diff --git a/src/test/java/kiss/TestableScheduler.java b/src/test/java/kiss/TestableScheduler.java
index 997856d46..dc93b80aa 100644
--- a/src/test/java/kiss/TestableScheduler.java
+++ b/src/test/java/kiss/TestableScheduler.java
@@ -9,9 +9,13 @@
  */
 package kiss;
 
+import static java.util.concurrent.TimeUnit.*;
+
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.Callable;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -19,7 +23,7 @@
 
 public class TestableScheduler extends Scheduler {
 
-    private long awaitingLimit = 1000;
+    private long awaitingLimit = 3000;
 
     private final AtomicBoolean starting = new AtomicBoolean();
 
@@ -198,6 +202,111 @@ public boolean awaitExecutions(long required) {
         return true;
     }
 
+    public boolean await() {
+        return start().awaitIdling();
+    }
+
+    /**
+     * Freeze process.
+     */
+    public void await(long time, TimeUnit unit) {
+        freezeNano(unit.toNanos(time));
+    }
+
+    /**
+     * <p>
+     * Freeze process.
+     * </p>
+     * 
+     * @param time A nano time to freeze.
+     */
+    private void freezeNano(long time) {
+        try {
+            long start = System.nanoTime();
+            NANOSECONDS.sleep(time);
+            long end = System.nanoTime();
+
+            long remaining = start + time - end;
+
+            if (0 < remaining) {
+                freezeNano(remaining);
+            }
+        } catch (InterruptedException e) {
+            throw new Error(e);
+        }
+    }
+
+    private long marked;
+
+    /**
+     * Record the current time. Hereafter, it is used as the start time when using
+     * {@link #elapse(int, TimeUnit)} or {@link #within(int, TimeUnit, Runnable)}.
+     */
+    public final TestableScheduler mark() {
+        marked = System.nanoTime();
+
+        return this;
+    }
+
+    /**
+     * <p>
+     * Waits for the specified time from the marked time. It does not wait if it has already passed.
+     * </p>
+     * <pre>
+     * chronus.mark();
+     * asynchronous.process();
+     * 
+     * chronus.elapse(100, TimeUnit.MILLSECONDS);
+     * assert validation.code();
+     * </pre>
+     * 
+     * @param amount Time amount.
+     * @param unit Time unit.
+     */
+    public final TestableScheduler elapse(int amount, TimeUnit unit) {
+        long startTime = marked + unit.toNanos(amount);
+
+        await(startTime - System.nanoTime(), NANOSECONDS);
+
+        return this;
+    }
+
+    /**
+     * <p>
+     * Performs the specified operation if the specified time has not yet elapsed since the marked
+     * time. If it has already passed, do nothing.
+     * </p>
+     * <pre>
+     * chronus.mark();
+     * synchronous.process();
+     * 
+     * chronus.within(100, TimeUnit.MILLSECONDS, () -> {
+     * assert validation.code();
+     * });
+     * </pre>
+     * 
+     * @param amount Time amount.
+     * @param unit Time unit.
+     * @param within Your process.
+     */
+    public final TestableScheduler within(int amount, TimeUnit unit, Runnable within) {
+        if (within != null && System.nanoTime() < marked + unit.toNanos(amount)) {
+            within.run();
+        }
+        return this;
+    }
+
+    /**
+     * Create delayed {@link Executors} in the specified duration.
+     * 
+     * @param time A delay time.
+     * @param unit A time unit.
+     * @return A delayed {@link Executor}.
+     */
+    public Executor in(long time, TimeUnit unit) {
+        return task -> schedule(task, time, unit);
+    }
+
     /**
      * {@inheritDoc}
      */
diff --git a/src/test/java/kiss/signal/OnTest.java b/src/test/java/kiss/signal/OnTest.java
index 4c0b23f35..166f1a452 100644
--- a/src/test/java/kiss/signal/OnTest.java
+++ b/src/test/java/kiss/signal/OnTest.java
@@ -16,6 +16,7 @@
 import org.junit.jupiter.api.Test;
 
 import kiss.I;
+import kiss.TestableScheduler;
 
 class OnTest extends SignalTester {
 
@@ -23,7 +24,8 @@ class OnTest extends SignalTester {
 
     @Test
     void on() {
-        monitor(signal -> signal.on(after).map(v -> Thread.currentThread().getName().contains("pool")));
+        Thread now = Thread.currentThread();
+        monitor(signal -> signal.on(after).map(v -> Thread.currentThread() != now));
 
         main.emit("START");
         assert main.value();
@@ -57,7 +59,7 @@ void complete() {
     void dispose() {
         // Signal#on doesn't guarantee the execution order of events (including COMPLETE)
         // Single thread executor will arrange all events in serial. (FIFO)
-        scheduler.configExecutionLimit(1);
+        scheduler = new TestableScheduler(1);
 
         monitor(signal -> signal.take(1).on(after));
 
diff --git a/src/test/java/kiss/signal/SignalCreationTest.java b/src/test/java/kiss/signal/SignalCreationTest.java
index 2c206a09a..1caea45dc 100644
--- a/src/test/java/kiss/signal/SignalCreationTest.java
+++ b/src/test/java/kiss/signal/SignalCreationTest.java
@@ -143,7 +143,7 @@ void interval() {
         assert main.isNotCompleted();
         assert main.isNotDisposed();
 
-        scheduler.await(200, ms);
+        scheduler.await();
         assert main.value(true, true, true);
         assert main.isCompleted();
         assert main.isDisposed();
diff --git a/src/test/java/kiss/signal/SignalTester.java b/src/test/java/kiss/signal/SignalTester.java
index 03f74b331..4f467efa1 100644
--- a/src/test/java/kiss/signal/SignalTester.java
+++ b/src/test/java/kiss/signal/SignalTester.java
@@ -19,7 +19,6 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.concurrent.CopyOnWriteArrayList;
-import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 import java.util.function.BiFunction;
@@ -28,11 +27,11 @@
 import java.util.function.Supplier;
 import java.util.stream.Stream;
 
-import antibug.Chronus;
 import kiss.Disposable;
 import kiss.I;
 import kiss.Observer;
 import kiss.Signal;
+import kiss.TestableScheduler;
 import kiss.WiseBiFunction;
 import kiss.WiseConsumer;
 import kiss.WiseFunction;
@@ -76,7 +75,7 @@ public class SignalTester {
     protected final SignalSource another = new SignalSource();
 
     /** The chrono scheduler. */
-    protected final Chronus scheduler = new Chronus(() -> Executors.newScheduledThreadPool(16));
+    protected TestableScheduler scheduler = new TestableScheduler();
 
     /** The log manager. */
     private Map<String, List> logs;