solution of homework2

build.gradle

@@ -2,6 +2,10 @@ plugins {
     id 'org.jetbrains.kotlin.jvm' version '1.7.21'
 }
 
+test {
+    useJUnitPlatform()
+}
+
 group 'ru.otus'
 version '1.0-SNAPSHOT'
 
@@ -11,4 +15,5 @@ repositories {
 
 dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib"
+    testImplementation "org.junit.jupiter:junit-jupiter:5.8.1"
 }

src/main/kotlin/ru/otus/homework/builder.kt

@@ -0,0 +1,38 @@
+package ru.otus.homework
+
+class Notification private constructor(
+  val iconRes: String?,
+  val title: String,
+  val subTitle: String?,
+) {
+  data class Builder(
+    var iconRes: String? = null,
+    var title: String? = null,
+    var subTitle: String? = null,
+  ) {
+    fun iconRes(iconRes: String) = apply {
+      this.iconRes = iconRes
+    }
+    fun title(title: String) = apply {
+      this.title = title
+    }
+    fun subTitle(subTitle: String) = apply {
+      this.subTitle = subTitle
+    }
+
+    fun build() = Notification(
+      iconRes = iconRes,
+      title = title ?: "",
+      subTitle = subTitle
+    )
+  }
+}
+
+fun main() {
+  val notification = Notification.Builder()
+    .title("test notification title")
+    .subTitle("test notification subtitle")
+    .build()
+
+  println("Result notification iconRes: ${notification.iconRes}, title: ${notification.title}, subTitle: ${notification.subTitle}")
+}

src/main/kotlin/ru/otus/homework/command.kt

@@ -0,0 +1,66 @@
+package ru.otus.homework
+
+interface Command {
+  fun execute()
+  fun undo()
+}
+
+data class Clipboard(var content: String = "")
+
+class Editor(initialContent: String) {
+  private var content = initialContent
+
+  fun write(text: String) {
+    content += text
+  }
+
+  fun remove(text: String) {
+    content = content.removeSuffix(text)
+  }
+
+  fun read(): String = content
+}
+
+class PasteCommand(
+  private val editor: Editor,
+  private val clipboard: Clipboard,
+) : Command {
+  override fun execute() {
+    editor.write(clipboard.content)
+  }
+
+  override fun undo() {
+    editor.remove(clipboard.content)
+  }
+}
+
+class EditorInvoker {
+  private val commandsCache = mutableListOf<Command>()
+
+  fun executeCommand(command: Command) {
+    commandsCache.add(command)
+    command.execute()
+  }
+
+  fun undoLastCommand() {
+    if (commandsCache.isNotEmpty()) {
+      commandsCache.removeLast().undo()
+    }
+  }
+}
+
+fun main() {
+  val editor = Editor("artem")
+  val invoker = EditorInvoker()
+
+  println("initial editor: ${editor.read()}")
+
+  invoker.executeCommand(PasteCommand(editor, Clipboard("test")))
+  invoker.executeCommand(PasteCommand(editor, Clipboard("boo")))
+
+  println("after paste: ${editor.read()}")
+
+  invoker.undoLastCommand()
+
+  println("after undo: ${editor.read()}")
+}

src/main/kotlin/ru/otus/homework/decorator.kt

@@ -0,0 +1,31 @@
+package ru.otus.homework
+
+interface Logger {
+  fun log(text: String)
+}
+
+class PrintLogger : Logger {
+  override fun log(text: String) {
+    println(text)
+  }
+}
+
+class MapLoggerDecorator<K, V>(
+  private val map: MutableMap<K, V> = mutableMapOf(),
+  private val logger: Logger,
+): MutableMap<K, V> by map {
+  override fun put(key: K, value: V): V? {
+    return map.put(key, value).apply {
+      logger.log("MapLoggerDecorator putted key: $key, value: $value. Result map: $map")
+    }
+  }
+}
+
+fun main() {
+  val mapLoggerDecorator = MapLoggerDecorator<String, String>(
+    logger = PrintLogger(),
+  )
+  mapLoggerDecorator["artem"] = "tim"
+  mapLoggerDecorator["andrey"] = "drew"
+  mapLoggerDecorator["alexei"] = "alex"
+}

src/main/kotlin/ru/otus/homework/singleton.kt

@@ -0,0 +1,21 @@
+package ru.otus.homework
+
+class Singleton private constructor() {
+  companion object {
+    val instance: Singleton by lazy {
+      Singleton()
+    }
+  }
+
+  private var i = 0
+
+  fun doSomething() = ++i
+}
+
+fun main() {
+  val instance1 = Singleton.instance
+  println("instance1 increment: ${instance1.doSomething()}")
+
+  val instance2 = Singleton.instance
+  println("instance2 increment: ${instance2.doSomething()}")
+}

src/test/kotlin/ru/otus/homework/BuilderTest.kt

@@ -0,0 +1,38 @@
+package ru.otus.homework
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertNull
+import org.junit.jupiter.api.Test
+
+private const val notificationTitle = "test notification title"
+private const val notificationSubTitle = "test notification subtitle"
+
+class BuilderTest {
+  private companion object {
+    val notification = Notification.Builder()
+      .title(notificationTitle)
+      .subTitle(notificationSubTitle)
+      .build()
+  }
+
+  @Test
+  fun notificationIconRes() {
+    assertNull(notification.iconRes)
+  }
+
+  @Test
+  fun notificationTitle() {
+    assertEquals(
+      notificationTitle,
+      notification.title
+    )
+  }
+
+  @Test
+  fun notificationSubTitle() {
+    assertEquals(
+      notificationSubTitle,
+      notification.subTitle
+    )
+  }
+}

src/test/kotlin/ru/otus/homework/CommandTest.kt

@@ -0,0 +1,61 @@
+package ru.otus.homework
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.MethodOrderer
+import org.junit.jupiter.api.Order
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.TestMethodOrder
+
+private const val initialEditorContent = "artem"
+private const val clipboardFirstContent = "test"
+private const val clipboardSecondContent = "boo"
+
+@TestMethodOrder(MethodOrderer.OrderAnnotation::class)
+class CommandTest {
+  private companion object {
+    private val editor: Editor = Editor(initialEditorContent)
+    private val invoker = EditorInvoker()
+  }
+
+  @Test
+  @Order(1)
+  fun shouldInitialValue() {
+    assertEquals(
+      initialEditorContent,
+      editor.read()
+    )
+  }
+
+  @Test
+  @Order(2)
+  fun shouldPasteFirst() {
+    invoker.executeCommand(PasteCommand(editor, Clipboard(clipboardFirstContent)))
+
+    assertEquals(
+      "$initialEditorContent$clipboardFirstContent",
+      editor.read()
+    )
+  }
+
+  @Test
+  @Order(3)
+  fun shouldPasteSecond() {
+    invoker.executeCommand(PasteCommand(editor, Clipboard(clipboardSecondContent)))
+
+    assertEquals(
+      "$initialEditorContent$clipboardFirstContent$clipboardSecondContent",
+      editor.read()
+    )
+  }
+
+  @Test
+  @Order(4)
+  fun shouldLastCommandUndo() {
+    invoker.undoLastCommand()
+
+    assertEquals(
+      "$initialEditorContent$clipboardFirstContent",
+      editor.read()
+    )
+  }
+}

src/test/kotlin/ru/otus/homework/SingletonTest.kt

@@ -0,0 +1,33 @@
+package ru.otus.homework
+
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.ClassOrderer.OrderAnnotation
+import org.junit.jupiter.api.MethodOrderer
+import org.junit.jupiter.api.Order
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.TestMethodOrder
+
+@TestMethodOrder(MethodOrderer.OrderAnnotation::class)
+class SingletonTest {
+  @Test
+  @Order(1)
+  fun instance1Increment() {
+    val instance1: Singleton = Singleton.instance
+
+    assertEquals(
+      1,
+      instance1.doSomething()
+    )
+  }
+
+  @Test
+  @Order(2)
+  fun instance2Increment() {
+    val instance2: Singleton = Singleton.instance
+
+    assertEquals(
+      2,
+      instance2.doSomething()
+    )
+  }
+}