Snapshot Testing

using System.Runtime.CompilerServices;
public static class ModuleInitializer{    [ModuleInitializer]    public static void Init()    {        // Use source-file-relative paths for verified files        VerifyBase.UseProjectRelativeDirectory("Snapshots");
        // Configure diff tool (optional - auto-detected)        // DiffTools.UseOrder(DiffTool.Rider, DiffTool.VisualStudioCode);    }}

[Fact]public Task VerifyUserDto(){    var user = new UserDto(        Id: "user-123",        Name: "John Doe",        Email: "[email protected]",        CreatedAt: new DateTime(2025, 1, 15));
    return Verify(user);}

[Fact]public async Task VerifyRenderedEmail(){    var html = await _emailRenderer.RenderAsync("Welcome", new { Name = "John" });
    // Use extension parameter for proper file naming    await Verify(html, extension: "html");}

[Fact]public async Task UserSignupInvitation_RendersCorrectly(){    var renderer = _services.GetRequiredService<IMjmlTemplateRenderer>();
    var variables = new Dictionary<string, string>    {        { "OrganizationName", "Acme Corporation" },        { "InviteeName", "John Doe" },        { "InviterName", "Jane Admin" },        { "InvitationLink", "https://example.com/invite/abc123" },        { "ExpirationDate", "December 31, 2025" }    };
    var html = await renderer.RenderTemplateAsync(        "UserInvitations/UserSignupInvitation",        variables);
    await Verify(html, extension: "html");}

[Fact]public Task ApprovePublicApi(){    var assembly = typeof(MyLibrary.PublicClass).Assembly;
    var publicApi = assembly.GetExportedTypes()        .OrderBy(t => t.FullName)        .Select(t => new        {            Type = t.FullName,            Members = t.GetMembers(BindingFlags.Public | BindingFlags.Instance | BindingFlags.Static)                .Where(m => m.DeclaringType == t)                .OrderBy(m => m.Name)                .Select(m => m.ToString())        });
    return Verify(publicApi);}

[Fact]public Task ApproveApi(){    var api = typeof(MyPublicClass).Assembly.GeneratePublicApi();    return Verify(api);}

[Fact]public async Task GetUser_ReturnsExpectedResponse(){    var client = _factory.CreateClient();
    var response = await client.GetAsync("/api/users/123");
    // Verify status, headers, and body together    await Verify(new    {        StatusCode = response.StatusCode,        Headers = response.Headers            .Where(h => h.Key.StartsWith("X-"))  // Custom headers only            .ToDictionary(h => h.Key, h => h.Value.First()),        Body = await response.Content.ReadAsStringAsync()    });}

[Fact]public Task VerifyOrder(){    var order = new Order    {        Id = Guid.NewGuid(),  // Different every run        CreatedAt = DateTime.UtcNow,  // Different every run        Total = 99.99m    };
    return Verify(order)        .ScrubMember("Id")  // Replace with placeholder        .ScrubMember("CreatedAt");}

[ModuleInitializer]public static void Init(){    VerifierSettings.ScrubMembersWithType<DateTime>();    VerifierSettings.ScrubMembersWithType<DateTimeOffset>();    VerifierSettings.ScrubMembersWithType<Guid>();
    // Scrub specific patterns    VerifierSettings.AddScrubber(s =>        Regex.Replace(s, @"token=[a-zA-Z0-9]+", "token=SCRUBBED"));}

[ModuleInitializer]public static void Init(){    // In CI, fail instead of launching diff tool    if (Environment.GetEnvironmentVariable("CI") == "true")    {        VerifyDiffPlex.UseDiffPlex(OutputType.Minimal);        DiffRunner.Disabled = true;    }}

// Use descriptive test names - they become file names[Fact]public Task UserRegistration_WithValidData_ReturnsConfirmation()
// Scrub dynamic values consistentlyVerifierSettings.ScrubMembersWithType<Guid>();
// Use extension parameter for non-text contentawait Verify(html, extension: "html");
// Keep verified files in source controlgit add *.verified.*

// Don't verify random/dynamic data without scrubbingvar order = new Order { Id = Guid.NewGuid() };  // Fails every run!await Verify(order);
// Don't commit .received filesgit add *.received.*  // Wrong!
// Don't use for simple assertionsawait Verify(result.Count);  // Just use Assert.Equal(5, result.Count)