DateTimes Formatting / Serializing Issue

[JoshHariz]

Describe the bug

When datetimes are serialized, they are using the below format which is not ISO 8601 as the docs say.

Output:

    "DateCreated": "2025-04-16 23:50:34.0967133 Utc",
    "MessageDate": "2025-03-27 16:04:50.129 Utc",

Verify Settings:

[ModuleInitializer]
public static void Initialize()
{
    // Formats test failure messages
    VerifyDiffPlex.Initialize(VerifyTests.DiffPlex.OutputType.Compact); 

    // Saves all Verify result files in a results directory
    Verifier.UseSourceFileRelativeDirectory("Results");
}

Version:

		<PackageReference Include="Verify" Version="29.2.0" />
		<PackageReference Include="Verify.DiffPlex" Version="3.1.2" />
		<PackageReference Include="Verify.XunitV3" Version="29.2.0" />

Minimum Repro:

Input

return Verify(DateTime.Now)
    .DontScrubDateTimes()
    .UseStrictJson();

Expected Output:
2025-04-17T00:41:27.7349436Z

Actual Output
2025-04-17 00:41:27.7349436 Utc

I dont think I'm doing anything outside of the defaults so should be trivial to replicate. If I'm missing something please let me know.

Thanks!

[SimonCropp]

where do the docs say ISO 8601?

[JoshHariz]

I've been looking deep into the docs trying to understand the datetime serialization and I think I assumed it was all from Verify. It appears that the exact statement I was thinking of is from Argon.

Argon is referenced often in spots like
https://github.com/VerifyTests/Verify/blob/main/docs/serializer-settings.md#default-settings
https://github.com/VerifyTests/Verify/blob/main/docs/serializer-settings.md#serializer-settings

And the Argon docs say that it uses ISO-8601
https://github.com/SimonCropp/Argon/blob/main/docs/DatesInJSON.md

So by inference I figured it would be the same, but I guess that was my mistake. Either way I've figured out the TreatAsString method and got that working to format the datetimes in ISO-8601 :)

Here's the code I got working if anyone faces the same issue as me in the future

VerifierSettings.TreatAsString<DateTime>((date, _) => JsonSerializer.Serialize(date));
VerifierSettings.TreatAsString<DateTimeOffset>((date, _) => JsonSerializer.Serialize(date));

return Verify(DateTimeOffset.Now.ToOffset(TimeSpan.FromHours(9.5)))
    .DontScrubDateTimes()
    .UseStrictJson();

[JoshHariz]

Wait I take it back it isn't resolved, the TreatAsString works fine when I pass it just a DateTime but when I have an object which contains a datetime it doesnt work.

Setup

VerifierSettings.TreatAsString<DateTime>((date, _) => JsonSerializer.Serialize(date));
VerifierSettings.TreatAsString<DateTimeOffset>((date, _) => JsonSerializer.Serialize(date));

// actualSentMessage is an object which contains datetimes with path actualSentMessage.Metadata.DateCreated
await Verify(actualSentMessage)
    .UseFileName($"{Path.GetFileNameWithoutExtension(source)}_Canonical")
    .DontScrubDateTimes()
    .DontScrubGuids()
    .UseStrictJson();

Expected Output

    "DateCreated": "2025-04-17T03:52:20.83734Z",
    "MessageDate": "2025-03-27T16:04:50.129Z",

Actual Output

    "DateCreated": "2025-04-17 03:52:20.83734 Utc",
    "MessageDate": "2025-03-27 16:04:50.129 Utc",

[SimonCropp]

does this explain it https://github.com/VerifyTests/Verify/blob/main/docs/type-to-string-mapping.md ?

[SimonCropp]

And the Argon docs say that it uses ISO-8601

Verify has custom serialization for dates

[SimonCropp]

out of curiosity why do u not want to scrub those datetimes? dont they change every time the test runs

if they are consistent, perhaps the Named Date and Times feature would make more sense https://github.com/VerifyTests/Verify/blob/main/docs/dates.md#named-date-and-times

[JoshHariz]

I see so TreatAsString only works for when you directly pass a datetime in, it doesnt work for properties.

So is there no way to set the ISO format for the output?

The reason I'd like to do this is so that we can take the outputs of some tests and use it to test/debug other parts of our system. Currently we have to manually fixup the dates to valid json before they can be used. I have Explicit tests which are only run to retrieve the output, we scrub the datetimes for our standard tests.

[SimonCropp]

can u share the full code of one of your explicit tests?

[SimonCropp]

bump

[JoshHariz]

Apologies, been away over the Easter weekend. Here is a sample, nothing too fancy.

/// <summary>
/// This test will generate a working canonical that can be used for testing the target-side system. The date formats will need to be slightly modified to work.
/// </summary>
/// <param name="source"></param>
/// <returns></returns>
[Theory(DisplayName = "", Explicit = true)]
//[MemberData(nameof(ValidPayloads))]
[InlineData(TestInputs.CompGradeChange)]
public async Task CreateWorkingCanonical(string source)
{
    // Arrange
    EnvelopeCanonical? actualSentMessage = null;
    // Custom class
    Mock<IMessageManager> messageManagerMock = new();
    messageManagerMock.Setup(
        x => x.SendToTopic(It.IsAny<EnvelopeCanonical>())
        .Callback<EnvelopeCanonical>(
            message => actualSentMessage = message);

    var inputRequest = TestDataFactory.CreateHttpRequest(TestInputs.ReadFile(source));

    // Act
    await payrollFunction.Run(inputRequest);

    // Assert
    await Verify(actualSentMessage)
        .UseFileName($"{Path.GetFileNameWithoutExtension(source)}_Canonical")
        .DontScrubDateTimes()
        .DontScrubGuids()
        .UseStrictJson();
}

[SimonCropp]

IMO you should use this approach

[Theory(DisplayName = "", Explicit = true)]
//[MemberData(nameof(ValidPayloads))]
[InlineData(TestInputs.CompGradeChange)]
public async Task CreateWorkingCanonical(string source)
{
    // Arrange
    EnvelopeCanonical? actualSentMessage = null;
    // Custom class
    Mock<IMessageManager> messageManagerMock = new();
    messageManagerMock.Setup(
        x => x.SendToTopic(It.IsAny<EnvelopeCanonical>())
        .Callback<EnvelopeCanonical>(
            message => actualSentMessage = message);

    var inputRequest = TestDataFactory.CreateHttpRequest(TestInputs.ReadFile(source));

    // Act
    await payrollFunction.Run(inputRequest);

    string json = System.Text.Json.JsonSerializer.Serialize(actualSentMessage);

    // Assert
    await Verify(json)
        .UseFileName($"{Path.GetFileNameWithoutExtension(source)}_Canonical");
}

[JoshHariz]

Thanks very much that seems to meet my requirements. Appreciate your help and you shining some light in this area :)

[SimonCropp]

glad u found a way forward