Introduce NoOpTaskScheduler for test setups

Closes gh-28073

Author: jhoeller

spring-context/src/main/java/org/springframework/scheduling/support/NoOpTaskScheduler.java

@@ -0,0 +1,112 @@
+/*
+ * Copyright 2002-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.scheduling.support;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.util.concurrent.CancellationException;
+import java.util.concurrent.Delayed;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
+
+import org.springframework.lang.Nullable;
+import org.springframework.scheduling.TaskScheduler;
+import org.springframework.scheduling.Trigger;
+
+/**
+ * A basic, no operation {@link TaskScheduler} implementation suitable
+ * for disabling scheduling, typically used for test setups.
+ *
+ * <p>Will accept any scheduling request but never actually execute it.
+ *
+ * @author Juergen Hoeller
+ * @since 6.1.3
+ */
+public class NoOpTaskScheduler implements TaskScheduler {
+
+	@Override
+	@Nullable
+	public ScheduledFuture<?> schedule(Runnable task, Trigger trigger) {
+		Instant nextExecution = trigger.nextExecution(new SimpleTriggerContext(getClock()));
+		return (nextExecution != null ? new NoOpScheduledFuture<>() : null);
+	}
+
+	@Override
+	public ScheduledFuture<?> schedule(Runnable task, Instant startTime) {
+		return new NoOpScheduledFuture<>();
+	}
+
+	@Override
+	public ScheduledFuture<?> scheduleAtFixedRate(Runnable task, Instant startTime, Duration period) {
+		return new NoOpScheduledFuture<>();
+	}
+
+	@Override
+	public ScheduledFuture<?> scheduleAtFixedRate(Runnable task, Duration period) {
+		return new NoOpScheduledFuture<>();
+	}
+
+	@Override
+	public ScheduledFuture<?> scheduleWithFixedDelay(Runnable task, Instant startTime, Duration delay) {
+		return new NoOpScheduledFuture<>();
+	}
+
+	@Override
+	public ScheduledFuture<?> scheduleWithFixedDelay(Runnable task, Duration delay) {
+		return new NoOpScheduledFuture<>();
+	}
+
+
+	private static class NoOpScheduledFuture<V> implements ScheduledFuture<V> {
+
+		@Override
+		public boolean cancel(boolean mayInterruptIfRunning) {
+			return true;
+		}
+
+		@Override
+		public boolean isCancelled() {
+			return true;
+		}
+
+		@Override
+		public boolean isDone() {
+			return true;
+		}
+
+		@Override
+		public V get() {
+			throw new CancellationException("No-op");
+		}
+
+		@Override
+		public V get(long timeout, TimeUnit unit) {
+			throw new CancellationException("No-op");
+		}
+
+		@Override
+		public long getDelay(TimeUnit unit) {
+			return 0;
+		}
+
+		@Override
+		public int compareTo(Delayed other) {
+			return 0;
+		}
+	}
+
+}