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Merged
SimonCropp merged 1 commit into from
Aug 17, 2026
Merged

Use ticks to decide date precision #1856

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38 changes: 24 additions & 14 deletions docs/type-to-string-mapping.md
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Original file line number Diff line number Diff line change
Expand Up @@ -146,17 +146,20 @@ public static partial class DateFormatter

static string GetJsonDatePart(DateTime value)
{
if (value.TimeOfDay == TimeSpan.Zero)
// ticks, not the Second/Millisecond properties, since sub-millisecond ticks leave both of those zero
var ticks = value.TimeOfDay.Ticks;

if (ticks == 0)
{
return value.ToString("yyyy-MM-dd", Culture.InvariantCulture);
}

if (value is {Second: 0, Millisecond: 0})
if (ticks % TimeSpan.TicksPerMinute == 0)
{
return value.ToString("yyyy-MM-dd HH:mm", Culture.InvariantCulture);
}

if (value.Millisecond == 0)
if (ticks % TimeSpan.TicksPerSecond == 0)
{
return value.ToString("yyyy-MM-dd HH:mm:ss", Culture.InvariantCulture);
}
Expand All @@ -178,17 +181,19 @@ public static partial class DateFormatter

static string GetParameterDatePart(DateTime value)
{
if (value.TimeOfDay == TimeSpan.Zero)
var ticks = value.TimeOfDay.Ticks;

if (ticks == 0)
{
return value.ToString("yyyy-MM-dd", Culture.InvariantCulture);
}

if (value is {Second: 0, Millisecond: 0})
if (ticks % TimeSpan.TicksPerMinute == 0)
{
return value.ToString("yyyy-MM-ddTHH-mm", Culture.InvariantCulture);
}

if (value.Millisecond == 0)
if (ticks % TimeSpan.TicksPerSecond == 0)
{
return value.ToString("yyyy-MM-ddTHH-mm-ss", Culture.InvariantCulture);
}
Expand All @@ -197,7 +202,7 @@ public static partial class DateFormatter
}
}
```
<sup><a href='/src/Verify/Serialization/DateFormatter_DateTime.cs#L1-L68' title='Snippet source file'>snippet source</a> | <a href='#snippet-DateFormatter_DateTime.cs' title='Start of snippet'>anchor</a></sup>
<sup><a href='/src/Verify/Serialization/DateFormatter_DateTime.cs#L1-L73' title='Snippet source file'>snippet source</a> | <a href='#snippet-DateFormatter_DateTime.cs' title='Start of snippet'>anchor</a></sup>
<!-- endSnippet -->


Expand All @@ -221,17 +226,20 @@ public static partial class DateFormatter

static string GetJsonDatePart(DateTimeOffset value)
{
if (value.TimeOfDay == TimeSpan.Zero)
// ticks, not the Second/Millisecond properties, since sub-millisecond ticks leave both of those zero
var ticks = value.TimeOfDay.Ticks;

if (ticks == 0)
{
return value.ToString("yyyy-MM-dd", Culture.InvariantCulture);
}

if (value is {Second: 0, Millisecond: 0})
if (ticks % TimeSpan.TicksPerMinute == 0)
{
return value.ToString("yyyy-MM-dd HH:mm", Culture.InvariantCulture);
}

if (value.Millisecond == 0)
if (ticks % TimeSpan.TicksPerSecond == 0)
{
return value.ToString("yyyy-MM-dd HH:mm:ss", Culture.InvariantCulture);
}
Expand All @@ -249,17 +257,19 @@ public static partial class DateFormatter

static string GetParameterDatePart(DateTimeOffset value)
{
if (value.TimeOfDay == TimeSpan.Zero)
var ticks = value.TimeOfDay.Ticks;

if (ticks == 0)
{
return value.ToString("yyyy-MM-dd", Culture.InvariantCulture);
}

if (value is {Second: 0, Millisecond: 0})
if (ticks % TimeSpan.TicksPerMinute == 0)
{
return value.ToString("yyyy-MM-ddTHH-mm", Culture.InvariantCulture);
}

if (value.Millisecond == 0)
if (ticks % TimeSpan.TicksPerSecond == 0)
{
return value.ToString("yyyy-MM-ddTHH-mm-ss", Culture.InvariantCulture);
}
Expand Down Expand Up @@ -295,7 +305,7 @@ public static partial class DateFormatter
}
}
```
<sup><a href='/src/Verify/Serialization/DateFormatter_DateTimeOffset.cs#L1-L86' title='Snippet source file'>snippet source</a> | <a href='#snippet-DateFormatter_DateTimeOffset.cs' title='Start of snippet'>anchor</a></sup>
<sup><a href='/src/Verify/Serialization/DateFormatter_DateTimeOffset.cs#L1-L91' title='Snippet source file'>snippet source</a> | <a href='#snippet-DateFormatter_DateTimeOffset.cs' title='Start of snippet'>anchor</a></sup>
<!-- endSnippet -->


Expand Down
50 changes: 50 additions & 0 deletions src/Verify.Tests/DateFormatterTests.SubMillisecondTicks.verified.txt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,50 @@
{
0: {
dateJson: 2000-10-01 Utc,
dateParameter: 2000-10-01Utc,
offsetJson: 2000-10-01 +0,
offsetParameter: 2000-10-01+0
},
1: {
dateJson: 2000-10-01 00:00:00.0000001 Utc,
dateParameter: 2000-10-01T00-00-00.0000001Utc,
offsetJson: 2000-10-01 00:00:00.0000001 +0,
offsetParameter: 2000-10-01T00-00-00.0000001+0
},
10000: {
dateJson: 2000-10-01 00:00:00.001 Utc,
dateParameter: 2000-10-01T00-00-00.001Utc,
offsetJson: 2000-10-01 00:00:00.001 +0,
offsetParameter: 2000-10-01T00-00-00.001+0
},
10000000: {
dateJson: 2000-10-01 00:00:01 Utc,
dateParameter: 2000-10-01T00-00-01Utc,
offsetJson: 2000-10-01 00:00:01 +0,
offsetParameter: 2000-10-01T00-00-01+0
},
10000001: {
dateJson: 2000-10-01 00:00:01.0000001 Utc,
dateParameter: 2000-10-01T00-00-01.0000001Utc,
offsetJson: 2000-10-01 00:00:01.0000001 +0,
offsetParameter: 2000-10-01T00-00-01.0000001+0
},
2: {
dateJson: 2000-10-01 00:00:00.0000002 Utc,
dateParameter: 2000-10-01T00-00-00.0000002Utc,
offsetJson: 2000-10-01 00:00:00.0000002 +0,
offsetParameter: 2000-10-01T00-00-00.0000002+0
},
600000000: {
dateJson: 2000-10-01 00:01 Utc,
dateParameter: 2000-10-01T00-01Utc,
offsetJson: 2000-10-01 00:01 +0,
offsetParameter: 2000-10-01T00-01+0
},
600000001: {
dateJson: 2000-10-01 00:01:00.0000001 Utc,
dateParameter: 2000-10-01T00-01-00.0000001Utc,
offsetJson: 2000-10-01 00:01:00.0000001 +0,
offsetParameter: 2000-10-01T00-01-00.0000001+0
}
}
49 changes: 49 additions & 0 deletions src/Verify.Tests/DateFormatterTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -194,6 +194,55 @@ await Verify(new
});
}

[Fact]
public void SubMillisecondTicksDoNotCollide()
{
var date = new DateTime(2000, 10, 1, 0, 0, 0, DateTimeKind.Utc);
Assert.NotEqual(
DateFormatter.ToParameterString(date.AddTicks(1)),
DateFormatter.ToParameterString(date.AddTicks(2)));

var offset = new DateTimeOffset(2000, 10, 1, 0, 0, 0, TimeSpan.Zero);
Assert.NotEqual(
DateFormatter.ToParameterString(offset.AddTicks(1)),
DateFormatter.ToParameterString(offset.AddTicks(2)));
}

[Fact]
public Task SubMillisecondTicks()
{
var date = new DateTime(2000, 10, 1, 0, 0, 0, DateTimeKind.Utc);
var offset = new DateTimeOffset(2000, 10, 1, 0, 0, 0, TimeSpan.Zero);

var values = new Dictionary<string, object>();
foreach (var ticks in tickOffsets)
{
values.Add(
ticks.ToString(),
new
{
dateJson = DateFormatter.Convert(date.AddTicks(ticks)),
dateParameter = DateFormatter.ToParameterString(date.AddTicks(ticks)),
offsetJson = DateFormatter.Convert(offset.AddTicks(ticks)),
offsetParameter = DateFormatter.ToParameterString(offset.AddTicks(ticks))
});
}

return Verify(values);
}

static long[] tickOffsets =
[
0,
1,
2,
TimeSpan.TicksPerMillisecond,
TimeSpan.TicksPerSecond,
TimeSpan.TicksPerSecond + 1,
TimeSpan.TicksPerMinute,
TimeSpan.TicksPerMinute + 1
];

static bool[] bools =
[
true,
Expand Down
17 changes: 11 additions & 6 deletions src/Verify/Serialization/DateFormatter_DateTime.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,17 +16,20 @@ public static string Convert(DateTime value)

static string GetJsonDatePart(DateTime value)
{
if (value.TimeOfDay == TimeSpan.Zero)
// ticks, not the Second/Millisecond properties, since sub-millisecond ticks leave both of those zero
var ticks = value.TimeOfDay.Ticks;

if (ticks == 0)
{
return value.ToString("yyyy-MM-dd", Culture.InvariantCulture);
}

if (value is {Second: 0, Millisecond: 0})
if (ticks % TimeSpan.TicksPerMinute == 0)
{
return value.ToString("yyyy-MM-dd HH:mm", Culture.InvariantCulture);
}

if (value.Millisecond == 0)
if (ticks % TimeSpan.TicksPerSecond == 0)
{
return value.ToString("yyyy-MM-dd HH:mm:ss", Culture.InvariantCulture);
}
Expand All @@ -48,17 +51,19 @@ public static string ToParameterString(DateTime value)

static string GetParameterDatePart(DateTime value)
{
if (value.TimeOfDay == TimeSpan.Zero)
var ticks = value.TimeOfDay.Ticks;

if (ticks == 0)
{
return value.ToString("yyyy-MM-dd", Culture.InvariantCulture);
}

if (value is {Second: 0, Millisecond: 0})
if (ticks % TimeSpan.TicksPerMinute == 0)
{
return value.ToString("yyyy-MM-ddTHH-mm", Culture.InvariantCulture);
}

if (value.Millisecond == 0)
if (ticks % TimeSpan.TicksPerSecond == 0)
{
return value.ToString("yyyy-MM-ddTHH-mm-ss", Culture.InvariantCulture);
}
Expand Down
17 changes: 11 additions & 6 deletions src/Verify/Serialization/DateFormatter_DateTimeOffset.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,17 +11,20 @@ public static string Convert(DateTimeOffset value)

static string GetJsonDatePart(DateTimeOffset value)
{
if (value.TimeOfDay == TimeSpan.Zero)
// ticks, not the Second/Millisecond properties, since sub-millisecond ticks leave both of those zero
var ticks = value.TimeOfDay.Ticks;

if (ticks == 0)
{
return value.ToString("yyyy-MM-dd", Culture.InvariantCulture);
}

if (value is {Second: 0, Millisecond: 0})
if (ticks % TimeSpan.TicksPerMinute == 0)
{
return value.ToString("yyyy-MM-dd HH:mm", Culture.InvariantCulture);
}

if (value.Millisecond == 0)
if (ticks % TimeSpan.TicksPerSecond == 0)
{
return value.ToString("yyyy-MM-dd HH:mm:ss", Culture.InvariantCulture);
}
Expand All @@ -39,17 +42,19 @@ public static string ToParameterString(DateTimeOffset value)

static string GetParameterDatePart(DateTimeOffset value)
{
if (value.TimeOfDay == TimeSpan.Zero)
var ticks = value.TimeOfDay.Ticks;

if (ticks == 0)
{
return value.ToString("yyyy-MM-dd", Culture.InvariantCulture);
}

if (value is {Second: 0, Millisecond: 0})
if (ticks % TimeSpan.TicksPerMinute == 0)
{
return value.ToString("yyyy-MM-ddTHH-mm", Culture.InvariantCulture);
}

if (value.Millisecond == 0)
if (ticks % TimeSpan.TicksPerSecond == 0)
{
return value.ToString("yyyy-MM-ddTHH-mm-ss", Culture.InvariantCulture);
}
Expand Down
2 changes: 1 addition & 1 deletion src/todo.md
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Expand Up @@ -32,7 +32,7 @@ All six resolved 2026-08-16 (five fixed here; the inline item resolved as by-des
- [ ] **Negative UTC offsets formatted with current culture.**
`Verify/Serialization/DateFormatter_DateTimeOffset.cs:78,81` — plain interpolation (`$"{offset.Hours:0}"`) uses `CurrentCulture` while every other call in the file passes `Culture.InvariantCulture`. Under `ar-SA` the negative sign renders as invisible U+061C + `-`, so a `DateTimeOffset` parameter with offset `-05:00` produces a filename that never matches a snapshot committed from an en-US machine. Also leaks into snapshot content via `Convert` when date scrubbing is off.

- [ ] **Sub-millisecond date parameters collide.**
- [x] **Sub-millisecond date parameters collide.**
`Verify/Serialization/DateFormatter_DateTime.cs` (and the `DateTimeOffset` twin) use `Second == 0` / `Millisecond == 0` to omit the fraction, but sub-millisecond ticks leave those properties 0. `AddTicks(1)` and `AddTicks(2)` cases format identically → spurious "prefix has already been used" (or silent sharing of one verified file). Correct check is ticks-based.

- [ ] **`#` in parameter values collides with the indexed-target namespace.**
Expand Down
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