Add Order tests

src/test/java/OrderTest.java

@@ -0,0 +1,92 @@
+import org.example.Constants;
+import org.example.Order;
+import org.example.Product;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class OrderTest {
+
+    private static final float DELTA = 0.0001f;
+
+    @Test
+    void calculateTotalPrice() {
+        Product product = new Product(1, "Produkt 1", 0.5f, 100f, Constants.lowVat);
+        Order order = new Order(List.of(product));
+
+        assertEquals(100f, order.calculateTotalPrice(), DELTA);
+    }
+
+    @Test
+    void calculateTotalVat() {
+        Product product = new Product(1, "Produkt 1", 0.5f, 100f, Constants.lowVat);
+        Order order = new Order(List.of(product));
+
+        float expectedVat = 100f * Constants.lowVat + order.calculateShippingVat(List.of(product));
+        assertEquals(expectedVat, order.calculateTotalVat(), DELTA);
+    }
+
+    @Test
+    void calculateShippingCost() {
+        Product product = new Product(1, "Produkt 1", 0.05f, 60f, Constants.highVat);
+        Order order = new Order(List.of(product));
+
+        assertEquals(3.95f, order.calculateShippingCost(), DELTA);
+    }
+
+    @Test
+    void calculateShippingCostForExpensiveOrder() {
+        Product product = new Product(1, "Produkt 1", 2.69f, 5000f, Constants.highVat);
+        Order order = new Order(List.of(product));
+
+        assertEquals(0f, order.calculateShippingCost(), DELTA);
+    }
+
+    @Test
+    void calculateTotalPriceWithVat() {
+        Product product1 = new Product(1, "Produkt 1", 0.5f, 200f, Constants.highVat);
+        Product product2 = new Product(1, "Produkt 2", 0.5f, 200f, Constants.lowVat);
+        List<Product> products = List.of(product1, product2);
+        Order order = new Order(products);
+
+        float expectedTotal = 200f + (200f * Constants.highVat)
+                + 200f + (200f * Constants.lowVat)
+                + 4.95f + order.calculateShippingVat(products);
+
+        assertEquals(expectedTotal, order.calculateTotalPriceWithVat(), DELTA);
+    }
+
+    @Test
+    void calculateShippingVat() {
+        Product lowVatProduct = new Product(1, "Produkt 1", 1.0f, 100f, Constants.lowVat);
+        Product highVatProduct = new Product(2, "Produkt 2", 1.0f, 300f, Constants.highVat);
+
+        List<Product> products = List.of(lowVatProduct, highVatProduct);
+
+        Order order = new Order(List.of(lowVatProduct, highVatProduct));
+
+        float shippingCost = order.calculateShippingCost();
+        float totalPrice = 400f;
+
+        float lowVatPortion = 100f / totalPrice;
+        float highVatPortion = 300f / totalPrice;
+
+        float expectedShippingVat = shippingCost
+                - (shippingCost * lowVatPortion / (1 + Constants.lowVat)
+                + shippingCost * highVatPortion / (1 + Constants.highVat));
+
+        assertEquals(expectedShippingVat, order.calculateShippingVat(products), DELTA);
+    }
+
+    @Test
+    void calculateTotalPriceForMultipleProducts() {
+        Product product1 = new Product(1, "Produkt 1", 1f, 100f, Constants.lowVat);
+        Product product2 = new Product(2, "Produkt 2", 2f, 200f, Constants.highVat);
+
+        Order order = new Order(List.of(product1, product2));
+
+        assertEquals(300f, order.calculateTotalPrice(), DELTA);
+    }
+}