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WeakEventManagerTests.cs
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WeakEventManagerTests.cs
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using System;
using NUnit.Framework;
namespace Xamarin.Forms.Core.UnitTests
{
[TestFixture]
public class WeakEventManagerTests
{
static int s_count;
static void Handler(object sender, EventArgs eventArgs)
{
s_count++;
}
internal class TestSource
{
public int Count = 0;
public TestEventSource EventSource { get; set; }
public TestSource()
{
EventSource = new TestEventSource();
EventSource.TestEvent += EventSource_TestEvent;
}
public void Clean()
{
EventSource.TestEvent -= EventSource_TestEvent;
}
public void Fire()
{
EventSource.FireTestEvent();
}
void EventSource_TestEvent(object sender, EventArgs e)
{
Count++;
}
}
internal class TestEventSource
{
readonly WeakEventManager _weakEventManager;
public TestEventSource()
{
_weakEventManager = new WeakEventManager();
}
public void FireTestEvent()
{
OnTestEvent();
}
internal event EventHandler TestEvent
{
add { _weakEventManager.AddEventHandler(value); }
remove { _weakEventManager.RemoveEventHandler(value); }
}
void OnTestEvent()
{
_weakEventManager.HandleEvent(this, EventArgs.Empty, nameof(TestEvent));
}
}
internal class TestSubscriber
{
public void Subscribe(TestEventSource source)
{
source.TestEvent += SourceOnTestEvent;
}
void SourceOnTestEvent(object sender, EventArgs eventArgs)
{
Assert.Fail();
}
}
[Test]
public void AddHandlerWithEmptyEventNameThrowsException()
{
var wem = new WeakEventManager();
Assert.Throws<ArgumentNullException>(() => wem.AddEventHandler((sender, args) => { }, ""));
}
[Test]
public void AddHandlerWithNullEventHandlerThrowsException()
{
var wem = new WeakEventManager();
Assert.Throws<ArgumentNullException>(() => wem.AddEventHandler(null, "test"));
}
[Test]
public void AddHandlerWithNullEventNameThrowsException()
{
var wem = new WeakEventManager();
Assert.Throws<ArgumentNullException>(() => wem.AddEventHandler((sender, args) => { }, null));
}
[Test]
public void CanRemoveEventHandler()
{
var source = new TestSource();
int beforeRun = source.Count;
source.Fire();
Assert.IsTrue(source.Count == 1);
source.Clean();
source.Fire();
Assert.IsTrue(source.Count == 1);
}
[Test]
public void CanRemoveStaticEventHandler()
{
int beforeRun = s_count;
var source = new TestEventSource();
source.TestEvent += Handler;
source.TestEvent -= Handler;
source.FireTestEvent();
Assert.IsTrue(s_count == beforeRun);
}
[Test]
public void EventHandlerCalled()
{
var called = false;
var source = new TestEventSource();
source.TestEvent += (sender, args) => { called = true; };
source.FireTestEvent();
Assert.IsTrue(called);
}
[Test]
public void FiringEventWithoutHandlerShouldNotThrow()
{
var source = new TestEventSource();
source.FireTestEvent();
}
[Test]
public void MultipleHandlersCalled()
{
var called1 = false;
var called2 = false;
var source = new TestEventSource();
source.TestEvent += (sender, args) => { called1 = true; };
source.TestEvent += (sender, args) => { called2 = true; };
source.FireTestEvent();
Assert.IsTrue(called1 && called2);
}
[Test]
public void RemoveHandlerWithEmptyEventNameThrowsException()
{
var wem = new WeakEventManager();
Assert.Throws<ArgumentNullException>(() => wem.RemoveEventHandler((sender, args) => { }, ""));
}
[Test]
public void RemoveHandlerWithNullEventHandlerThrowsException()
{
var wem = new WeakEventManager();
Assert.Throws<ArgumentNullException>(() => wem.RemoveEventHandler(null, "test"));
}
[Test]
public void RemoveHandlerWithNullEventNameThrowsException()
{
var wem = new WeakEventManager();
Assert.Throws<ArgumentNullException>(() => wem.RemoveEventHandler((sender, args) => { }, null));
}
[Test]
public void RemovingNonExistentHandlersShouldNotThrow()
{
var wem = new WeakEventManager();
wem.RemoveEventHandler((sender, args) => { }, "fake");
wem.RemoveEventHandler(Handler, "alsofake");
}
[Test]
public void RemoveHandlerWithMultipleSubscriptionsRemovesOne()
{
int beforeRun = s_count;
var source = new TestEventSource();
source.TestEvent += Handler;
source.TestEvent += Handler;
source.TestEvent -= Handler;
source.FireTestEvent();
Assert.AreEqual (beforeRun + 1, s_count);
}
[Test]
public void StaticHandlerShouldRun()
{
int beforeRun = s_count;
var source = new TestEventSource();
source.TestEvent += Handler;
source.FireTestEvent();
Assert.IsTrue(s_count > beforeRun);
}
[Test]
public void VerifySubscriberCanBeCollected()
{
WeakReference wr = null;
var source = new TestEventSource();
new Action(() =>
{
var ts = new TestSubscriber();
wr = new WeakReference(ts);
ts.Subscribe(source);
})();
GC.Collect();
GC.WaitForPendingFinalizers();
Assert.IsNotNull(wr);
Assert.IsFalse(wr.IsAlive);
// The handler for this calls Assert.Fail, so if the subscriber has not been collected
// the handler will be called and the test will fail
source.FireTestEvent();
}
}
}