feat: kata/classy-extentions

kata/8-kyu/classy-extentions/README.md

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+# [Classy Extentions](https://www.codewars.com/kata/classy-extentions "https://www.codewars.com/kata/55a14aa4817efe41c20000bc")
+
+The goal of this kata is to train the basic OOP concepts of inheritance and method overriding.
+
+You will be preloaded with the `Animal` class, so you should only edit the `Cat` class.
+
+### Task
+
+Your task is to complete the `Cat` class which extends `Animal` and replace the `speak` method to return the cats name + meows.
+e.g. `'Mr Whiskers meows.'`
+
+The name attribute is accessible in the class with `this.name`.
+
+Reference: [Oracle docs](https://docs.oracle.com/javase/tutorial/java/IandI/subclasses.html)

kata/8-kyu/classy-extentions/main/Animal.java

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+class Animal {
+  protected final String name;
+
+  Animal(String name) {
+    this.name = name;
+  }
+
+  public String speak() {
+    return this.name + " makes a noise.";
+  }
+}

kata/8-kyu/classy-extentions/main/Cat.java

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+class Cat extends Animal {
+  Cat(String name) {
+    super(name);
+  }
+
+  @Override
+  public String speak() {
+    return "%s meows.".formatted(this.name);
+  }
+}

kata/8-kyu/classy-extentions/test/SampleTest.java

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+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
+
+import org.junit.jupiter.api.Test;
+
+class SampleTest {
+  @Test
+  void wildBoar() {
+    Animal animal = new Animal("Wild Boar");
+    assertEquals("Wild Boar makes a noise.", animal.speak());
+  }
+
+  @Test
+  void mrWhiskers() {
+    Cat cat = new Cat("Mr Whiskers");
+    assertEquals("Mr Whiskers meows.", cat.speak());
+    assertInstanceOf(Animal.class, cat);
+  }
+
+  @Test
+  void lamp() {
+    Cat cat = new Cat("Lamp");
+    assertEquals("Lamp meows.", cat.speak());
+  }
+
+  @Test
+  void moneyBags() {
+    Cat cat = new Cat("$$Money Bags$$");
+    assertEquals("$$Money Bags$$ meows.", cat.speak());
+  }
+}

kata/8-kyu/index.md

@@ -31,6 +31,7 @@
 - [Century From Year](century-from-year "5a3fe3dde1ce0e8ed6000097")
 - [Circles in Polygons](circles-in-polygons "5a026a9cffe75fbace00007f")
 - [Classic Hello World](classic-hello-world "57036f007fd72e3b77000023")
+- [Classy Extentions](classy-extentions "55a14aa4817efe41c20000bc")
 - [Closest elevator](closest-elevator "5c374b346a5d0f77af500a5a")
 - [Collatz Conjecture (3n+1)](collatz-conjecture-3n-plus-1 "577a6e90d48e51c55e000217")
 - [Collinearity](collinearity "65ba420888906c1f86e1e680")