Unit Test PurchaseCalculator class

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());
+    }
+}