test: fix cylinder surface area formula

Replaces erroneous volume calculation with correct surface area

Author: Genyus

README.md

@@ -195,15 +195,15 @@ Inside the `com.cbfacademy.shapes` package under the `shapes` module, create an
 
 In the same package, create a concrete class `Sphere` that extends `Shape`:
 - `Sphere(double radius)` - constructor
-- `double getArea()` - overrides the base method. The value is given by the formula (`4` * `𝛑` * (`radius`<sup>2</sup>))
+- `double getArea()` - overrides the base method. The value is given by the formula: `4 * 𝛑 * (radius^2)` (where `radius^2` = radius<sup>2</sup>)
 
 In the same package, create a concrete class `Rectangle` that extends `Shape`:
 - `Rectangle(double length, double width)` - constructor
-- `double getArea()` - overrides the base method. The value is given by the formula (`length` * `width`)
+- `double getArea()` - overrides the base method. The value is given by the formula: `length * width`
 
 In the same package, create a concrete class `Cylinder` that extends `Shape`:
 - `Cylinder(double radius, double height)` - constructor
-- `double getArea()` - overrides the base method. The value is given by the formula (`height` * `𝛑` * (`radius`<sup>2</sup>)).
+- `double getArea()` - overrides the base method. The value is given by the formula: `2 * 𝛑 * radius * (height + radius)`.
 
 #### :information_source: Notes
 Consider the appropriate visibility of all constructors, methods and instance variables

shapes/src/test/java/com/cbfacademy/shapes/ShapeTest.java

@@ -42,7 +42,7 @@ private static Stream<Arguments> getArea_CalculatesAreaCorrectly() {
         for (Shape shape : shapeArray) {
             switch (shape.getClass().getSimpleName()) {
                 case "Cylinder":
-                    area = cylinderHeight * Math.PI * Math.pow(cylinderRadius, 2);
+                    area = (cylinderHeight + cylinderRadius) * 2 * Math.PI * cylinderRadius;
                     break;
                 case "Rectangle":
                     area = rectangleLength * rectangleWidth;