diff --git a/src/main/java/edu/ntnu/idi/idatt2003/g40/mappe/Exchange.java b/src/main/java/edu/ntnu/idi/idatt2003/g40/mappe/Exchange.java
index 9cbccbf..6276925 100644
--- a/src/main/java/edu/ntnu/idi/idatt2003/g40/mappe/Exchange.java
+++ b/src/main/java/edu/ntnu/idi/idatt2003/g40/mappe/Exchange.java
@@ -55,11 +55,13 @@ public Transaction buy(String symbol, BigDecimal quantity, Player player) {
         Stock stock = stockMap.get(symbol);
         Share share = new Share(stock, quantity, stock.getSalesPrice());
         TransactionCalculator calculator = new PurchaseCalculator(share);
+        player.withdrawMoney(calculator.calculateTotal());
         return new Purchase(share, week, calculator);
     }
 
     public Transaction sell(Share share, Player player) {
         TransactionCalculator calculator = new SaleCalculator(share);
+        player.addMoney(calculator.calculateTotal());
         return new Sale(share, week, calculator);
     }
 
diff --git a/src/main/java/edu/ntnu/idi/idatt2003/g40/mappe/Player.java b/src/main/java/edu/ntnu/idi/idatt2003/g40/mappe/Player.java
index 0114bbf..0d5939d 100644
--- a/src/main/java/edu/ntnu/idi/idatt2003/g40/mappe/Player.java
+++ b/src/main/java/edu/ntnu/idi/idatt2003/g40/mappe/Player.java
@@ -1,7 +1,6 @@
 package edu.ntnu.idi.idatt2003.g40.mappe;
 
 import java.math.BigDecimal;
-import java.util.Objects;
 
 public class Player {
 
diff --git a/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/ExchangeTest.java b/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/ExchangeTest.java
index a06f463..9e11d44 100644
--- a/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/ExchangeTest.java
+++ b/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/ExchangeTest.java
@@ -1,3 +1,92 @@
-public class ExchangeTest {
-    
-}
+package edu.ntnu.idi.idatt2003.g40.mappe;
+
+import org.junit.jupiter.api.Test;
+
+import java.math.BigDecimal;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class ExchangeTest {
+
+    @Test
+    void constructorSetsNameWeekAndStocksCorrectly() {
+        Stock apple = new Stock("AAPL", "Apple", new BigDecimal("150"));
+        Stock tesla = new Stock("TSLA", "Tesla", new BigDecimal("200"));
+
+        Exchange exchange = new Exchange("NASDAQ", List.of(apple, tesla));
+
+        assertEquals("NASDAQ", exchange.getName());
+        assertEquals(1, exchange.getWeek());
+        assertTrue(exchange.hasStock("AAPL"));
+        assertTrue(exchange.hasStock("TSLA"));
+    }
+
+    @Test
+    void getStockReturnsCorrectStock() {
+        Stock apple = new Stock("AAPL", "Apple", new BigDecimal("150"));
+        Exchange exchange = new Exchange("NASDAQ", List.of(apple));
+
+        Stock result = exchange.getStock("AAPL");
+
+        assertSame(apple, result);
+    }
+
+    @Test
+    void findStocksReturnsMatchingStocksBySymbolOrCompany() {
+        Stock apple = new Stock("AAPL", "Apple", new BigDecimal("150"));
+        Stock tesla = new Stock("TSLA", "Tesla", new BigDecimal("200"));
+        Exchange exchange = new Exchange("NASDAQ", List.of(apple, tesla));
+
+        List<Stock> resultBySymbol = exchange.findStocks("AAP");
+        List<Stock> resultByCompany = exchange.findStocks("tes");
+
+        assertEquals(1, resultBySymbol.size());
+        assertTrue(resultBySymbol.contains(apple));
+
+        assertEquals(1, resultByCompany.size());
+        assertTrue(resultByCompany.contains(tesla));
+    }
+
+    @Test
+    void buyReturnsPurchaseAndWithdrawsMoneyFromPlayer() {
+        Stock apple = new Stock("AAPL", "Apple", new BigDecimal("100"));
+        Exchange exchange = new Exchange("NASDAQ", List.of(apple));
+        Player player = new Player("Alice", new BigDecimal("1000"));
+
+        Transaction transaction = exchange.buy("AAPL", new BigDecimal("2"), player);
+
+        assertInstanceOf(Purchase.class, transaction);
+        assertEquals(1, transaction.getWeek());
+        assertEquals(new BigDecimal("2"), transaction.getShare().getQuantity());
+        assertEquals(new BigDecimal("100"), transaction.getShare().getPurchasePrice());
+        assertEquals(new BigDecimal("799.000"), player.getMoney());
+    }
+
+    @Test
+    void sellReturnsSaleAndAddsMoneyToPlayer() {
+        Stock apple = new Stock("AAPL", "Apple", new BigDecimal("150"));
+        Exchange exchange = new Exchange("NASDAQ", List.of(apple));
+        Player player = new Player("Alice", new BigDecimal("1000"));
+        Share share = new Share(apple, new BigDecimal("2"), new BigDecimal("100"));
+
+        Transaction transaction = exchange.sell(share, player);
+
+        assertInstanceOf(Sale.class, transaction);
+        assertEquals(1, transaction.getWeek());
+        assertSame(share, transaction.getShare());
+        assertEquals(new BigDecimal("1267.9000"), player.getMoney());
+    }
+
+    @Test
+    void advanceIncreasesWeekAndUpdatesStockPrice() {
+        Stock apple = new Stock("AAPL", "Apple", new BigDecimal("100"));
+        Exchange exchange = new Exchange("NASDAQ", List.of(apple));
+
+        BigDecimal oldPrice = apple.getSalesPrice();
+        exchange.advance();
+
+        assertEquals(2, exchange.getWeek());
+        assertNotEquals(oldPrice, apple.getSalesPrice());
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/PlayerTest.java b/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/PlayerTest.java
index e3c1316..f62c0d5 100644
--- a/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/PlayerTest.java
+++ b/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/PlayerTest.java
@@ -1,3 +1,48 @@
-public class PlayerTest {
-    
-}
+package edu.ntnu.idi.idatt2003.g40.mappe;
+
+import org.junit.jupiter.api.Test;
+
+import java.math.BigDecimal;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class PlayerTest {
+
+    @Test
+    void constructorSetsNameMoneyPortfolioAndArchive() {
+        Player player = new Player("Alice", new BigDecimal("1000"));
+
+        assertEquals("Alice", player.getName());
+        assertEquals(new BigDecimal("1000"), player.getMoney());
+        assertNotNull(player.getPortfolio());
+        assertNotNull(player.getTransactionArchive());
+    }
+
+    @Test
+    void addMoneyIncreasesBalance() {
+        Player player = new Player("Bob", new BigDecimal("500"));
+
+        player.addMoney(new BigDecimal("200"));
+
+        assertEquals(new BigDecimal("700"), player.getMoney());
+    }
+
+    @Test
+    void withdrawMoneyDecreasesBalance() {
+        Player player = new Player("Charlie", new BigDecimal("500"));
+
+        player.withdrawMoney(new BigDecimal("150"));
+
+        assertEquals(new BigDecimal("350"), player.getMoney());
+    }
+
+    @Test
+    void addAndWithdrawMoneyUpdateBalanceCorrectly() {
+        Player player = new Player("Dana", new BigDecimal("1000"));
+
+        player.addMoney(new BigDecimal("250"));
+        player.withdrawMoney(new BigDecimal("300"));
+
+        assertEquals(new BigDecimal("950"), player.getMoney());
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/PortfolioTest.java b/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/PortfolioTest.java
index 3518005..c8a5e3a 100644
--- a/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/PortfolioTest.java
+++ b/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/PortfolioTest.java
@@ -1,3 +1,80 @@
-public class PortfolioTest {
-    
-}
+package edu.ntnu.idi.idatt2003.g40.mappe;
+
+import org.junit.jupiter.api.Test;
+
+import java.math.BigDecimal;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class PortfolioTest {
+
+    @Test
+    void addShareAddsShareToPortfolio() {
+        Portfolio portfolio = new Portfolio();
+        Stock stock = new Stock("AAPL", "Apple", new BigDecimal("150"));
+        Share share = new Share(stock, new BigDecimal("2"), new BigDecimal("100"));
+
+        boolean result = portfolio.addShare(share);
+
+        assertTrue(result);
+        assertTrue(portfolio.contains(share));
+    }
+
+    @Test
+    void removeShareRemovesShareFromPortfolio() {
+        Portfolio portfolio = new Portfolio();
+        Stock stock = new Stock("TSLA", "Tesla", new BigDecimal("200"));
+        Share share = new Share(stock, new BigDecimal("1"), new BigDecimal("200"));
+
+        portfolio.addShare(share);
+        boolean result = portfolio.removeShare(share);
+
+        assertTrue(result);
+        assertFalse(portfolio.contains(share));
+    }
+
+    @Test
+    void getSharesReturnsAllShares() {
+        Portfolio portfolio = new Portfolio();
+
+        Stock stock = new Stock("AAPL", "Apple", new BigDecimal("150"));
+        Share share = new Share(stock, new BigDecimal("3"), new BigDecimal("150"));
+
+        portfolio.addShare(share);
+
+        List<Share> shares = portfolio.getShares();
+
+        assertEquals(1, shares.size());
+        assertTrue(shares.contains(share));
+    }
+
+    @Test
+    void getSharesWithSymbolReturnsMatchingShares() {
+        Portfolio portfolio = new Portfolio();
+
+        Stock apple = new Stock("AAPL", "Apple", new BigDecimal("150"));
+        Stock tesla = new Stock("TSLA", "Tesla", new BigDecimal("200"));
+
+        Share appleShare = new Share(apple, new BigDecimal("1"), new BigDecimal("150"));
+        Share teslaShare = new Share(tesla, new BigDecimal("1"), new BigDecimal("200"));
+
+        portfolio.addShare(appleShare);
+        portfolio.addShare(teslaShare);
+
+        List<Share> result = portfolio.getShares("AAPL");
+
+        assertEquals(1, result.size());
+        assertTrue(result.contains(appleShare));
+    }
+
+    @Test
+    void containsReturnsFalseWhenShareNotPresent() {
+        Portfolio portfolio = new Portfolio();
+
+        Stock stock = new Stock("NVDA", "Nvidia", new BigDecimal("800"));
+        Share share = new Share(stock, new BigDecimal("1"), new BigDecimal("800"));
+
+        assertFalse(portfolio.contains(share));
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/PurchaseCalculatorTest.java b/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/PurchaseCalculatorTest.java
index 6737cf2..4c73305 100644
--- a/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/PurchaseCalculatorTest.java
+++ b/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/PurchaseCalculatorTest.java
@@ -1,3 +1,45 @@
-public class PurchaseCalculatorTest {
-    
+package edu.ntnu.idi.idatt2003.g40.mappe;
+
+import org.junit.jupiter.api.Test;
+import java.math.BigDecimal;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class PurchaseCalculatorTest {
+
+    @Test
+    void calculateGrossReturnsPurchasePriceTimesQuantity() {
+        Stock stock = new Stock("AAPL", "Apple", new BigDecimal("150"));
+        Share share = new Share(stock, new BigDecimal("2"), new BigDecimal("100"));
+        PurchaseCalculator calculator = new PurchaseCalculator(share);
+
+        assertEquals(new BigDecimal("200"), calculator.calculateGross());
+    }
+
+    @Test
+    void calculateCommissionReturnsHalfPercentOfGross() {
+        Stock stock = new Stock("AAPL", "Apple", new BigDecimal("150"));
+        Share share = new Share(stock, new BigDecimal("2"), new BigDecimal("100"));
+        PurchaseCalculator calculator = new PurchaseCalculator(share);
+
+        assertEquals(new BigDecimal("1.000"), calculator.calculateCommission());
+    }
+
+    @Test
+    void calculateTaxReturnsZero() {
+        Stock stock = new Stock("AAPL", "Apple", new BigDecimal("150"));
+        Share share = new Share(stock, new BigDecimal("2"), new BigDecimal("100"));
+        PurchaseCalculator calculator = new PurchaseCalculator(share);
+
+        assertEquals(BigDecimal.ZERO, calculator.calculateTax());
+    }
+
+    @Test
+    void calculateTotalReturnsGrossPlusCommission() {
+        Stock stock = new Stock("AAPL", "Apple", new BigDecimal("150"));
+        Share share = new Share(stock, new BigDecimal("2"), new BigDecimal("100"));
+        PurchaseCalculator calculator = new PurchaseCalculator(share);
+
+        assertEquals(new BigDecimal("201.000"), calculator.calculateTotal());
+    }
 }
diff --git a/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/SaleCalculatorTest.java b/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/SaleCalculatorTest.java
index 5422865..3b7a0c6 100644
--- a/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/SaleCalculatorTest.java
+++ b/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/SaleCalculatorTest.java
@@ -1,3 +1,55 @@
-public class SaleCalculatorTest {
-    
-}
+package edu.ntnu.idi.idatt2003.g40.mappe;
+
+import org.junit.jupiter.api.Test;
+
+import java.math.BigDecimal;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class SaleCalculatorTest {
+
+    @Test
+    void calculateGrossReturnsSalesPriceTimesQuantity() {
+        Stock stock = new Stock("AAPL", "Apple", new BigDecimal("150"));
+        Share share = new Share(stock, new BigDecimal("2"), new BigDecimal("100"));
+        SaleCalculator calculator = new SaleCalculator(share);
+
+        assertEquals(new BigDecimal("300"), calculator.calculateGross());
+    }
+
+    @Test
+    void calculateCommissionReturnsOnePercentOfGross() {
+        Stock stock = new Stock("AAPL", "Apple", new BigDecimal("150"));
+        Share share = new Share(stock, new BigDecimal("2"), new BigDecimal("100"));
+        SaleCalculator calculator = new SaleCalculator(share);
+
+        assertEquals(new BigDecimal("3.00"), calculator.calculateCommission());
+    }
+
+    @Test
+    void calculateTaxReturnsThirtyPercentOfProfitWhenProfitIsPositive() {
+        Stock stock = new Stock("AAPL", "Apple", new BigDecimal("150"));
+        Share share = new Share(stock, new BigDecimal("2"), new BigDecimal("100"));
+        SaleCalculator calculator = new SaleCalculator(share);
+
+        assertEquals(new BigDecimal("29.1000"), calculator.calculateTax());
+    }
+
+    @Test
+    void calculateTaxReturnsZeroWhenProfitIsZeroOrNegative() {
+        Stock stock = new Stock("AAPL", "Apple", new BigDecimal("90"));
+        Share share = new Share(stock, new BigDecimal("2"), new BigDecimal("100"));
+        SaleCalculator calculator = new SaleCalculator(share);
+
+        assertEquals(BigDecimal.ZERO, calculator.calculateTax());
+    }
+
+    @Test
+    void calculateTotalReturnsGrossMinusCommissionMinusTax() {
+        Stock stock = new Stock("AAPL", "Apple", new BigDecimal("150"));
+        Share share = new Share(stock, new BigDecimal("2"), new BigDecimal("100"));
+        SaleCalculator calculator = new SaleCalculator(share);
+
+        assertEquals(new BigDecimal("267.9000"), calculator.calculateTotal());
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/ShareTest.java b/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/ShareTest.java
index 2e94fdf..0a5deb1 100644
--- a/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/ShareTest.java
+++ b/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/ShareTest.java
@@ -1,3 +1,48 @@
-public class ShareTest {
-    
-}
+package edu.ntnu.idi.idatt2003.g40.mappe;
+
+import org.junit.jupiter.api.Test;
+
+import java.math.BigDecimal;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertSame;
+
+class ShareTest {
+
+    @Test
+    void constructorStoresAllValuesCorrectly() {
+        Stock stock = new Stock("AAPL", "Apple Inc.", new BigDecimal("150.00"));
+        BigDecimal quantity = new BigDecimal("10");
+        BigDecimal purchasePrice = new BigDecimal("145.50");
+
+        Share share = new Share(stock, quantity, purchasePrice);
+
+        assertSame(stock, share.getStock());
+        assertEquals(quantity, share.getQuantity());
+        assertEquals(purchasePrice, share.getPurchasePrice());
+    }
+
+    @Test
+    void shareSupportsDecimalValues() {
+        Stock stock = new Stock("TSLA", "Tesla Inc.", new BigDecimal("200.00"));
+
+        Share share = new Share(
+                stock,
+                new BigDecimal("2.5"),
+                new BigDecimal("198.75")
+        );
+
+        assertEquals(new BigDecimal("2.5"), share.getQuantity());
+        assertEquals(new BigDecimal("198.75"), share.getPurchasePrice());
+    }
+
+    @Test
+    void getStockReturnsCorrectStockObject() {
+        Stock stock = new Stock("NVDA", "NVIDIA Corporation", new BigDecimal("875.40"));
+        Share share = new Share(stock, new BigDecimal("4"), new BigDecimal("850.00"));
+
+        assertSame(stock, share.getStock());
+        assertEquals("NVDA", share.getStock().getSymbol());
+        assertEquals("NVIDIA Corporation", share.getStock().getCompany());
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/TransactionArchiveTest.java b/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/TransactionArchiveTest.java
index cf935b8..17726ad 100644
--- a/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/TransactionArchiveTest.java
+++ b/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/TransactionArchiveTest.java
@@ -1,3 +1,130 @@
-public class TransactionArchiveTest {
-    
-}
+package edu.ntnu.idi.idatt2003.g40.mappe;
+
+import org.junit.jupiter.api.Test;
+
+import java.math.BigDecimal;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class TransactionArchiveTest {
+
+    private final TransactionCalculator calculator = new TransactionCalculator() {
+        @Override
+        public BigDecimal calculateGross() {
+            return BigDecimal.ZERO;
+        }
+
+        @Override
+        public BigDecimal calculateCommission() {
+            return BigDecimal.ZERO;
+        }
+
+        @Override
+        public BigDecimal calculateTax() {
+            return BigDecimal.ZERO;
+        }
+
+        @Override
+        public BigDecimal calculateTotal() {
+            return BigDecimal.ZERO;
+        }
+    };
+
+    @Test
+    void newArchiveIsEmpty() {
+        TransactionArchive archive = new TransactionArchive();
+
+        assertTrue(archive.isEmpty());
+    }
+
+    @Test
+    void addMakesArchiveNonEmpty() {
+        TransactionArchive archive = new TransactionArchive();
+        Transaction transaction = createPurchase("AAPL", "Apple", 1);
+
+        boolean result = archive.add(transaction);
+
+        assertTrue(result);
+        assertFalse(archive.isEmpty());
+    }
+
+    @Test
+    void getTransactionsReturnsOnlyTransactionsFromGivenWeek() {
+        TransactionArchive archive = new TransactionArchive();
+
+        Transaction transaction1 = createPurchase("AAPL", "Apple", 1);
+        Transaction transaction2 = createSale("TSLA", "Tesla", 2);
+        Transaction transaction3 = createPurchase("NVDA", "Nvidia", 1);
+
+        archive.add(transaction1);
+        archive.add(transaction2);
+        archive.add(transaction3);
+
+        List<Transaction> result = archive.getTransactions(1);
+
+        assertEquals(2, result.size());
+        assertTrue(result.contains(transaction1));
+        assertTrue(result.contains(transaction3));
+    }
+
+    @Test
+    void getPurchasesReturnsOnlyPurchasesFromGivenWeek() {
+        TransactionArchive archive = new TransactionArchive();
+
+        Purchase purchase1 = createPurchase("AAPL", "Apple", 1);
+        Purchase purchase2 = createPurchase("NVDA", "Nvidia", 2);
+        Sale sale = createSale("TSLA", "Tesla", 1);
+
+        archive.add(purchase1);
+        archive.add(purchase2);
+        archive.add(sale);
+
+        List<Purchase> result = archive.getPurchases(1);
+
+        assertEquals(1, result.size());
+        assertTrue(result.contains(purchase1));
+    }
+
+    @Test
+    void getSalesReturnsOnlySalesFromGivenWeek() {
+        TransactionArchive archive = new TransactionArchive();
+
+        Sale sale1 = createSale("TSLA", "Tesla", 1);
+        Sale sale2 = createSale("NVDA", "Nvidia", 2);
+        Purchase purchase = createPurchase("AAPL", "Apple", 1);
+
+        archive.add(sale1);
+        archive.add(sale2);
+        archive.add(purchase);
+
+        List<Sale> result = archive.getSales(1);
+
+        assertEquals(1, result.size());
+        assertTrue(result.contains(sale1));
+    }
+
+    @Test
+    void countDistinctWeeksCountsUniqueWeeksOnly() {
+        TransactionArchive archive = new TransactionArchive();
+
+        archive.add(createPurchase("AAPL", "Apple", 1));
+        archive.add(createSale("TSLA", "Tesla", 1));
+        archive.add(createPurchase("NVDA", "Nvidia", 2));
+        archive.add(createSale("META", "Meta", 3));
+
+        assertEquals(3, archive.countDistinctWeeks());
+    }
+
+    private Purchase createPurchase(String symbol, String company, int week) {
+        Stock stock = new Stock(symbol, company, new BigDecimal("100"));
+        Share share = new Share(stock, BigDecimal.ONE, new BigDecimal("100"));
+        return new Purchase(share, week, calculator);
+    }
+
+    private Sale createSale(String symbol, String company, int week) {
+        Stock stock = new Stock(symbol, company, new BigDecimal("100"));
+        Share share = new Share(stock, BigDecimal.ONE, new BigDecimal("100"));
+        return new Sale(share, week, calculator);
+    }
+}
\ No newline at end of file