diff --git a/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/model/ShareTest.java b/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/model/ShareTest.java
index bb78ea1..f73a2e4 100644
--- a/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/model/ShareTest.java
+++ b/src/test/java/edu/ntnu/idi/idatt2003/g40/mappe/model/ShareTest.java
@@ -1,52 +1,114 @@
 package edu.ntnu.idi.idatt2003.g40.mappe.model;
 
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import java.math.BigDecimal;
 
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 final class ShareTest {
 
-  @Test
-  void constructorStoresAllValuesCorrectly() {
-    Stock stock = new Stock("AAPL", "Apple Inc.", new BigDecimal("150.00"));
+  /**
+   * Share to use for testing.
+   */
+  private Share testShare;
+
+  /**
+   * Stock to use for testing.
+   * */
+  private Stock testStock;
+
+  @BeforeEach
+  void setUp() {
+    testStock = new Stock(
+            "AAPL",
+            "Apple Inc.",
+            new BigDecimal("150.00")
+    );
     BigDecimal quantity = new BigDecimal("10");
     BigDecimal purchasePrice = new BigDecimal("145.50");
+    testShare = new Share(testStock, quantity, purchasePrice);
+  }
+
+  @Test
+  void constructorStoresAllValuesCorrectly() {
+    assertSame(testStock, testShare.getStock());
+
+    assertEquals(0,
+            new BigDecimal("10")
+            .compareTo(testShare.getQuantity())
+    );
+
+    assertEquals(0,
+            new BigDecimal("145.50")
+            .compareTo(testShare.getPurchasePrice())
+    );
+  }
+
+  @Test
+  void constructorThrowsExceptionOnIllegalArguments() {
+    assertDoesNotThrow(
+            () -> new Share(testStock, new BigDecimal("1"),
+                    new BigDecimal("100"))
+    );
+
+    assertThrows(IllegalArgumentException.class,
+            () -> new Share(null, new BigDecimal("1"), new BigDecimal("100"))
+    );
+
+    assertThrows(IllegalArgumentException.class,
+            () -> new Share(testStock, null, new BigDecimal("100"))
+    );
+
+    assertThrows(IllegalArgumentException.class,
+            () -> new Share(testStock, new BigDecimal("1"), null)
+    );
 
-    Share share = new Share(stock, quantity, purchasePrice);
+    assertThrows(IllegalArgumentException.class,
+            () -> new Share(testStock, new BigDecimal("0"),
+                    new BigDecimal("100"))
+    );
 
-    assertSame(stock, share.getStock());
-    assertEquals(quantity, share.getQuantity());
-    assertEquals(purchasePrice, share.getPurchasePrice());
+    assertThrows(IllegalArgumentException.class,
+            () -> new Share(testStock, new BigDecimal("1"), new BigDecimal("0"))
+    );
   }
 
   @Test
   void shareSupportsDecimalValues() {
-    Stock stock = new Stock("TSLA", "Tesla Inc.", new BigDecimal("200.00"));
 
-    Share share = new Share(
-            stock,
+    Share testShare2 = new Share(
+            testStock,
             new BigDecimal("2.5"),
             new BigDecimal("198.75")
     );
 
-    assertEquals(new BigDecimal("2.5"), share.getQuantity());
-    assertEquals(new BigDecimal("198.75"), share.getPurchasePrice());
+    assertEquals(0,
+            new BigDecimal("2.5")
+            .compareTo(testShare2.getQuantity())
+    );
+
+    assertEquals(0,
+            new BigDecimal("198.75")
+            .compareTo(testShare2.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());
+    assertSame(testStock, testShare.getStock());
+    assertEquals(
+            "AAPL",
+            testShare.getStock().getSymbol()
+    );
+
+    assertEquals(
+            "Apple Inc.",
+            testShare.getStock().getCompany()
+    );
   }
 }