server/protocols/protocols-imap4/src/test/java/org/apache/james/imapserver/netty/LinearalizerTest.java

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package org.apache.james.imapserver.netty;

import static org.assertj.core.api.Assertions.assertThat;

import java.time.Duration;
import java.util.concurrent.atomic.AtomicBoolean;

import org.junit.jupiter.api.Test;
import org.testcontainers.shaded.org.awaitility.Awaitility;

import reactor.core.publisher.Mono;

class LinearalizerTest {
    @Test
    void shouldExecuteSubmittedTasks() {
        Linearalizer testee = new Linearalizer();

        // When I submit a task
        AtomicBoolean executed = new AtomicBoolean(false);
        Mono.from(testee.execute(Mono.delay(Duration.ofMillis(50)).then(Mono.fromRunnable(() -> executed.getAndSet(true))))).block();

        // Then that task is executed
        assertThat(executed.get()).isTrue();
    }

    @Test
    void shouldNotExecuteQueuedTasksLogicRightAway() {
        Linearalizer testee = new Linearalizer();

        // When I submit 2 tasks task
        AtomicBoolean executed = new AtomicBoolean(false);
        Mono.from(testee.execute(Mono.delay(Duration.ofMillis(200)).then())).subscribe();
        Mono.from(testee.execute(Mono.fromRunnable(() -> executed.getAndSet(true)))).subscribe();

        // Then the second task is not executed staight away
        assertThat(executed.get()).isFalse();
    }

    @Test
    void shouldEventuallyExecuteQueuedTasks() {
        Linearalizer testee = new Linearalizer();

        // When I submit 2 tasks task
        AtomicBoolean executed = new AtomicBoolean(false);
        Mono.from(testee.execute(Mono.delay(Duration.ofMillis(200)).then())).subscribe();
        Mono.from(testee.execute(Mono.fromRunnable(() -> executed.getAndSet(true)))).subscribe();

        // Then that task is eventually executed
        Awaitility.await().atMost(Duration.ofSeconds(10))
            .untilAsserted(() -> assertThat(executed.get()).isTrue());
    }
}