add basic usage as test

spring-boot-modules/spring-boot-libraries/src/test/java/com/baledung/ratelimiting/bucket4j/Bucket4jUsageTest.java

@@ -0,0 +1,82 @@
+package com.baledung.ratelimiting.bucket4j;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import java.time.Duration;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+
+import org.junit.jupiter.api.Test;
+
+import io.github.bucket4j.Bandwidth;
+import io.github.bucket4j.Bucket;
+import io.github.bucket4j.Bucket4j;
+import io.github.bucket4j.Refill;
+
+public class Bucket4jUsageTest {
+
+    @Test
+    public void givenBucketLimit_whenExceedLimit_thenConsumeReturnsFalse() {
+        Refill refill = Refill.intervally(10, Duration.ofMinutes(1));
+        Bandwidth limit = Bandwidth.classic(10, refill);
+        Bucket bucket = Bucket4j.builder()
+            .addLimit(limit)
+            .build();
+
+        for (int i = 1; i <= 10; i++) {
+            assertTrue(bucket.tryConsume(1));
+        }
+        assertFalse(bucket.tryConsume(1));
+    }
+
+    @Test
+    public void givenMultipletLimits_whenExceedSmallerLimit_thenConsumeReturnsFalse() {
+        Bucket bucket = Bucket4j.builder()
+            .addLimit(Bandwidth.classic(10, Refill.intervally(10, Duration.ofMinutes(1))))
+            .addLimit(Bandwidth.classic(5, Refill.intervally(5, Duration.ofSeconds(20))))
+            .build();
+
+        for (int i = 1; i <= 5; i++) {
+            assertTrue(bucket.tryConsume(1));
+        }
+        assertFalse(bucket.tryConsume(1));
+    }
+
+    @Test
+    public void givenBucketLimit_whenThrottleRequests_thenConsumeReturnsTrue() throws InterruptedException {
+        Refill refill = Refill.intervally(1, Duration.ofSeconds(2));
+        Bandwidth limit = Bandwidth.classic(1, refill);
+        Bucket bucket = Bucket4j.builder()
+            .addLimit(limit)
+            .build();
+
+        assertTrue(bucket.tryConsume(1));
+
+        ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
+        CountDownLatch latch = new CountDownLatch(1);
+
+        executor.schedule(new AssertTryConsume(bucket, latch), 2, TimeUnit.SECONDS);
+
+        latch.await();
+    }
+
+    static class AssertTryConsume implements Runnable {
+
+        private Bucket bucket;
+        private CountDownLatch latch;
+
+        AssertTryConsume(Bucket bucket, CountDownLatch latch) {
+            this.bucket = bucket;
+            this.latch = latch;
+        }
+
+        @Override
+        public void run() {
+            assertTrue(bucket.tryConsume(1));
+            latch.countDown();
+        }
+    }
+}