diff --git a/java-collections-maps/src/test/java/com/baeldung/java/map/ImmutableMapUnitTest.java b/java-collections-maps/src/test/java/com/baeldung/java/map/ImmutableMapUnitTest.java new file mode 100644 index 0000000000..b239ae07d8 --- /dev/null +++ b/java-collections-maps/src/test/java/com/baeldung/java/map/ImmutableMapUnitTest.java @@ -0,0 +1,87 @@ +package com.baeldung.java.map; + +import static org.junit.jupiter.api.Assertions.assertFalse; +import static org.junit.jupiter.api.Assertions.assertThrows; +import static org.junit.jupiter.api.Assertions.assertTrue; + +import java.util.Collections; +import java.util.HashMap; +import java.util.Map; + +import org.junit.jupiter.api.Test; + +import com.google.common.collect.ImmutableMap; + + +public class ImmutableMapUnitTest { + + @Test + public void whenCollectionsUnModifiableMapMethod_thenOriginalCollectionChangesReflectInUnmodifiableMap() { + + Map mutableMap = new HashMap<>(); + mutableMap.put("USA", "North America"); + + Map unmodifiableMap = Collections.unmodifiableMap(mutableMap); + assertThrows(UnsupportedOperationException.class, () -> unmodifiableMap.put("Canada", "North America")); + + mutableMap.remove("USA"); + assertFalse(unmodifiableMap.containsKey("USA")); + + mutableMap.put("Mexico", "North America"); + assertTrue(unmodifiableMap.containsKey("Mexico")); + } + + @Test + @SuppressWarnings("deprecation") + public void whenGuavaImmutableMapFromCopyOfMethod_thenOriginalCollectionChangesDoNotReflectInImmutableMap() { + + Map mutableMap = new HashMap<>(); + mutableMap.put("USA", "North America"); + + ImmutableMap immutableMap = ImmutableMap.copyOf(mutableMap); + assertTrue(immutableMap.containsKey("USA")); + + assertThrows(UnsupportedOperationException.class, () -> immutableMap.put("Canada", "North America")); + + mutableMap.remove("USA"); + assertTrue(immutableMap.containsKey("USA")); + + mutableMap.put("Mexico", "North America"); + assertFalse(immutableMap.containsKey("Mexico")); + } + + @Test + @SuppressWarnings("deprecation") + public void whenGuavaImmutableMapFromBuilderMethod_thenOriginalCollectionChangesDoNotReflectInImmutableMap() { + + Map mutableMap = new HashMap<>(); + mutableMap.put("USA", "North America"); + + ImmutableMap immutableMap = ImmutableMap.builder() + .putAll(mutableMap) + .put("Costa Rica", "North America") + .build(); + assertTrue(immutableMap.containsKey("USA")); + assertTrue(immutableMap.containsKey("Costa Rica")); + + assertThrows(UnsupportedOperationException.class, () -> immutableMap.put("Canada", "North America")); + + mutableMap.remove("USA"); + assertTrue(immutableMap.containsKey("USA")); + + mutableMap.put("Mexico", "North America"); + assertFalse(immutableMap.containsKey("Mexico")); + } + + @Test + @SuppressWarnings("deprecation") + public void whenGuavaImmutableMapFromOfMethod_thenOriginalCollectionChangesDoNotReflectInImmutableMap() { + + ImmutableMap immutableMap = ImmutableMap.of("USA", "North America", "Costa Rica", "North America"); + assertTrue(immutableMap.containsKey("USA")); + assertTrue(immutableMap.containsKey("Costa Rica")); + + assertThrows(UnsupportedOperationException.class, () -> immutableMap.put("Canada", "North America")); + } + +}