Finished product tests

Author: fracz

src/main/java/pl/edu/agh/mwo/invoice/Demo.java

@@ -1,7 +1,10 @@
 package pl.edu.agh.mwo.invoice;
 
 public class Demo {
+    public static final String SDLKFJSDKJFLKSDJFLK = "";
+
     public static void main(String[] args) {
-        System.out.println(0.1 + 0.2);
+//        System.out.println(0.1 + 0.2);
+        System.out.println(" ".trim().isEmpty());
     }
 }

src/main/java/pl/edu/agh/mwo/invoice/product/Product.java

@@ -1,5 +1,6 @@
 package pl.edu.agh.mwo.invoice.product;
 
+import java.io.IOException;
 import java.math.BigDecimal;
 
 public abstract class Product {
@@ -10,6 +11,12 @@ public abstract class Product {
     private final BigDecimal taxPercent;
 
     protected Product(String name, BigDecimal price, BigDecimal tax) {
+        if (name == null || name.equals("")) {
+            throw new IllegalArgumentException("Product name cannot be null.");
+        }
+        if (price == null || price.compareTo(BigDecimal.ZERO) == -1) {
+            throw new IllegalArgumentException("Price of the product cannot be null or negative.");
+        }
         this.name = name;
         this.price = price;
         this.taxPercent = tax;