#region Apache License 2.0
/*
Nuclex .NET Framework
Copyright (C) 2002-2024 Markus Ewald / Nuclex Development Labs

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

    http://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.
*/
#endregion // Apache License 2.0

using System;
using System.ComponentModel;

using NUnit.Framework;

namespace Nuclex.Support {

  /// <summary>Unit tests for observable class</summary>
  [TestFixture]
  internal class ObservableTest {

    #region class TestObservable

    /// <summary>Example class on which unit test generates change notifications</summary>
    public class TestObservable : Observable {

      /// <summary>Triggers the property changed event for the specified property</summary>
      /// <param name="propertyName">
      ///   Name of the property that will be reported as changed
      /// </param>
      public void FirePropertyChanged(string propertyName) {
        OnPropertyChanged(propertyName);
      }

      /// <summary>Fires the property changed event for the 'SomePropety' property</summary>
      public void FireSomePropertyChanged() {
        #pragma warning disable 0618
        OnPropertyChanged(() => SomeProperty);
        #pragma warning restore 0618
      }

      /// <summary>Example property that will be reported to have changed</summary>
      public int SomeProperty { get; set; }

    }

    #endregion // class TestObservable

    #region class MockedSubscriber

    /// <summary>Mocked change notification subscriber</summary>
    public class MockedSubscriber {

      /// <summary>Called when the value of a property has changed</summary>
      /// <param name="sender">Object of which a property has changed</param>
      /// <param name="arguments">Contains the name of the changed property</param>
      public void PropertyChanged(object sender, PropertyChangedEventArgs arguments) {
        this.wasNotified = true;
        this.changedPropertyName = arguments.PropertyName;
      }

      /// <summary>Whether the subscriber was notified of a property change</summary>
      public bool WasNotified {
        get { return this.wasNotified; }
      }

      /// <summary>
      ///   Checks whether a change notification for the specified property was received
      /// </summary>
      /// <param name="propertyName">Name of the property that will be checked for</param>
      /// <returns>
      ///   True if a change notification for the specified property was received
      /// </returns>
      public bool WasNotifiedOfChangeTo(string propertyName) {
        if(!this.wasNotified) {
          return false;
        }

        if(string.IsNullOrEmpty(propertyName)) {
          return string.IsNullOrEmpty(this.changedPropertyName);
        }

        return (propertyName == this.changedPropertyName);
      }

      /// <summary>Whether a change notification was received</summary>
      private bool wasNotified;
      /// <summary>Name of the property for which a change notification was received</summary>
      private string changedPropertyName;

    }

    #endregion // class MockedSubscriber

    /// <summary>Called before each unit test is run</summary>
    [SetUp]
    public void Setup() {
      this.testObservable = new TestObservable();
      this.subscriber = new MockedSubscriber();

      this.testObservable.PropertyChanged += this.subscriber.PropertyChanged;
    }

    /// <summary>
    ///   Verifies that the name of the changed property can be specified manually
    ///   when triggering the PropertyChanged event
    /// </summary>
    [Test]
    public void PropertyNameCanBeSpecifiedManually() {
      this.testObservable.FirePropertyChanged("SomeProperty");
      Assert.IsTrue(this.subscriber.WasNotifiedOfChangeTo("SomeProperty"));
    }

#if DEBUG // The check is conditionally performed only in debug mode
    /// <summary>
    ///   Verifies that specifying the name of a property that doesn't exist
    ///   causes an ArgumentException to be thrown
    /// </summary>
    [Test]
    public void SpecifyingInvalidPropertyNameThrowsArgumentException() {
      Assert.Throws<ArgumentException>(
        delegate() { this.testObservable.FirePropertyChanged("DoesntExist"); }
      );
    }
#endif

    /// <summary>
    ///   Verifies that the observable is capable of deducing the name of the property
    ///   from a lambda expression
    /// </summary>
    [Test]
    public void PropertyNameCanBeDeducedFromLambdaExpression() {
      this.testObservable.FireSomePropertyChanged();
      Assert.IsTrue(this.subscriber.WasNotifiedOfChangeTo("SomeProperty"));
    }

    /// <summary>
    ///   Verifies that change notifications for all properties of a type can
    ///   be generated
    /// </summary>
    [Test]
    public void WildcardChangeNotificationsCanBeSent() {
      this.testObservable.FirePropertyChanged(string.Empty);
      Assert.IsTrue(this.subscriber.WasNotifiedOfChangeTo(null));

      this.testObservable.FirePropertyChanged(null);
      Assert.IsTrue(this.subscriber.WasNotifiedOfChangeTo(string.Empty));
    }

    /// <summary>Observable object being tested</summary>
    private TestObservable testObservable;
    /// <summary>Subscriber to the observable object being tested</summary>
    private MockedSubscriber subscriber;

  }

} // namespace Nuclex.Support