add test-library and ktlint

src/main/kotlin/de/hoennig/gittally/GitTallyApplication.kt

@@ -1,22 +1,32 @@
 package de.hoennig.gittally
 
 import org.springframework.boot.CommandLineRunner
+import org.springframework.boot.ExitCodeGenerator
+import org.springframework.boot.SpringApplication
 import org.springframework.boot.autoconfigure.SpringBootApplication
 import org.springframework.boot.runApplication
+import org.springframework.stereotype.Component
 import picocli.CommandLine
 import picocli.CommandLine.IFactory
 import kotlin.system.exitProcess
 
 @SpringBootApplication
-class GitTallyApplication(
+class GitTallyApplication
+
+@Component
+class CliRunner(
     private val factory: IFactory,
     private val rootCommand: GitTallyCommand,
-) : CommandLineRunner {
+) : CommandLineRunner, ExitCodeGenerator {
+    private var exitCode = 0
+
     override fun run(vararg args: String) {
-        exitProcess(CommandLine(rootCommand, factory).execute(*args))
+        exitCode = CommandLine(rootCommand, factory).execute(*args)
     }
+
+    override fun getExitCode() = exitCode
 }
 
 fun main(args: Array<String>) {
-    runApplication<GitTallyApplication>(*args)
+    exitProcess(SpringApplication.exit(runApplication<GitTallyApplication>(*args)))
 }