<dependency>
    <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>29.0-jre</version>
</dependency>

@Test
    public void whenCacheMiss_thenValueIsComputed() {
        CacheLoader<String, String> loader;

        loader = new CacheLoader<String, String>() {
            @Override
            public String load(String key) {
                return key.toUpperCase();
            }
        };

        LoadingCache<String, String> cache;
        cache = CacheBuilder.newBuilder().build(loader);

        assertEquals(0, cache.size());
        assertEquals("HELLO", cache.getUnchecked("hello"));
        assertEquals(1, cache.size());
    }




    @Test
    public void whenCacheReachMaxSize_thenEviction() {
        CacheLoader<String, String> loader;
        loader = new CacheLoader<String, String>() {
            @Override
            public String load(String key) {
                return key.toUpperCase();
            }
        };
        LoadingCache<String, String> cache;
        cache = CacheBuilder.newBuilder().maximumSize(3).build(loader);

        cache.getUnchecked("first");
        cache.getUnchecked("second");
        cache.getUnchecked("third");
        cache.getUnchecked("forth");
        assertEquals(3, cache.size());
        assertNull(cache.getIfPresent("first"));
        assertEquals("FORTH", cache.getIfPresent("forth"));
    }


@Test
    public void whenEntryIdle_thenEviction() throws InterruptedException {
        CacheLoader<String, String> loader;
        loader = new CacheLoader<String, String>() {
            @Override
            public String load(String key) {
                return key.toUpperCase();
            }
        };

        LoadingCache<String, String> cache;
        cache = CacheBuilder.newBuilder()
                .expireAfterAccess(2, TimeUnit.MILLISECONDS)
                .build(loader);

        cache.getUnchecked("hello");
        assertEquals(1, cache.size());

        cache.getUnchecked("hello");
        Thread.sleep(300);

        cache.getUnchecked("test");
        assertEquals(1, cache.size());
        assertNull(cache.getIfPresent("hello"));
    }