add complete order command handler test

src/Services/Ordering/Ordering.UnitTests/Application/CompleteOrderCommandHandlerTest.cs

@@ -0,0 +1,34 @@
+namespace UnitTest.Ordering.Application;
+
+using Microsoft.eShopOnContainers.Services.Ordering.Domain.AggregatesModel.OrderAggregate;
+
+public class CompleteOrderCommandHandlerTest
+{
+    private readonly Mock<IOrderRepository> _orderRepositoryMock;
+
+    public CompleteOrderCommandHandlerTest()
+    {
+
+        _orderRepositoryMock = new Mock<IOrderRepository>();
+    }
+
+    [Theory]
+    [InlineData(-1)]
+    public async Task Handle_return_false_if_order_is_not_found(int orderId)
+    {
+        var fakeCompleteOrderCommand = FakeCompleteOrderCommand(orderId);
+
+        _orderRepositoryMock.Setup(orderRepo => orderRepo.GetAsync(It.IsAny<int>()))
+            .Returns(Task.FromResult<Order>(null));
+
+        //Act
+        var handler = new CompleteOrderCommandHandler(_orderRepositoryMock.Object);
+
+        var result = await handler.Handle(fakeCompleteOrderCommand, new CancellationToken());
+
+        //Assert
+        Assert.False(result);
+    }
+
+    private CompleteOrderCommand FakeCompleteOrderCommand(int orderId) => new(orderId);
+}