diff --git a/domain-model.md b/domain-model.md
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+++ b/domain-model.md
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+## Domain model Product class
+| Variables      | Methods             | Scenario           | Outputs                         |
+|----------------|---------------------|--------------------|---------------------------------|
+| int fullPrice  |                     |                    |                                 | 
+| float discount |                     |                    |                                 |
+| String name    |                     |                    |                                 |
+|                | `int getCost()`     | Method gets called | positive integer or 0           |
+|                | `String toString()` | Method gets called | Detailed information about item | 
+
+## Domain model CheckoutMachine class:
+| Variables              | Methods                                          | Scenario              | Output                                           |
+|------------------------|--------------------------------------------------|-----------------------|--------------------------------------------------|
+| `List<Product> basket` |                                                  |                       |                                                  |
+|                        | `void addProduct(Product product)`               | User adds product     | Adds a single product to the basket              |
+|                        | `void addProduct(Product product, int count)`    | User adds products    | Adds how ever many products specified in call    |
+|                        |                                                  |                       |                                                  |
+|                        | `void removeProduct(Product product)`            | User removes product  | Removes a single product from the basket         |
+|                        | `void removeProduct(Product product, int count)` | User removes products | Removes how ever many products specified in call |
+|                        |                                                  |                       |                                                  |
+|                        | `boolean processPayment()`                       | Payment failed        | false, display some error message                |
+|                        |                                                  | Payment succeeded     | true, display some error message                 |
+|                        | `private void printReceipt()`                    | Method gets called    | Prints receipt to customer                       |
diff --git a/src/main/java/com/booleanuk/core/Basket.java b/src/main/java/com/booleanuk/core/Basket.java
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+++ b/src/main/java/com/booleanuk/core/Basket.java
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+package com.booleanuk.core;
+
+import java.util.HashMap;
+
+public class Basket {
+    public HashMap<String, Integer> items = new HashMap<>();
+
+    public void add(String product, int price) {
+        this.items.put(product, price);
+    }
+
+    public float total() {
+        int price = 0;
+        for (int p : this.items.values())
+            price += p;
+
+        return price;
+    }
+}
diff --git a/src/main/java/com/booleanuk/core/Product.java b/src/main/java/com/booleanuk/core/Product.java
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+++ b/src/main/java/com/booleanuk/core/Product.java
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+package com.booleanuk.core;
+
+public class Product {
+    public String name;
+    public int fullPriceInNOK;
+    public float discount; // 0..1, 0 means no discount 1 means 100%
+
+    public Product(String name, int fullPriceInNOK, float discount) {
+        this.name = name;
+        this.fullPriceInNOK = fullPriceInNOK;
+        this.discount = discount;
+    }
+
+    public float price() {
+        return this.fullPriceInNOK * (1 - discount);
+    }
+}
diff --git a/src/test/java/com/booleanuk/core/BasketTest.java b/src/test/java/com/booleanuk/core/BasketTest.java
new file mode 100644
index 0000000..3b78638
--- /dev/null
+++ b/src/test/java/com/booleanuk/core/BasketTest.java
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+package com.booleanuk.core;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+class BasketTest {
+    @Test
+    public void testAddProductToBasket() {
+        Basket basket = new Basket();
+        basket.add("Bread", 29);
+        Assertions.assertEquals(1, basket.items.size());
+    }
+
+    @Test
+    public void testCalculateTotal() {
+        Basket basket = new Basket();
+        basket.add("Bread", 29);
+        basket.add("Soda", 20);
+
+        Assertions.assertEquals(2, basket.items.size());
+        Assertions.assertEquals(29 + 20, basket.total());
+
+        basket.add("Milk", 25);
+    }
+
+}
diff --git a/src/test/java/com/booleanuk/core/ProductTest.java b/src/test/java/com/booleanuk/core/ProductTest.java
new file mode 100644
index 0000000..d34a496
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+++ b/src/test/java/com/booleanuk/core/ProductTest.java
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+package com.booleanuk.core;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+class ProductTest {
+    @Test
+    public void shouldInstantiateCorrectly() {
+        Product product = new Product("Bread", 29, 0.0f);
+        Assertions.assertEquals("Bread", product.name);
+        Assertions.assertEquals(29, product.fullPriceInNOK);
+        Assertions.assertEquals(0.0f, product.discount);
+    }
+
+    @Test
+    public void shouldCalculatePrice() {
+        Product product = new Product("Bread", 29, 0.0f);
+        Assertions.assertEquals(29, product.price());
+    }
+}