Unit test SaleCalculator class

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());
+    }
+}