feat: add basic Desireset wrapper (#29)

* feat: add DesireSet

* docs: add code documentation

* feat: add UpdateStatus to DesireSet

* test: add DesireSet tests

* fix: add in keyword and fix xml comment

* chore: remove redundant using directive

* refactor: use expression body definition

Aplib.Core/Desire/DesireSet.cs

@@ -0,0 +1,33 @@
+using Aplib.Core.Belief;
+using Aplib.Core.Desire.Goals;
+
+namespace Aplib.Core.Desire
+{
+    /// <inheritdoc />
+    public class DesireSet<TBeliefSet> : IDesireSet<TBeliefSet>
+        where TBeliefSet : IBeliefSet
+    {
+        /// <summary>
+        /// Stores the main goal structure of the agent.
+        /// </summary>
+        private IGoalStructure<TBeliefSet> _mainGoal { get; }
+
+        /// <inheritdoc />
+        public CompletionStatus Status => _mainGoal.Status;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DesireSet{TBeliefSet}" /> class.
+        /// </summary>
+        /// <param name="mainGoal">The main goal structure that the agent needs to complete.</param>
+        public DesireSet(IGoalStructure<TBeliefSet> mainGoal) 
+            => _mainGoal = mainGoal;
+
+        /// <inheritdoc />
+        public IGoal GetCurrentGoal(TBeliefSet beliefSet)
+            => _mainGoal.GetCurrentGoal(beliefSet);
+
+        /// <inheritdoc />
+        public void UpdateStatus(TBeliefSet beliefSet)
+            => _mainGoal.UpdateStatus(beliefSet);
+    }
+}

Aplib.Core/Desire/IDesireSet.cs

@@ -0,0 +1,27 @@
+using Aplib.Core.Belief;
+using Aplib.Core.Desire.Goals;
+
+namespace Aplib.Core.Desire
+{
+    /// <summary>
+    /// Represents a set of goals that the agent has.
+    /// This is the main structure that the agent will use to determine what it should do next.
+    /// </summary>
+    /// <typeparam name="TBeliefSet"></typeparam>
+    public interface IDesireSet<in TBeliefSet> : ICompletable
+        where TBeliefSet : IBeliefSet
+    {
+        /// <summary>
+        /// Gets the current goal using the given <see cref="IBeliefSet" />.
+        /// </summary>
+        /// <param name="beliefSet">The belief set of the agent.</param>
+        /// <returns>The current goal to be fulfilled.</returns>
+        IGoal GetCurrentGoal(TBeliefSet beliefSet);
+
+        /// <summary>
+        /// Updates the status of this <see cref="IDesireSet{TBeliefSet}"/>.
+        /// </summary>
+        /// <param name="beliefSet">The belief set of the agent.</param>
+        void UpdateStatus(TBeliefSet beliefSet);
+    }
+}

Aplib.Tests/Core/Desire/DesireSetTests.cs

@@ -0,0 +1,75 @@
+using Aplib.Core;
+using Aplib.Core.Belief;
+using Aplib.Core.Desire;
+using Aplib.Core.Desire.Goals;
+using FluentAssertions;
+using Moq;
+
+namespace Aplib.Tests.Core.Desire;
+
+public class DesireSetTests
+{
+    /// <summary>
+    /// Given a desire set,
+    /// When the GetCurrentGoal method is called,
+    /// Then the desire set should return the current goal of the current goal structure.
+    /// </summary>
+    [Fact]
+    public void DesireSet_WhenGetCurrentGoalIsCalled_ReturnsCurrentGoal()
+    {
+        // Arrange
+        IBeliefSet beliefSet = Mock.Of<IBeliefSet>();
+        IGoal goal = Mock.Of<IGoal>();
+        Mock<IGoalStructure<IBeliefSet>> goalStructure = new();
+        goalStructure
+            .Setup(g => g.GetCurrentGoal(It.IsAny<IBeliefSet>()))
+            .Returns(goal);
+        Mock<DesireSet<IBeliefSet>> desireSet = new(goalStructure.Object);
+
+        // Act
+        IGoal currentGoal = desireSet.Object.GetCurrentGoal(beliefSet);
+
+        // Assert
+        currentGoal.Should().Be(goal);
+    }
+
+    /// <summary>
+    /// Given a desire set,
+    /// When the status is updated,
+    /// Then the status of the goal structures are updated.
+    /// </summary>
+    [Fact]
+    public void DesireSet_WhenStatusUpdated_ShouldUpdateGoalStructuresStatus()
+    {
+        // Arrange
+        Mock<IGoalStructure<IBeliefSet>> goalStructure = new();
+        Mock<DesireSet<IBeliefSet>> desireSet = new(goalStructure.Object);
+
+        // Act
+        desireSet.Object.UpdateStatus(It.IsAny<IBeliefSet>());
+
+        // Assert
+        goalStructure.Verify(g => g.UpdateStatus(It.IsAny<IBeliefSet>()), Times.Once());
+    }
+
+    /// <summary>
+    /// Given a desire set,
+    /// When the status is checked,
+    /// Then the status should be the same as the main goal structure status.
+    /// </summary>
+    [Fact]
+    public void DesireSet_WhenStatusIsChecked_ShouldBeSameAsMainGoal()
+    {
+        // Arrange
+        Mock<IGoalStructure<IBeliefSet>> goalStructure = new();
+        goalStructure.Setup(g => g.Status).Returns(CompletionStatus.Success);
+        Mock<DesireSet<IBeliefSet>> desireSet = new(goalStructure.Object);
+
+        // Act
+        CompletionStatus status = desireSet.Object.Status;
+        CompletionStatus expectedStatus = goalStructure.Object.Status;
+
+        // Assert
+        status.Should().Be(expectedStatus);
+    }
+}