iluwatar#1263 - creating ProductViewHelper and its test

Author: e5LA

view-helper/src/main/java/com/iluwatar/viewhelper/ProductViewHelper.java

@@ -0,0 +1,23 @@
+package com.iluwatar.viewhelper;
+
+import static java.time.format.DateTimeFormatter.ISO_DATE;
+import static java.util.Locale.US;
+
+import java.text.NumberFormat;
+
+/**
+ * Formats a {@link Product} into a {@link ProductViewModel}.
+ */
+public class ProductViewHelper implements ViewHelper<Product, ProductViewModel> {
+
+  private static final String DISCOUNT_TAG = " ON SALE";
+
+  @Override
+  public ProductViewModel prepare(Product product) {
+    var displayName = product.name() + (product.discounted() ? DISCOUNT_TAG : "");
+    var priceWithCurrency = NumberFormat.getCurrencyInstance(US).format(product.price());
+    var formattedDate = product.releaseDate().format(ISO_DATE);
+
+    return new ProductViewModel(displayName, priceWithCurrency, formattedDate);
+  }
+}

view-helper/src/test/java/com/iluwatar/viewhelper/ProductViewHelperTest.java

@@ -0,0 +1,36 @@
+package com.iluwatar.viewhelper;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+class ProductViewHelperTest {
+
+  private ProductViewHelper helper;
+
+  @BeforeEach
+  void setUp() {
+    helper = new ProductViewHelper();
+  }
+
+  @Test
+  void shouldFormatProductWithoutDiscount() {
+    var product = new Product("X", new BigDecimal("10.00"), LocalDate.of(2025, 1, 1), false);
+    ProductViewModel viewModel = helper.prepare(product);
+
+    assertEquals("X", viewModel.name());
+    assertEquals("$10.00", viewModel.price());
+    assertEquals("2025-01-01", viewModel.releasedDate());
+  }
+
+  @Test
+  void shouldFormatProductWithDiscount() {
+    var product = new Product("X", new BigDecimal("10.00"), LocalDate.of(2025, 1, 1), true);
+    ProductViewModel viewModel = helper.prepare(product);
+
+    assertEquals("X ON SALE", viewModel.name());       // locale follows JVM default
+  }
+}