SyntaxLogicalInverterTests.cs

using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Text;
using Xunit;

namespace Roslynator.CSharp.Workspaces.Tests;

public class SyntaxLogicallyInvertTests
{
    private SyntaxLogicalInverter _inverter;

    public SyntaxLogicallyInvertTests()
    {
        _inverter = SyntaxLogicalInverter.Default;
    }

    [Theory]
    [InlineData(@"x", @"!x")]
    [InlineData(@"!x", @"x")]
    [InlineData(@"x is ""abc""", @"x is not ""abc""")]
    [InlineData(@"x is 1", @"x is not 1")]
    [InlineData(@"x is null", @"x is not null")]
    [InlineData(@"x is true", @"x is false")]
    [InlineData(@"true", @"false")]
    [InlineData(@"false", @"true")]
    [InlineData(@"x >= 3", @"x < 3")]
    [InlineData(@"x > 3", @"x <= 3")]
    [InlineData(@"x <= 3", @"x > 3")]
    [InlineData(@"x < 3", @"x >= 3")]
    [InlineData(@"x == y", @"x != y")]
    [InlineData(@"x != y", @"x == y")]
    [InlineData(@"(bool)x || (bool)y", @"!((bool)x) && !((bool)y)")]
    [InlineData(@"(bool)x && (bool)y", @"!((bool)x) || !((bool)y)")]
    [InlineData(@"x ?? true", @"x == false")]
    [InlineData(@"x ?? false", @"x != true")]
    [InlineData(@"(bool)x ? y : z", @"(bool)x ? !y : !z")]
    [InlineData(@"x[0]", @"!x[0]")]
    [InlineData(@"default(bool)", @"!default(bool)")]
    [InlineData(@"checked(x + y)", @"!checked(x + y)")]
    [InlineData(@"unchecked(x + y)", @"!unchecked(x + y)")]
    [InlineData(@"(bool)x", @"!((bool)x)")]
    [InlineData(@"x & y", @"!x | !y")]
    [InlineData(@"x ^ y", @"!(x ^ y)")]
    [InlineData(@"x | y", @"!x & !y")]
    [InlineData(@"x = y", @"!(x = y)")]
    [InlineData(@"await x", @"!(await x)")]
    [InlineData(@"x ?? y", @"!(x ?? y)")]
    [InlineData(@"x.a", @"!x.a")]
    [InlineData(@"x.a()", @"!x.a()")]
    [InlineData(@"x?.a", @"!x?.a")]
    public async Task LogicallyInvert(string source, string expected)
    {
        var sourceCode = $"class C {{ void M(dynamic x, dynamic y, dynamic z){{ if({source})return;}} }}";
        var workspace = new AdhocWorkspace();
        var newProject = workspace.AddProject("TestProject", LanguageNames.CSharp);
        var newDocument = workspace.AddDocument(newProject.Id, "TestDocument.cs", SourceText.From(sourceCode));
        var syntaxTree = await newDocument.GetSyntaxTreeAsync();
        var compilation = await newDocument.Project.GetCompilationAsync();
        var semanticModel = compilation.GetSemanticModel(syntaxTree);

        var expression = syntaxTree.GetRoot().DescendantNodes().OfType<IfStatementSyntax>().Single().Condition;

        var result = _inverter.LogicallyInvert(expression, semanticModel, CancellationToken.None);
        Assert.Equal(expected, result.NormalizeWhitespace().ToFullString());
    }

}