On my machine this test was always failing because for some reason a NNBSP char instead of a whitespace is added:

I think we should find the reason instead of this workaround.

Yeah, it would be nice to find the root cause of this problem.
If you open DataGridPropertyColumnNullCheckTest in the viewer, does it also render  ?
What I don’t understand is why it only appears between the time and the AM|PM?

1/1/0001 12:00:00\u202FAM

It seems like there’s none between the date and the time, and the "some text" is not affected either. So, it doesn’t seem like #9916 is the cause.

What happens if you remove or replace SetCulture? We use it in other places too, though we don't deal with datetime there.

I had a hunch this might be related to ICU... A quick google search confirmed it:

microsoft/icu#134

Just to say I am on mac and get the same error

@ScarletKuro I tried your suggestion of setting culture to Invariant and it gives

       [Test]
        [SetCulture("")]
        [SetUICulture("")]
        public void DataGridPropertyNullCheck()
        {
            var comp = Context.RenderComponent<DataGridPropertyColumnNullCheckTest>();
            var cells = comp.FindAll("td").ToArray();

            // First Row
            cells[0].TextContent.Should().Be("1/1/0001 12:00:00 AM");

Expected cells[0].TextContent to be "1/1/0001 12:00:00 AM" with a length of 20, but "01/01/0001 00:00:00" has a length of 19, differs near "01/" (index 0).

Quality Gate passed

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.52%. Comparing base (f028a0f) to head (34f3b22).
Report is 23 commits behind head on dev.

@@            Coverage Diff             @@
##              dev   #10220      +/-   ##
==========================================
+ Coverage   91.22%   91.52%   +0.30%     
==========================================
  Files         412      414       +2     
  Lines       12541    12989     +448     
  Branches     2448     2452       +4     
==========================================
+ Hits        11440    11888     +448     
+ Misses        557      555       -2     
- Partials      544      546       +2     

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@ScarletKuro works locally for me now, Ready to merge.

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