Added tests

src/test/java/com/apptasticsoftware/integrationtest/SortTest.java

@@ -38,7 +38,9 @@ void testTimestampSortTest() {
                 "https://www.politico.com/rss/politicopicks.xml",
                 "https://www.e1.ru/talk/forum/rss.php?f=86",
                 "https://failed-to-read-from-this-url.com",
-                "https://www.nrdc.org/rss.xml");
+                "https://www.nrdc.org/rss.xml",
+                "https://www.theverge.com/rss/reviews/index.xml",
+                "https://feeds.macrumors.com/MacRumors-All");
 
 
         List<String> extendedUrlList = new ArrayList<>(urlList);

src/test/java/com/apptasticsoftware/rssreader/util/ItemComparatorTest.java

@@ -0,0 +1,94 @@
+package com.apptasticsoftware.rssreader.util;
+
+import com.apptasticsoftware.rssreader.DateTime;
+import com.apptasticsoftware.rssreader.RssReader;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+import java.time.ZonedDateTime;
+import java.util.List;
+import java.util.Objects;
+import java.util.stream.Collectors;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class ItemComparatorTest {
+
+    @Test
+    void testSortNewestItem() throws IOException {
+        var items = new RssReader().read("https://www.theverge.com/rss/reviews/index.xml")
+                .sorted(ItemComparator.newestItemFirst())
+                .map(i -> i.getPubDateZonedDateTime().orElse(null))
+                .filter(Objects::nonNull)
+                .map(ZonedDateTime::toEpochSecond)
+                .collect(Collectors.toList());
+
+        assertTrue(isDescendingSortOrder(items));
+    }
+
+    @Test
+    void testSortNewestItemWithDateTimeParser() throws IOException {
+        var items = new RssReader().read("https://www.theverge.com/rss/reviews/index.xml")
+                .sorted(ItemComparator.newestItemFirst(new DateTime()))
+                .map(i -> i.getPubDateZonedDateTime().orElse(null))
+                .filter(Objects::nonNull)
+                .map(ZonedDateTime::toEpochSecond)
+                .collect(Collectors.toList());
+
+        assertTrue(isDescendingSortOrder(items));
+    }
+
+    @Test
+    void testSortOldestItemFirst() throws IOException {
+        var items = new RssReader().read("https://www.theverge.com/rss/reviews/index.xml")
+                                   .sorted(ItemComparator.oldestItemFirst())
+                                   .map(i -> i.getPubDateZonedDateTime().orElse(null))
+                                   .filter(Objects::nonNull)
+                                   .collect(Collectors.toList());
+
+        assertTrue(isAscendingSortOrder(items));
+    }
+
+    @Test
+    void testSortOldestItemFirstWithDateTimeParser() throws IOException {
+        var items = new RssReader().read("https://www.theverge.com/rss/reviews/index.xml")
+                .sorted(ItemComparator.oldestItemFirst(new DateTime()))
+                .map(i -> i.getPubDateZonedDateTime().orElse(null))
+                .filter(Objects::nonNull)
+                .collect(Collectors.toList());
+
+        assertTrue(isAscendingSortOrder(items));
+    }
+
+    @Test
+    void testSortChannelTitle() {
+        var urlList = List.of("https://www.theverge.com/rss/reviews/index.xml", "https://feeds.macrumors.com/MacRumors-All");
+        var items = new RssReader().read(urlList)
+                .sorted(ItemComparator.channelTitle())
+                .map(i -> i.getChannel().getTitle())
+                .filter(Objects::nonNull)
+                .collect(Collectors.toList());
+
+        assertTrue(isAscendingSortOrder(items));
+    }
+
+
+    private static <T extends Comparable<? super T>> boolean isAscendingSortOrder(List<T> array){
+        for (int i = 0; i < array.size()-1; i++) {
+            if (array.get(i).compareTo(array.get(i+1)) > 0){
+                return false;
+            }
+        }
+        return true;
+    }
+
+    private static <T extends Comparable<? super T>> boolean isDescendingSortOrder(List<T> array){
+        for (int i = 0; i < array.size()-1; i++) {
+            if (array.get(i).compareTo(array.get(i+1)) < 0){
+                return false;
+            }
+        }
+        return true;
+    }
+
+}