System.Drawing.Tests.FontFamilyTests.Families_Get_ReturnsExpected failure on libgdiplus platforms

[directhex]

Mono and CoreCLR both fail near-identically on this test on Helix.

CoreCLR https://helix.dot.net/api/2019-06-17/jobs/4f122c80-6e43-48c3-9793-d5c72dc59bbd/workitems/System.Drawing.Common.Tests/console

    System.Drawing.Tests.FontFamilyTests.Families_Get_ReturnsExpected [FAIL]
      Assert.Equal() Failure
                ↓ (pos 0)
      Expected: Noto Sans Inscriptional Parthia
      Actual:   Verdana
                ↑ (pos 0)
      Stack Trace:
        /_/src/libraries/System.Drawing.Common/tests/FontFamilyTests.cs(126,0): at System.Drawing.Tests.FontFamilyTests.Families_Get_ReturnsExpected()

Mono https://helix.dot.net/api/2019-06-17/jobs/6648e68b-974b-4787-9345-e0223c696d09/workitems/System.Drawing.Common.Tests/console

    System.Drawing.Tests.FontFamilyTests.Families_Get_ReturnsExpected [FAIL]
      Assert.Equal() Failure
                ↓ (pos 0)
      Expected: Noto Sans Inscriptional Parthia
      Actual:   Verdana
                ↑ (pos 0)
      Stack Trace:
        /_/src/libraries/System.Drawing.Common/tests/FontFamilyTests.cs(126,0): at System.Drawing.Tests.FontFamilyTests.Families_Get_ReturnsExpected()
        /_/src/mono/netcore/System.Private.CoreLib/src/System/Reflection/RuntimeMethodInfo.cs(384,0): at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)

We get the same failure on macOS 10.15, and the text implies an issue with the base VM configuration (missing fonts? Too many fonts? Fonts returned in the wrong order?)

Tagging subscribers to this area: @safern, @tannergooding
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[directhex]

I think this is actually a real issue

The test is enumerating every font on the system, creating a new font object from each entry's name, and verifying that they match (i.e. checking "i got a font with name X, and can create a font with the same name"). It appears to be failing on fonts with long names, defaulting to Verdana:

family Droid Sans Mono Slashed for Pow
copy   Verdana
family Droid Sans Mono Dotted for Powe
copy   Verdana
family Roboto Mono Medium for Powerlin
copy   Verdana
family Ubuntu Mono derivative Powerlin
copy   Verdana
family Noto Sans Inscriptional Parthia
copy   Verdana

I need to see if this is behaviour changed in 10.15, or there were no long-named fonts, or what

[directhex]

Yeah, real bug.

Catalina font list

High Sierra font list

The bug wasn't previously discovered, because HS does not ship with any fonts whose name exceeds LF_FACESIZE from wingdi.h (32 chars)

Related, with possible thoughts on workarounds we'll need to implement in libgdiplus: microsoft/terminal#602

[directhex]

Confirmed this issue happens on Linux with big font names.

It does NOT happen on Windows, which truncates the font name differently and successfully does new FontFamily(fontFamily.Name) with the truncated name.