using System;
using NUnit.Framework;

namespace Chernobyl.Switch
{
    /// <summary>
    /// A set of tests for testing types which implement the 
    /// <see cref="ISwitch"/> interface.
    /// </summary>
    public abstract class SwitchTests<TSwitch> where TSwitch : ISwitch
    {
        [Test, Description("A test which ensures the ISwitch.SwitchedOn event " +
            "is properly fired.")]
        public void SwitchedOnTest()
        {
            TSwitch testSwitch = CreateSwitch();
            testSwitch.SwitchedOn += (sender, e) => Assert.Pass();
            FireSwitchedOnEvent(testSwitch);
            Assert.Fail("The ISwitch.SwitchedOn event did not get fired.");
        }

        [Test, Description("A test which ensures the ISwitch.SwitchedOff event " +
                    "is properly fired.")]
        public void SwitchedOffTest()
        {
            TSwitch testSwitch = CreateSwitch();
            testSwitch.SwitchedOff += (sender, e) => Assert.Pass();
            FireSwitchedOffEvent(testSwitch);
            Assert.Fail("The ISwitch.SwitchedOff event did not get fired.");
        }

        [Test, Description("A test which ensures the Reset() method properly " +
            "handles the firing of ISwitch.SwitchedOff event.")]
        public void ResetTest()
        {
            TSwitch testSwitch = CreateSwitch();
            testSwitch.SwitchedOff += (sender, e) => Assert.Pass();
            testSwitch.Reset();
            Assert.Fail("The ISwitch.SwitchedOff event did not get fired.");
        }

        [Test, Description("A test which ensures the reset(object, EventArgs) " +
            "method properly handles firing of ISwitch.SwitchedOff event.")]
        public void ResetEventHandlerTest()
        {
            TSwitch testSwitch = CreateSwitch();
            testSwitch.SwitchedOff += (sender, e) => Assert.Pass();
            testSwitch.Reset(this, EventArgs.Empty);
            Assert.Fail("The ISwitch.SwitchedOff event did not get fired.");
        }

        /// <summary>
        /// Creates the <see cref="ISwitch"/> that should be tested. This method
        /// should always return a new <see cref="ISwitch"/> and never reuse
        /// instances.
        /// </summary>
        /// <returns>The new <see cref="ISwitch"/> to test.</returns>
        protected abstract TSwitch CreateSwitch();

        /// <summary>
        /// Fires the <see cref="ISwitch.SwitchedOn"/> event on the 
        /// <see cref="ISwitch"/> passed in. This method should fire the event
        /// through normally means that would occur in a client application.
        /// </summary>
        /// <param name="testSwitch">The <see cref="ISwitch"/> whose 
        /// <see cref="ISwitch.SwitchedOn"/> should be fired.</param>
        protected abstract void FireSwitchedOnEvent(TSwitch testSwitch);

        /// <summary>
        /// Fires the <see cref="ISwitch.SwitchedOn"/> event on the 
        /// <see cref="ISwitch"/> passed in. This method should fire the event
        /// through normally means that would occur in a client application.
        /// </summary>
        /// <param name="testSwitch">The <see cref="ISwitch"/> whose 
        /// <see cref="ISwitch.SwitchedOn"/> should be fired.</param>
        protected abstract void FireSwitchedOffEvent(TSwitch testSwitch);
    }
}