Implement naming convention rule

detekt-rules/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/NamingConventionViolation.kt

@@ -0,0 +1,38 @@
+package io.gitlab.arturbosch.detekt.rules
+
+import io.gitlab.arturbosch.detekt.api.CodeSmell
+import io.gitlab.arturbosch.detekt.api.Config
+import io.gitlab.arturbosch.detekt.api.Location
+import io.gitlab.arturbosch.detekt.api.Rule
+import org.jetbrains.kotlin.psi.KtClassOrObject
+import org.jetbrains.kotlin.psi.KtNamedDeclaration
+import org.jetbrains.kotlin.psi.KtNamedFunction
+import org.jetbrains.kotlin.psi.KtVariableDeclaration
+
+/**
+ * @author Artur Bosch
+ */
+class NamingConventionViolation(config: Config = Config.EMPTY) : Rule("NamingConventionViolation", Severity.Style, config) {
+
+	private val variablePattern = Regex("^(_)?[a-z$][a-zA-Z$0-9]*$")
+	private val methodPattern = Regex("^[a-z$][a-zA-Z$0-9]*$")
+	private val classPattern = Regex("^[A-Z$][a-zA-Z$]*$")
+
+	override fun visitNamedDeclaration(declaration: KtNamedDeclaration) {
+		if (declaration.nameAsSafeName.isSpecial) return
+		declaration.nameIdentifier?.parent?.javaClass?.let {
+			val name = declaration.nameAsSafeName.asString()
+			if (declaration is KtVariableDeclaration && !name.matches(variablePattern)) {
+				addFindings(CodeSmell(id, Location.of(declaration)))
+			}
+			if (declaration is KtNamedFunction && !name.matches(methodPattern)) {
+				addFindings(CodeSmell(id, Location.of(declaration)))
+			}
+			if (declaration is KtClassOrObject && !name.matches(classPattern)) {
+				addFindings(CodeSmell(id, Location.of(declaration)))
+			}
+		}
+		super.visitNamedDeclaration(declaration)
+	}
+
+}

detekt-rules/src/test/kotlin/io/gitlab/arturbosch/detekt/rules/KT.kt

@@ -14,6 +14,7 @@ private val compiler = KtCompiler()
 enum class Case(val file: String) {
 	CasesFolder("/cases"),
 	Default("/cases/Default.kt"),
+	NamingConventions("/cases/NamingConventions.kt"),
 	ComplexClass("/cases/ComplexClass.kt"),
 	NestedClasses("/cases/NestedClasses.kt"),
 	NestedLongMethods("/cases/NestedLongMethods.kt");

detekt-rules/src/test/kotlin/io/gitlab/arturbosch/detekt/rules/NamingConventionViolationSpec.kt

@@ -0,0 +1,22 @@
+package io.gitlab.arturbosch.detekt.rules
+
+import com.natpryce.hamkrest.assertion.assertThat
+import com.natpryce.hamkrest.equalTo
+import com.natpryce.hamkrest.hasSize
+import org.jetbrains.spek.api.SubjectSpek
+import org.jetbrains.spek.api.dsl.it
+
+/**
+ * @author Artur Bosch
+ */
+class NamingConventionViolationSpec : SubjectSpek<NamingConventionViolation>({
+	subject { NamingConventionViolation() }
+
+	it("should find all wrong namings") {
+		val root = load(Case.NamingConventions)
+		subject.visit(root)
+		subject.findings.map { it.compact() }.forEach { println(it) }
+		assertThat(subject.findings, hasSize(equalTo(9)))
+	}
+
+})

detekt-rules/src/test/resources/cases/NamingConventions.kt

@@ -0,0 +1,37 @@
+package cases
+
+// both valid
+val variable = 5
+val _variable = 5
+// invalid start with _ is optional, but then lowercase!
+val V_riable = 5
+val _Variable = 5
+
+//valid
+fun fileMethod() {
+}
+//invalid
+fun FileMethod() {
+}
+fun _fileMethod() {
+}
+
+@Suppress("unused")
+class NamingConventions {
+
+	//invalid
+	val C_lassVariable = 5
+	//valid
+	val _classVariable = 5
+	val classVariable = 5
+	fun classMethod(){
+	}
+	//invalid
+	fun _classmethod(){
+	}
+	fun Classmethod(){
+	}
+}
+//invalid
+class _NamingConventions{}
+class namingConventions{}