Add 'Mad Lib' solution

README.md

@@ -7,7 +7,7 @@ Exercises for Programmers: 57 Challenges to Develop Your Coding Skills by Brian
 - Exercise 1. [Saying Hello](https://github.com/durimkryeziu/exercises-for-programmers-java/tree/main/saying-hello)
 - Exercise 2. [Counting the Number of Characters](https://github.com/durimkryeziu/exercises-for-programmers-java/tree/main/characters-count)
 - Exercise 3. [Printing Quotes](https://github.com/durimkryeziu/exercises-for-programmers-java/tree/main/printing-quotes)
-- Exercise 4. Mad Lib
+- Exercise 4. [Mad Lib](https://github.com/durimkryeziu/exercises-for-programmers-java/tree/main/mad-lib)
 - Exercise 5. Simple Math
 - Exercise 6. Retirement Calculator
 

mad-lib/build.gradle

@@ -0,0 +1,8 @@
+plugins {
+    id 'com.craftsmanshipinsoftware.common-conventions'
+}
+
+dependencies {
+    testImplementation(libs.assertj.core)
+    testImplementation(libs.junit.jupiter)
+}

mad-lib/src/main/java/com/craftsmanshipinsoftware/madlib/MadLib.java

@@ -0,0 +1,57 @@
+package com.craftsmanshipinsoftware.madlib;
+
+import java.io.InputStream;
+import java.io.PrintStream;
+import java.util.Objects;
+import java.util.Scanner;
+
+class MadLib {
+
+  private final InputStream inputStream;
+  private final PrintStream printStream;
+
+  MadLib(InputStream inputStream, PrintStream printStream) {
+    Objects.requireNonNull(inputStream, "inputStream cannot be null");
+    Objects.requireNonNull(printStream, "printStream cannot be null");
+    this.inputStream = inputStream;
+    this.printStream = printStream;
+  }
+
+  void printStory() {
+    try (Scanner scanner = new Scanner(inputStream)) {
+      String noun = promptForInput("Enter a noun: ", scanner);
+      if (noun == null) {
+        return;
+      }
+      String verb = promptForInput("Enter a verb: ", scanner);
+      if (verb == null) {
+        return;
+      }
+      String adjective = promptForInput("Enter an adjective: ", scanner);
+      if (adjective == null) {
+        return;
+      }
+      String adverb = promptForInput("Enter an adverb: ", scanner);
+      if (adverb == null) {
+        return;
+      }
+      this.printStream.println("Do you " + verb + " your " + adjective + " " + noun + " " + adverb + "? That's hilarious!");
+    }
+  }
+
+  @SuppressWarnings("PMD.SystemPrintln")
+  private String promptForInput(String prompt, Scanner scanner) {
+    System.out.print(prompt);
+    String input = readInput(scanner);
+    if (input == null || input.isBlank()) {
+      this.printStream.println("Please enter something as input!");
+      return null;
+    }
+    return input;
+  }
+
+  private String readInput(Scanner scanner) {
+    return scanner.hasNext() ? scanner.nextLine() : null;
+  }
+
+}

mad-lib/src/main/java/com/craftsmanshipinsoftware/madlib/Main.java

@@ -0,0 +1,9 @@
+package com.craftsmanshipinsoftware.madlib;
+
+public class Main {
+
+  public static void main(String[] args) {
+    MadLib madLib = new MadLib(System.in, System.out);
+    madLib.printStory();
+  }
+}

mad-lib/src/test/java/com/craftsmanshipinsoftware/madlib/MadLibTest.java

@@ -0,0 +1,31 @@
+package com.craftsmanshipinsoftware.madlib;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+class MadLibTest {
+
+  @ParameterizedTest(name = "Given input [{0}]")
+  @ValueSource(strings = {"", "dog", "dog\nwalk", "dog\nwalk\nblue"})
+  void printStory_GivenInputIsMissing_ShouldAskForMissingInput(String input) {
+    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+    MadLib madLib = new MadLib(new ByteArrayInputStream(input.getBytes()), new PrintStream(outputStream));
+    madLib.printStory();
+    assertThat(outputStream).hasToString("Please enter something as input!" + System.lineSeparator());
+  }
+
+  @Test
+  void printStory_GivenAllNeededInput_ShouldPrintStory() {
+    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+    MadLib madLib = new MadLib(new ByteArrayInputStream("dog\nwalk\nblue\nquickly".getBytes()), new PrintStream(outputStream));
+    madLib.printStory();
+    assertThat(outputStream).hasToString("Do you walk your blue dog quickly? That's hilarious!" + System.lineSeparator());
+  }
+
+}

settings.gradle

@@ -1,2 +1,2 @@
 rootProject.name = 'exercises-for-programmers-java'
-include('saying-hello', 'characters-count', 'printing-quotes')
+include('saying-hello', 'characters-count', 'printing-quotes', 'mad-lib')