[map-KV-to-list] Get Values and Keys as ArralyLists From a HashMap (#14615)

core-java-modules/core-java-collections-maps-3/src/test/java/com/baeldung/map/hashmap/kvtolist/MapKeysValuesToListUnitTest.java

@@ -0,0 +1,72 @@
+package com.baeldung.map.hashmap.kvtolist;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.junit.jupiter.api.Test;
+
+public class MapKeysValuesToListUnitTest {
+    private static final HashMap<String, String> DEV_MAP;
+
+    static {
+        DEV_MAP = new HashMap<>();
+        DEV_MAP.put("Kent", "Linux");
+        DEV_MAP.put("Eric", "MacOS");
+        DEV_MAP.put("Kevin", "Windows");
+        DEV_MAP.put("Michal", "MacOS");
+        DEV_MAP.put("Saajan", "Linux");
+    }
+
+    @Test
+    void whenUsingKeySet_thenGetExpectedResult() {
+        List<String> keyList = new ArrayList<>(DEV_MAP.keySet());
+        // this assertion may fail, since hashMap doesn't preserve the insertion order
+        // assertEquals(Lists.newArrayList("Kent", "Eric", "Kevin", "Michal", "Saajan"), keyList);
+
+        assertThat(keyList).containsExactlyInAnyOrder("Kent", "Eric", "Kevin", "Michal", "Saajan");
+
+    }
+
+    @Test
+    void whenUsingValues_thenGetExpectedResult() {
+        List<String> valueList = new ArrayList<>(DEV_MAP.values());
+        assertThat(valueList).containsExactlyInAnyOrder("Linux", "MacOS", "Windows", "MacOS", "Linux");
+    }
+
+    @Test
+    void whenLoopingEntries_thenGetExpectedResult() {
+        List<String> keyList = new ArrayList<>();
+        List<String> valueList = new ArrayList<>();
+        for (Map.Entry<String, String> entry : DEV_MAP.entrySet()) {
+            keyList.add(entry.getKey());
+            valueList.add(entry.getValue());
+        }
+
+        assertKeyAndValueList(keyList, valueList);
+
+    }
+
+    @Test
+    void whenUsingForEach_thenGetExpectedResult() {
+        List<String> keyList = new ArrayList<>();
+        List<String> valueList = new ArrayList<>();
+        DEV_MAP.forEach((k, v) -> {
+            keyList.add(k);
+            valueList.add(v);
+        });
+
+        assertKeyAndValueList(keyList, valueList);
+    }
+
+    private void assertKeyAndValueList(List<String> keyList, List<String> valueList) {
+        assertThat(keyList).containsExactlyInAnyOrder("Kent", "Eric", "Kevin", "Michal", "Saajan");
+        assertThat(valueList).containsExactlyInAnyOrder("Linux", "MacOS", "Windows", "MacOS", "Linux");
+        for (int i = 0; i < keyList.size(); i++) {
+            assertThat(DEV_MAP).containsEntry(keyList.get(i), valueList.get(i));
+        }
+    }
+}