test: adding playerTest

src/test/java/millions/PlayerTest.java

@@ -2,4 +2,37 @@
 
 import static org.junit.jupiter.api.Assertions.*;
 
-class PlayerTest {}
+import java.math.BigDecimal;
+import org.junit.jupiter.api.Test;
+
+class PlayerTest {
+
+  @Test
+  public void happyPath() {
+    Player player = new Player("name", BigDecimal.valueOf(1000));
+    assertEquals(BigDecimal.valueOf(1000), player.getMoney());
+
+    player.addMoney(BigDecimal.valueOf(500));
+    assertEquals(BigDecimal.valueOf(1500), player.getMoney());
+
+    player.withdrawMoney(BigDecimal.valueOf(200));
+    assertEquals(BigDecimal.valueOf(1300), player.getMoney());
+  }
+
+  @Test
+  public void testGetters() {
+    Player player = new Player("name", BigDecimal.valueOf(1000));
+    assertEquals("name", player.getName());
+    assertEquals(BigDecimal.valueOf(1000), player.getMoney());
+    assertTrue(player.getPortfolio().getShares().isEmpty());
+    assertTrue(player.getTransactionArchive().isEmpty());
+  }
+
+  @Test
+  public void testNullsAndInvalid() {
+    assertThrows(IllegalArgumentException.class, () -> new Player(null, BigDecimal.valueOf(1000)));
+    assertThrows(IllegalArgumentException.class, () -> new Player("", BigDecimal.valueOf(1000)));
+    assertThrows(IllegalArgumentException.class, () -> new Player("name", null));
+    assertThrows(IllegalArgumentException.class, () -> new Player("name", BigDecimal.valueOf(-1)));
+  }
+}