fix: Fix test stability issues

iluwatar · iluwatar · commit 177dc527043d · 2026-06-07T12:10:39.000+03:00
diff --git a/health-check/src/main/java/com/iluwatar/health/check/App.java b/health-check/src/main/java/com/iluwatar/health/check/App.java
@@ -43,6 +43,11 @@
 public class App {
   /** Program entry point. */
   public static void main(String[] args) {
-    SpringApplication.run(App.class, args);
+    var context = SpringApplication.run(App.class, args);
+    if (args.length > 0 && "test".equals(args[0])) {
+      // Close the context immediately during tests to prevent Tomcat/background threads from
+      // hanging the JVM
+      context.close();
+    }
   }
 }
diff --git a/health-check/src/test/java/AppTest.java b/health-check/src/test/java/AppTest.java
@@ -33,6 +33,6 @@ class AppTest {
   /** Entry point */
   @Test
   void shouldExecuteApplicationWithoutException() {
-    assertDoesNotThrow(() -> App.main(new String[] {}));
+    assertDoesNotThrow(() -> App.main(new String[] {"test"}));
   }
 }
diff --git a/microservices-distributed-tracing/order-microservice/src/main/java/com/iluwatar/order/microservice/Main.java b/microservices-distributed-tracing/order-microservice/src/main/java/com/iluwatar/order/microservice/Main.java
@@ -73,6 +73,11 @@ public class Main {
    * @param args command line args
    */
   public static void main(String[] args) {
-    SpringApplication.run(Main.class, args);
+    var context = SpringApplication.run(Main.class, args);
+    if (args.length > 0 && "test".equals(args[0])) {
+      // Close the context immediately during tests to prevent Tomcat/background threads from
+      // hanging the JVM
+      context.close();
+    }
   }
 }
diff --git a/microservices-distributed-tracing/order-microservice/src/test/java/com/iluwatar/order/microservice/MainTest.java b/microservices-distributed-tracing/order-microservice/src/test/java/com/iluwatar/order/microservice/MainTest.java
@@ -32,6 +32,6 @@
 class MainTest {
   @Test
   void shouldExecuteApplicationWithoutException() {
-    assertDoesNotThrow(() -> Main.main(new String[] {}));
+    assertDoesNotThrow(() -> Main.main(new String[] {"test"}));
   }
 }
diff --git a/microservices-distributed-tracing/payment-microservice/src/main/java/com/iluwatar/payment/microservice/Main.java b/microservices-distributed-tracing/payment-microservice/src/main/java/com/iluwatar/payment/microservice/Main.java
@@ -72,6 +72,11 @@ public class Main {
    * @param args command line args
    */
   public static void main(String[] args) {
-    SpringApplication.run(Main.class, args);
+    var context = SpringApplication.run(Main.class, args);
+    if (args.length > 0 && "test".equals(args[0])) {
+      // Close the context immediately during tests to prevent Tomcat/background threads from
+      // hanging the JVM
+      context.close();
+    }
   }
 }
diff --git a/microservices-distributed-tracing/payment-microservice/src/test/java/com/iluwatar/payment/microservice/MainTest.java b/microservices-distributed-tracing/payment-microservice/src/test/java/com/iluwatar/payment/microservice/MainTest.java
@@ -32,6 +32,6 @@
 class MainTest {
   @Test
   void shouldExecuteApplicationWithoutException() {
-    assertDoesNotThrow(() -> Main.main(new String[] {}));
+    assertDoesNotThrow(() -> Main.main(new String[] {"test"}));
   }
 }
diff --git a/microservices-distributed-tracing/product-microservice/src/main/java/com/iluwatar/product/microservice/microservice/Main.java b/microservices-distributed-tracing/product-microservice/src/main/java/com/iluwatar/product/microservice/microservice/Main.java
@@ -72,6 +72,11 @@ public class Main {
    * @param args command line args
    */
   public static void main(String[] args) {
-    SpringApplication.run(Main.class, args);
+    var context = SpringApplication.run(Main.class, args);
+    if (args.length > 0 && "test".equals(args[0])) {
+      // Close the context immediately during tests to prevent Tomcat/background threads from
+      // hanging the JVM
+      context.close();
+    }
   }
 }
diff --git a/microservices-distributed-tracing/product-microservice/src/test/java/com/iluwatar/product/microservice/MainTest.java b/microservices-distributed-tracing/product-microservice/src/test/java/com/iluwatar/product/microservice/MainTest.java
@@ -33,6 +33,6 @@
 class MainTest {
   @Test
   void shouldExecuteApplicationWithoutException() {
-    assertDoesNotThrow(() -> Main.main(new String[] {}));
+    assertDoesNotThrow(() -> Main.main(new String[] {"test"}));
   }
 }
diff --git a/microservices-idempotent-consumer/src/main/java/com/iluwatar/idempotentconsumer/App.java b/microservices-idempotent-consumer/src/main/java/com/iluwatar/idempotentconsumer/App.java
@@ -45,7 +45,12 @@
 @Slf4j
 public class App {
   public static void main(String[] args) {
-    SpringApplication.run(App.class, args);
+    var context = SpringApplication.run(App.class, args);
+    if (args.length > 0 && "test".equals(args[0])) {
+      // Close the context immediately during tests to prevent Tomcat/background threads from
+      // hanging the JVM
+      context.close();
+    }
   }
 
   /**
diff --git a/microservices-idempotent-consumer/src/test/java/com/iluwatar/idempotentconsumer/AppTest.java b/microservices-idempotent-consumer/src/test/java/com/iluwatar/idempotentconsumer/AppTest.java
@@ -40,7 +40,7 @@ class AppTest {
 
   @Test
   void testMain() {
-    assertDoesNotThrow(() -> App.main(new String[] {}));
+    assertDoesNotThrow(() -> App.main(new String[] {"test"}));
   }
 
   @Test
diff --git a/page-controller/src/main/java/com/iluwatar/page/controller/App.java b/page-controller/src/main/java/com/iluwatar/page/controller/App.java
@@ -44,6 +44,11 @@ public class App {
    * @param args command line args
    */
   public static void main(final String[] args) {
-    SpringApplication.run(App.class, args);
+    var context = SpringApplication.run(App.class, args);
+    if (args.length > 0 && "test".equals(args[0])) {
+      // Close the context immediately during tests to prevent Tomcat/background threads from
+      // hanging the JVM
+      context.close();
+    }
   }
 }
diff --git a/page-controller/src/test/java/com/iluwatar/page/controller/AppTest.java b/page-controller/src/test/java/com/iluwatar/page/controller/AppTest.java
@@ -32,6 +32,6 @@
 public class AppTest {
   @Test
   void shouldExecuteApplicationWithoutException() {
-    assertDoesNotThrow(() -> App.main(new String[] {}));
+    assertDoesNotThrow(() -> App.main(new String[] {"test"}));
   }
 }
diff --git a/polling-publisher/polling-service/src/main/java/com/iluwatar/polling/App.java b/polling-publisher/polling-service/src/main/java/com/iluwatar/polling/App.java
@@ -40,6 +40,11 @@ public class App {
    * @param args command line args.
    */
   public static void main(String[] args) {
-    SpringApplication.run(App.class, args);
+    var context = SpringApplication.run(App.class, args);
+    if (args.length > 0 && "test".equals(args[0])) {
+      // Close the context immediately during tests to prevent Tomcat/background threads from
+      // hanging the JVM
+      context.close();
+    }
   }
 }
diff --git a/polling-publisher/polling-service/src/main/java/com/iluwatar/polling/DataSourceService.java b/polling-publisher/polling-service/src/main/java/com/iluwatar/polling/DataSourceService.java
@@ -44,9 +44,22 @@ public class DataSourceService {
   private final ScheduledExecutorService scheduler = Executors.newSingleThreadScheduledExecutor();
 
   /** Constructor & Scheduler to push random data. */
+  @org.springframework.beans.factory.annotation.Autowired
   public DataSourceService(DataRepository repository) {
+    this(repository, true);
+  }
+
+  /**
+   * Constructor with option to start the scheduler.
+   *
+   * @param repository the data repository
+   * @param startScheduler true to start the data generation scheduler
+   */
+  public DataSourceService(DataRepository repository, boolean startScheduler) {
     this.repository = repository;
-    scheduleDataGeneration();
+    if (startScheduler) {
+      scheduleDataGeneration();
+    }
   }
 
   private void scheduleDataGeneration() {
@@ -78,4 +91,9 @@ public void removeData(int id) {
   public Map<Integer, String> getAllData() {
     return repository.findAll();
   }
+
+  @javax.annotation.PreDestroy
+  public void shutdown() {
+    scheduler.shutdown();
+  }
 }
diff --git a/polling-publisher/polling-service/src/test/java/com/iluwatar/polling/AppTest.java b/polling-publisher/polling-service/src/test/java/com/iluwatar/polling/AppTest.java
@@ -28,12 +28,16 @@
 
 import org.junit.jupiter.api.Test;
 import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.kafka.test.context.EmbeddedKafka;
 
 @SpringBootTest
+@EmbeddedKafka(
+    partitions = 1,
+    topics = {"updates", "API"})
 public class AppTest {
 
   @Test
   void polling() {
-    assertDoesNotThrow(() -> App.main(new String[] {}));
+    assertDoesNotThrow(() -> App.main(new String[] {"test"}));
   }
 }
diff --git a/polling-publisher/polling-service/src/test/java/com/iluwatar/polling/DataSourceServiceTest.java b/polling-publisher/polling-service/src/test/java/com/iluwatar/polling/DataSourceServiceTest.java
@@ -38,7 +38,7 @@ public class DataSourceServiceTest {
   @BeforeEach
   void setUp() {
     repository = new DataRepository();
-    service = new DataSourceService(repository);
+    service = new DataSourceService(repository, false);
   }
 
   @Test
@@ -77,8 +77,8 @@ void testGetAllData() {
 
     Map<Integer, String> result1 = service.getAllData();
 
-    assertEquals(size + 2, result.size(), "Should return all stored data.");
-    assertEquals("First", result.get(1), "Value for key 1 should be 'First'.");
-    assertEquals("Second", result.get(2), "Value for key 2 should be 'Second'.");
+    assertEquals(size + 2, result1.size(), "Should return all stored data.");
+    assertEquals("First", result1.get(1), "Value for key 1 should be 'First'.");
+    assertEquals("Second", result1.get(2), "Value for key 2 should be 'Second'.");
   }
 }
diff --git a/polling-publisher/subscriber-service/src/main/java/com/iluwatar/subscriber/App.java b/polling-publisher/subscriber-service/src/main/java/com/iluwatar/subscriber/App.java
@@ -32,6 +32,11 @@
 @SpringBootApplication
 public class App {
   public static void main(String[] args) {
-    SpringApplication.run(App.class, args);
+    var context = SpringApplication.run(App.class, args);
+    if (args.length > 0 && "test".equals(args[0])) {
+      // Close the context immediately during tests to prevent Tomcat/background threads from
+      // hanging the JVM
+      context.close();
+    }
   }
 }
diff --git a/polling-publisher/subscriber-service/src/test/java/com/iluwatar/subscriber/AppTest.java b/polling-publisher/subscriber-service/src/test/java/com/iluwatar/subscriber/AppTest.java
@@ -29,12 +29,16 @@
 
 import org.junit.jupiter.api.Test;
 import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.kafka.test.context.EmbeddedKafka;
 
 @SpringBootTest
+@EmbeddedKafka(
+    partitions = 1,
+    topics = {"updates", "API"})
 public class AppTest {
 
   @Test
   void subscriber() {
-    assertDoesNotThrow(() -> App.main(new String[] {}));
+    assertDoesNotThrow(() -> App.main(new String[] {"test"}));
   }
 }
diff --git a/rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/AdaptiveRateLimiter.java b/rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/AdaptiveRateLimiter.java
@@ -10,23 +10,39 @@ public class AdaptiveRateLimiter implements RateLimiter {
   private final AtomicInteger currentLimit;
   private final ConcurrentHashMap<String, RateLimiter> limiters = new ConcurrentHashMap<>();
   private final ScheduledExecutorService healthChecker = Executors.newScheduledThreadPool(1);
+  private final long checkInterval;
+  private final TimeUnit timeUnit;
 
   public AdaptiveRateLimiter(int initialLimit, int maxLimit) {
+    this(initialLimit, maxLimit, 10, TimeUnit.SECONDS);
+  }
+
+  /**
+   * Constructor with option to set custom interval.
+   *
+   * @param initialLimit initial rate limit
+   * @param maxLimit maximum rate limit
+   * @param interval check interval
+   * @param timeUnit check interval time unit
+   */
+  public AdaptiveRateLimiter(int initialLimit, int maxLimit, long interval, TimeUnit timeUnit) {
     this.initialLimit = initialLimit;
     this.maxLimit = maxLimit;
     this.currentLimit = new AtomicInteger(initialLimit);
-    // Periodically increase limit to recover if system appears healthy
-    healthChecker.scheduleAtFixedRate(this::adjustLimits, 10, 10, TimeUnit.SECONDS);
+    this.checkInterval = interval;
+    this.timeUnit = timeUnit;
+    healthChecker.scheduleAtFixedRate(this::adjustLimits, interval, interval, timeUnit);
   }
 
   @Override
   public void check(String serviceName, String operationName) throws RateLimitException {
     String key = serviceName + ":" + operationName;
     int current = currentLimit.get();
 
-    // Reuse or create TokenBucket for this key using currentLimit
+    // Reuse or create TokenBucket for this key using currentLimit and checkInterval
     RateLimiter limiter =
-        limiters.computeIfAbsent(key, k -> new TokenBucketRateLimiter(current, current));
+        limiters.computeIfAbsent(
+            key, k -> new TokenBucketRateLimiter(current, current, checkInterval, timeUnit));
 
     try {
       limiter.check(serviceName, operationName);
@@ -47,4 +63,17 @@ private void adjustLimits() {
     int updated = currentLimit.updateAndGet(curr -> Math.min(maxLimit, curr + (initialLimit / 2)));
     System.out.printf("[Adaptive] Health check passed - Increasing limit to %d%n", updated);
   }
+
+  /** Gracefully shut down the health checker executor and child limiters. */
+  public void shutdown() {
+    healthChecker.shutdown();
+    limiters
+        .values()
+        .forEach(
+            limiter -> {
+              if (limiter instanceof TokenBucketRateLimiter) {
+                ((TokenBucketRateLimiter) limiter).shutdown();
+              }
+            });
+  }
 }
diff --git a/rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/TokenBucketRateLimiter.java b/rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/TokenBucketRateLimiter.java
@@ -4,8 +4,10 @@
 import java.util.concurrent.atomic.AtomicInteger;
 
 /**
- * Token Bucket rate limiter implementation. Allows requests to proceed as long as there are tokens
- * available in the bucket. Tokens are added at a fixed interval up to a defined capacity.
+ * Token Bucket rate limiter implementation. Allows requests to proceed as long
+ * as there are tokens
+ * available in the bucket. Tokens are added at a fixed interval up to a defined
+ * capacity.
  */
 public class TokenBucketRateLimiter implements RateLimiter {
   private final int capacity;
@@ -14,10 +16,22 @@ public class TokenBucketRateLimiter implements RateLimiter {
   private final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);
 
   public TokenBucketRateLimiter(int capacity, int refillRate) {
+    this(capacity, refillRate, 1, TimeUnit.SECONDS);
+  }
+
+  /**
+   * Constructor with custom refill interval.
+   *
+   * @param capacity       token bucket capacity
+   * @param refillRate     token refill rate
+   * @param refillInterval refill interval value
+   * @param timeUnit       refill interval time unit
+   */
+  public TokenBucketRateLimiter(
+      int capacity, int refillRate, long refillInterval, TimeUnit timeUnit) {
     this.capacity = capacity;
     this.refillRate = refillRate;
-    // Refill tokens in all buckets every second
-    scheduler.scheduleAtFixedRate(this::refillBuckets, 1, 1, TimeUnit.SECONDS);
+    scheduler.scheduleAtFixedRate(this::refillBuckets, refillInterval, refillInterval, timeUnit);
   }
 
   @Override
@@ -39,7 +53,10 @@ private void refillBuckets() {
     buckets.forEach((k, b) -> b.refill(refillRate));
   }
 
-  /** Inner class that represents the bucket holding tokens for each service-operation. */
+  /**
+   * Inner class that represents the bucket holding tokens for each
+   * service-operation.
+   */
   private static class TokenBucket {
     private final int capacity;
     private final AtomicInteger tokens;
@@ -52,13 +69,19 @@ private static class TokenBucket {
     boolean tryConsume() {
       while (true) {
         int current = tokens.get();
-        if (current <= 0) return false;
-        if (tokens.compareAndSet(current, current - 1)) return true;
+        if (current <= 0)
+          return false;
+        if (tokens.compareAndSet(current, current - 1))
+          return true;
       }
     }
 
     void refill(int amount) {
       tokens.getAndUpdate(current -> Math.min(current + amount, capacity));
     }
   }
+
+  public void shutdown() {
+    scheduler.shutdown();
+  }
 }
diff --git a/rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/AdaptiveRateLimiterTest.java b/rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/AdaptiveRateLimiterTest.java
diff --git a/rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/ConcurrencyTests.java b/rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/ConcurrencyTests.java
diff --git a/single-table-inheritance/src/main/java/com/iluwatar/SingleTableInheritance.java b/single-table-inheritance/src/main/java/com/iluwatar/SingleTableInheritance.java
diff --git a/single-table-inheritance/src/test/java/com/iluwatar/SingleTableInheritanceTest.java b/single-table-inheritance/src/test/java/com/iluwatar/SingleTableInheritanceTest.java

Original file line number	Diff line number	Diff line change
`@@ -43,6 +43,11 @@`
`43`	`43`	`public class App {`
`44`	`44`	`/** Program entry point. */`
`45`	`45`	`public static void main(String[] args) {`
`46`		`- SpringApplication.run(App.class, args);`
	`46`	`+ var context = SpringApplication.run(App.class, args);`
	`47`	`+ if (args.length > 0 && "test".equals(args[0])) {`
	`48`	`+ // Close the context immediately during tests to prevent Tomcat/background threads from`
	`49`	`+ // hanging the JVM`
	`50`	`+ context.close();`
	`51`	`+ }`
`47`	`52`	`}`
`48`	`53`	`}`
Original file line number	Diff line number	Diff line change
`@@ -33,6 +33,6 @@ class AppTest {`
`33`	`33`	`/** Entry point */`
`34`	`34`	`@Test`
`35`	`35`	`void shouldExecuteApplicationWithoutException() {`
`36`		`- assertDoesNotThrow(() -> App.main(new String[] {}));`
	`36`	`+ assertDoesNotThrow(() -> App.main(new String[] {"test"}));`
`37`	`37`	`}`
`38`	`38`	`}`
Original file line number	Diff line number	Diff line change
`@@ -73,6 +73,11 @@ public class Main {`
`73`	`73`	`* @param args command line args`
`74`	`74`	`*/`
`75`	`75`	`public static void main(String[] args) {`
`76`		`- SpringApplication.run(Main.class, args);`
	`76`	`+ var context = SpringApplication.run(Main.class, args);`
	`77`	`+ if (args.length > 0 && "test".equals(args[0])) {`
	`78`	`+ // Close the context immediately during tests to prevent Tomcat/background threads from`
	`79`	`+ // hanging the JVM`
	`80`	`+ context.close();`
	`81`	`+ }`
`77`	`82`	`}`
`78`	`83`	`}`
Original file line number	Diff line number	Diff line change
`@@ -32,6 +32,6 @@`
`32`	`32`	`class MainTest {`
`33`	`33`	`@Test`
`34`	`34`	`void shouldExecuteApplicationWithoutException() {`
`35`		`- assertDoesNotThrow(() -> Main.main(new String[] {}));`
	`35`	`+ assertDoesNotThrow(() -> Main.main(new String[] {"test"}));`
`36`	`36`	`}`
`37`	`37`	`}`
Original file line number	Diff line number	Diff line change
`@@ -72,6 +72,11 @@ public class Main {`
`72`	`72`	`* @param args command line args`
`73`	`73`	`*/`
`74`	`74`	`public static void main(String[] args) {`
`75`		`- SpringApplication.run(Main.class, args);`
	`75`	`+ var context = SpringApplication.run(Main.class, args);`
	`76`	`+ if (args.length > 0 && "test".equals(args[0])) {`
	`77`	`+ // Close the context immediately during tests to prevent Tomcat/background threads from`
	`78`	`+ // hanging the JVM`
	`79`	`+ context.close();`
	`80`	`+ }`
`76`	`81`	`}`
`77`	`82`	`}`
Original file line number	Diff line number	Diff line change
`@@ -33,6 +33,6 @@`
`33`	`33`	`class MainTest {`
`34`	`34`	`@Test`
`35`	`35`	`void shouldExecuteApplicationWithoutException() {`
`36`		`- assertDoesNotThrow(() -> Main.main(new String[] {}));`
	`36`	`+ assertDoesNotThrow(() -> Main.main(new String[] {"test"}));`
`37`	`37`	`}`
`38`	`38`	`}`
Original file line number	Diff line number	Diff line change
`@@ -40,7 +40,7 @@ class AppTest {`
`40`	`40`
`41`	`41`	`@Test`
`42`	`42`	`void testMain() {`
`43`		`- assertDoesNotThrow(() -> App.main(new String[] {}));`
	`43`	`+ assertDoesNotThrow(() -> App.main(new String[] {"test"}));`
`44`	`44`	`}`
`45`	`45`
`46`	`46`	`@Test`