Fix flaky integration test

Closes gh-21487

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/cassandra/CassandraAutoConfigurationWithPasswordAuthenticationIntegrationTests.java

@@ -16,14 +16,21 @@
 
 package org.springframework.boot.autoconfigure.cassandra;
 
+import java.net.InetSocketAddress;
 import java.nio.charset.StandardCharsets;
 import java.time.Duration;
+import java.util.concurrent.TimeUnit;
 
 import com.datastax.oss.driver.api.core.ConsistencyLevel;
 import com.datastax.oss.driver.api.core.CqlSession;
+import com.datastax.oss.driver.api.core.CqlSessionBuilder;
 import com.datastax.oss.driver.api.core.cql.SimpleStatement;
 import org.junit.jupiter.api.Test;
+import org.rnorth.ducttape.TimeoutException;
+import org.rnorth.ducttape.unreliables.Unreliables;
 import org.testcontainers.containers.CassandraContainer;
+import org.testcontainers.containers.ContainerLaunchException;
+import org.testcontainers.containers.wait.strategy.AbstractWaitStrategy;
 import org.testcontainers.images.builder.Transferable;
 import org.testcontainers.junit.jupiter.Container;
 import org.testcontainers.junit.jupiter.Testcontainers;
@@ -45,7 +52,7 @@ class CassandraAutoConfigurationWithPasswordAuthenticationIntegrationTests {
 
 	@Container
 	static final CassandraContainer<?> cassandra = new PasswordAuthenticatorCassandraContainer().withStartupAttempts(5)
-			.withStartupTimeout(Duration.ofMinutes(10));
+			.withStartupTimeout(Duration.ofMinutes(10)).waitingFor(new CassandraWaitStrategy());
 
 	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
 			.withConfiguration(AutoConfigurations.of(CassandraAutoConfiguration.class)).withPropertyValues(
@@ -88,4 +95,29 @@ protected void containerIsCreated(String containerId) {
 
 	}
 
+	static final class CassandraWaitStrategy extends AbstractWaitStrategy {
+
+		@Override
+		protected void waitUntilReady() {
+			try {
+				Unreliables.retryUntilSuccess((int) this.startupTimeout.getSeconds(), TimeUnit.SECONDS, () -> {
+					getRateLimiter().doWhenReady(() -> cqlSessionBuilder().build());
+					return true;
+				});
+			}
+			catch (TimeoutException ex) {
+				throw new ContainerLaunchException(
+						"Timed out waiting for Cassandra to be accessible for query execution");
+			}
+		}
+
+		private CqlSessionBuilder cqlSessionBuilder() {
+			return CqlSession.builder()
+					.addContactPoint(new InetSocketAddress(this.waitStrategyTarget.getHost(),
+							this.waitStrategyTarget.getFirstMappedPort()))
+					.withLocalDatacenter("datacenter1").withAuthCredentials("cassandra", "cassandra");
+		}
+
+	}
+
 }