as a unit test
+    private static final List<String> TEST_ANNOTATIONS = List.of(
+            "Test",              // JUnit 4 & 5
+            "ParameterizedTest", // JUnit 5
+            "RepeatedTest",      // JUnit 5
+            "TestFactory"        // JUnit 5
+    );
+
+    private static final Pattern SNAKE_CASE_PATTERN = Pattern.compile("^[a-z][a-z0-9_]*$");
+
+    private static final ParserConfiguration parserConfig = new ParserConfiguration()
+            .setLanguageLevel(LanguageLevel.JAVA_17);;
+
+    @Override
+    public String getName() {
+        return "Unit test Naming Enforcement (snake_case)";
+    }
+
+    @Override
+    public String format(String rawUnix, File file) throws Exception {
+        // 1. Parse the source code into an AST
+        StaticJavaParser.setConfiguration(parserConfig);
+        CompilationUnit cu = StaticJavaParser.parse(rawUnix);
+
+        // 2. Walk through all method declarations in the file
+        boolean changed = false;
+        for (MethodDeclaration method : cu.findAll(MethodDeclaration.class)) {
+            if (isUnitTest(method)) {
+                String oldName = method.getNameAsString();
+
+                // 3. Check if the name complies with snake_case
+                if (!SNAKE_CASE_PATTERN.matcher(oldName).matches()) {
+                    String newName = toSnakeCase(oldName);
+                    method.setName(newName);
+                    changed = true;
+                }
+            }
+        }
+
+        // 4. Return the modified source only if changes were made, else return original
+        // (Parsing/printing can sometimes shift whitespace, so we prefer returning original if untouched)
+        return changed ? cu.toString() : rawUnix;
+    }
+
+    /**
+     * Checks if the method is annotated with one of the known test annotations.
+     */
+    private boolean isUnitTest(MethodDeclaration method) {
+        for (AnnotationExpr annotation : method.getAnnotations()) {
+            if (TEST_ANNOTATIONS.contains(annotation.getNameAsString())) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Converts a camelCase string to snake_case.
+     * Example: "testUserProfile" -> "test_user_profile"
+     */
+    private String toSnakeCase(String input) {
+        // Regex to look for instances of LowerUpper (e.g. "tU") and insert underscore
+        String regex = "([a-z])([A-Z]+)";
+        String replacement = "$1_$2";
+
+        // Apply replacement and convert to lowercase
+        return input.replaceAll(regex, replacement).toLowerCase();
+    }
+
+    @Override
+    public void close() throws Exception {
+
+    }
+}
+

gradle.properties

@@ -8,6 +8,7 @@ apacheCommonsVersion=3.18.0
 apacheHttpComponentsVersion=5.5
 jacksonVersion=2.19.2
 jacksonCsvVersion=2.17.2
+spotlessVersion=7.2.0
 
 # Publishing
 mavenCentralPublishing=true

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,7 @@
-#Fri Aug 15 20:38:05 GST 2025
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.13-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.2.1-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists