add unit tests for Exchange class

src/test/java/edu/ntnu/idi/idatt2003/gruppe42/ExchangeTest.java

@@ -0,0 +1,48 @@
+package edu.ntnu.idi.idatt2003.gruppe42;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import edu.ntnu.idi.idatt2003.gruppe42.Model.Exchange;
+import edu.ntnu.idi.idatt2003.gruppe42.Model.Stock;
+import java.math.BigDecimal;
+import java.util.List;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class ExchangeTest {
+
+  private Exchange exchange;
+
+  @BeforeEach
+  public void setUp() {
+    Stock stock = new Stock("AAPL", "Apple Inc.", new BigDecimal("100"));
+    exchange = new Exchange("NYSE", List.of(stock));
+  }
+
+  @Test
+  void findStocksTest() {
+    List<Stock> result = exchange.findStocks("Apple Inc.");
+
+    assertEquals(1, result.size());
+    assertEquals("Apple Inc.", result.get(0).getCompany());
+  }
+
+  @Test
+  void findStocksNullTest() {
+    List<Stock> result = exchange.findStocks("Google");
+
+    assertTrue(result.isEmpty());
+  }
+
+  @Test
+  void advanceTest() {
+    assertEquals(0, exchange.getWeek());
+    exchange.advance();
+
+    assertEquals(1, exchange.getWeek());
+    exchange.advance();
+
+    assertEquals(2, exchange.getWeek());
+  }
+}