Add test for non invariant default locale and collation

[steveharter]

No description provided.

[stephentoub]

@dotnet-bot test this please

[stephentoub]

@dotnet-bot test this please (after Jenkins changes related to setting culture-related env vars)

[steveharter]

@dotnet-bot test this please

[stephentoub]

@steveharter, given what we saw today with Jenkins and the various LANG/LC_*/etc. env vars, are there any additional tests we can/should add to validate behavior in such cases in the future?

[steveharter]

@stephentoub the other tests that were failing should probably be using Invariant culture explicitly and not assume en-us or other compatible culture for string formatting... For now, however, we could verify en-us in this test.

[steveharter]

FWIW, the default locale if no LANG is set is to use en-US-POSIX which has different default formatting settings than en-US or invariant.

[steveharter]

Four potential ways to address:

1. Do nothing
2. Change the tests that were failing to explicitly use Invariant
3. Add a test to verify en-US for Linux as the default locale
4. Change functionality to detect en-US-POSIX from Linux and then return the Invariant locale's culturedata or a copy of it (not sure if this is a valid approach)

[steveharter]

@ellismg do you have thoughts on the best way to address. I prefer option 2 (change tests to use invariant) and\or option 3 (verify en-us in unit test). Thanks

[steveharter]

FYI the list of tests that assume en-us or invariant (UPDATE: some of these tests fail due to unrelated case-insensitive string comparison failing for en-US-POSIX)
Int32Tests.TestTryParse
UInt32Tests.TestTryParse
UInt16Tests.TestTryParse
UInt64Tests.TestTryParse
StringTests.TestLastIndexOf
StringTests.TestEndsWith
StringTests.TestStartsWith
StringTests.TestIndexOf
Int16Tests.TestTryParse
Int64Tests.TestTryParse
TypeTests.TestGetTypeByName
Tests.Expression_Tests.TestCallInstanceMethodsByName
CaseInsensitiveComparer_ctor.ExecuteCaseInsensitiveComparer_ctor
CaseInsensitiveComparer_Default.ExecuteCaseInsensitiveComparer_Default
CaseInsensitiveComparer_Object.ExecuteCaseInsensitiveComparer_Object
CollectionsUtilTests.ExecuteCollectionsUtilTests
System.Reflection.Tests.ModuleTest.GetTypeTest
System.Reflection.Tests.MethodInfoPropertyTests.TestReturnType2
System.Reflection.Tests.MethodInfoPropertyTests.TestReturnType4
System.Reflection.Tests.GetTypeReflectionTests.GetType1
System.Reflection.Tests.ParameterInfoNameTests.TestMethodParams1

[ellismg]

I would prefer if these tests use Invariant.

[stephentoub]

Should we merge these test changes, and then address the non-invariant issue separately?

[steveharter]

Added issue #3850 to address the tests listed above. I will merge this pull request once I get the OK

[stephentoub]

This is pre-existing, but we should probably be resetting the current culture in a finally block. That way, if there's a bug that causes one of the asserts to fail, subsequent tests won't be thrown off by the change.

[stephentoub]

One pre-existing nit, otherwise LGTM.