PowerShell-PowerShell/test/csharp/test_Utils.cs

// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License.
using Xunit;
using System;
using System.Management.Automation;
using System.Management.Automation.Internal;
using System.Reflection;

namespace PSTests.Parallel
{
    public static class UtilsTests
    {
        [SkippableFact]
        public static void TestIsWinPEHost()
        {
            Skip.IfNot(Platform.IsWindows);
            Assert.False(Utils.IsWinPEHost());
        }

        [Fact]
        public static void TestHistoryStack()
        {
            var historyStack = new HistoryStack<string>(20);
            Assert.Equal(0, historyStack.UndoCount);
            Assert.Equal(0, historyStack.RedoCount);

            historyStack.Push("first item");
            historyStack.Push("second item");
            Assert.Equal(2, historyStack.UndoCount);
            Assert.Equal(0, historyStack.RedoCount);

            Assert.Equal("second item", historyStack.Undo("second item"));
            Assert.Equal("first item", historyStack.Undo("first item"));
            Assert.Equal(0, historyStack.UndoCount);
            Assert.Equal(2, historyStack.RedoCount);

            Assert.Equal("first item", historyStack.Redo("first item"));
            Assert.Equal(1, historyStack.UndoCount);
            Assert.Equal(1, historyStack.RedoCount);

            // Pushing a new item should invalidate the RedoCount
            historyStack.Push("third item");
            Assert.Equal(2, historyStack.UndoCount);
            Assert.Equal(0, historyStack.RedoCount);

            // Check for the correct exception when the Redo/Undo stack is empty.
            Assert.Throws<InvalidOperationException>(() => historyStack.Redo("bar"));
            historyStack.Undo("third item");
            historyStack.Undo("first item");
            Assert.Equal(0, historyStack.UndoCount);
            Assert.Throws<InvalidOperationException>(() => historyStack.Undo("foo"));
        }

        [Fact]
        public static void TestBoundedStack()
        {
            uint capacity = 20;
            var boundedStack = new BoundedStack<string>(capacity);
            Assert.Throws<InvalidOperationException>(() => boundedStack.Pop());

            for (int i = 0; i < capacity; i++)
            {
                boundedStack.Push($"{i}");
            }

            for (int i = 0; i < capacity; i++)
            {
                var poppedItem = boundedStack.Pop();
                Assert.Equal($"{20 - 1 - i}", poppedItem);
            }

            Assert.Throws<InvalidOperationException>(() => boundedStack.Pop());
        }
    }
}