[thomhurst]

Summary

Test display names no longer depend on the machine's culture. Numeric arguments are formatted with CultureInfo.InvariantCulture, so [Arguments(1.5, -2)] is displayed as Test(1.5, -2) everywhere. Before this change it was Test(1,5, -2) under sv-SE/de-DE, which reads as three arguments, and −2 (U+2212) under ICU cultures that use the Unicode minus sign.

Root cause

ArgumentFormatter.FormatDefault formatted primitives and decimal with object.ToString(), which uses the current culture. Every display-name path goes through it: TestContext.GetDisplayName, DisplayNameAttribute, DisplayNameSubstitutor ($arg/$param), TestDataFormatter, TestContextExtensions and the engine's DisplayNameBuilder. So the bug showed up the same way in source-generated and reflection modes.

Fix

In ArgumentFormatter, numeric values are now formatted with IFormattable.ToString(null, CultureInfo.InvariantCulture). That covers primitive IFormattables (all integer types, nint/nuint, float, double), plus decimal, BigInteger, and Half/Int128/UInt128 on .NET. This matches TestNameFormatter.FormatArgumentValue, which already formats numbers invariantly.

What stays the same:

• bool, char, enums, strings (including the . → · escaping) and custom types.
• Custom ArgumentDisplayFormatters still run first.
• Dots in numbers are not escaped to · (the issue raised this as an open question). Doing that would change en-US display names too, so it is left out of this PR.

Because there is a single shared formatter, source-gen and reflection display names stay identical.

Behaviour change / release note: display names change for users on decimal-comma or Unicode-minus cultures. Saved filters or test history keyed on those names will see the new invariant form. Names under en-US and invariant cultures are unchanged.

Tests

• tests/TUnit.UnitTests/ArgumentFormatterCultureTests.cs (new file, so it doesn't conflict with Make the test suite pass in every environment and run fully in CI #7129's ArgumentFormatterTests.cs). It runs under invariant, en-US, and sv-SE/de-DE with a forced decimal comma and U+2212 minus, and covers top-level args, tuple/collection elements, parameterType overloads, modern numeric types, custom formatter precedence, and the non-numeric types listed above. 8 of the 24 cases fail without the fix and all pass with it (net10.0 and net8.0). The full TUnit.UnitTests suite passes (net10.0).
• tests/TUnit.TestProject/Bugs/7126 + tests/TUnit.Engine.Tests/Bug7126CultureInvariantDisplayNameTests.cs: an end-to-end test across both modes. A module initializer applies the culture named in TUNIT_BUG_7126_CULTURE (a no-op when it is unset), and the engine test runs the project under en-US, sv-SE and de-DE and checks the TRX test name.
  • Before the fix, under sv-SE: NumericArguments(1,5, -2, 2,25, 3,75) in both source-gen and --reflection modes.
  • After the fix: NumericArguments(1.5, -2, 2.25, 3.75) in both modes under sv-SE, de-DE and en-US (run directly against TUnit.TestProject).
  • Engine.Tests reflection mode: 3/3 pass. AOT mode is skipped locally (CI only).
• TUnit.TestProject *DisplayName*, Bugs._2136 and ArgumentsWithClassDataSourceTests filters pass in both modes.
• No generator output or public API changes.

Note on #7129

#7129 (now on main) added FormatArguments_WithTuples_FormatsCorrectly, which expected $"(1, a), 42, (True, {3.14})", i.e. current-culture output. This branch merges main and changes that expectation to the literal "(1, a), 42, (True, 3.14)" (203cf4f).

Fixes #7126

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes

  • Numeric values in test display names now use consistent formatting across locales, including numbers within tuples, collections, and complex values. Custom argument formatters continue to take precedence.

• Documentation

  • Clarified that numeric test arguments use invariant-culture formatting, while other values may vary by locale.

[chatgpt-codex-connector]

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📒 Files selected for processing: 3

• src/TUnit.Core/Helpers/ArgumentFormatter.cs
• tests/TUnit.UnitTests/ArgumentFormatterCultureTests.cs
• tests/TUnit.UnitTests/ArgumentFormatterTests.cs

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📝 Walkthrough

Numeric arguments in test display names now use invariant formatting across cultures. Other values retain their existing formatting path. Unit and end-to-end tests verify the display names, and the culture documentation describes the behavior.

Changes: Culture-Invariant Display Names

Layer / File(s)	Summary
Numeric formatting and unit coverage src/TUnit.Core/Helpers/ArgumentFormatter.cs, tests/TUnit.UnitTests/ArgumentFormatterCultureTests.cs, tests/TUnit.UnitTests/ArgumentFormatterTests.cs, docs/docs/writing-tests/culture.md	ArgumentFormatter.FormatDefault formats recognized numeric values with invariant culture. Tests cover numeric types, collections, custom formatters, and nonnumeric values across cultures. Documentation describes invariant numeric display names and custom formatter support.
End-to-end culture regression tests/TUnit.TestProject/Bugs/7126/Bug7126CultureInvariantDisplayNameTests.cs, tests/TUnit.Engine.Tests/Bug7126CultureInvariantDisplayNameTests.cs	The test project sets the requested culture and checks the numeric display name. The engine test runs the case under three cultures and checks the expected display name.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Bug fix · Severity of issue fixed: Medium

Suggested reviewers: quattordici

Merge Risk: ⚪ Minimal · up to 203cf

The numeric display-name change has no identified merge-blocking issue; proceed with normal checks.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 10.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 20 functions across 5 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: numeric display-name arguments now use invariant culture formatting.
Linked Issues check		The changes meet the coding requirements in [#7126]. ArgumentFormatter formats recognized numeric values with CultureInfo.InvariantCulture, including nested and modern numeric types. Custom format…
Out of Scope Changes check		The changes stay within [#7126]. The formatter update, culture regression tests, tuple expectation update, and documentation change support culture-independent numeric display names. No unrelated publ…

Full details: Linked Issues check

Explanation

The changes meet the coding requirements in [#7126]. ArgumentFormatter formats recognized numeric values with CultureInfo.InvariantCulture, including nested and modern numeric types. Custom formatters retain precedence. Unit and end-to-end tests cover decimal-comma and Unicode-minus cultures in source-generated and reflection modes. Numeric dot escaping is optional in the issue and is not required.

Full details: Out of Scope Changes check

Explanation

The changes stay within [#7126]. The formatter update, culture regression tests, tuple expectation update, and documentation change support culture-independent numeric display names. No unrelated public API, generator, or product behavior changes are reported.

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[chatgpt-codex-connector]

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Reviewed commit: 81eb529017

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Inline comments:
Review comments at @docs/docs/writing-tests/culture.md:
- Line 85: Update the statement about test display names to limit culture
independence to default numeric argument formatting; do not imply that
formatting nonnumeric values, such as DateTime arguments, is
culture-independent.

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📒 Files selected for processing: 5

• docs/docs/writing-tests/culture.md
• src/TUnit.Core/Helpers/ArgumentFormatter.cs
• tests/TUnit.Engine.Tests/Bug7126CultureInvariantDisplayNameTests.cs
• tests/TUnit.TestProject/Bugs/7126/Bug7126CultureInvariantDisplayNameTests.cs
• tests/TUnit.UnitTests/ArgumentFormatterCultureTests.cs

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[github-actions]

Review

Small, well-targeted fix. Formatting numerics with IFormattable.ToString(null, CultureInfo.InvariantCulture) in the single shared ArgumentFormatter.FormatDefault path keeps source-gen and reflection display names identical. It also matches TestNameFormatter.FormatArgumentValue.

What I checked:

• IsNumeric correctly excludes bool and char, which are primitive but not IFormattable. decimal, BigInteger and the #if NET types (Half, Int128, UInt128) are covered. nint/nuint are primitive IFormattables, so they are covered too.
• The call sits inside the existing try/catch, and custom ArgumentDisplayFormatters still run first.
• Tuples and collections recurse through the same path, and the unit tests cover them.
• The tests cover the formatter directly (including forced decimal-comma and U+2212 cultures, so they don't depend on ICU vs NLS) and end-to-end in both modes via the env-var culture. The release-note caveat is in the description, and the docs are updated.

Minor, non-blocking:

• Floating-point types under ToString(null, Invariant) use the same shortest round-trip format as before, so en-US names are unchanged. The Half/float cases are tested, which is enough.
• The [ModuleInitializer] in the TestProject only acts when the env var is set, so it can't affect other tests. A short comment saying so would help the next reader.

No blocking issues. LGTM.

[greptile-apps]

Confidence Score: 5/5

[Medium impact] The PR appears safe to merge; no blocking issues were found.

Summary

Numeric test arguments now use CultureInfo.InvariantCulture in display names.

• Numeric test arguments now keep the same display name across cultures.

No actionable issues were found. The full PR diff was reviewed because the previous and current commits have different merge bases with the target commit. No previous review threads were supplied.

_{Reviews (4) · Last reviewed commit: "test(core): guard the numeric type list ..." · Reviewed by Greptile}

[thomhurst]

Review dispositions (8805f9e):

• Codex (Complex/NFloat): fixed, thread resolved.
• CodeRabbit (docs claim too broad): fixed, thread resolved.
• claude-review nit (comment on the [ModuleInitializer]): added a comment explaining it is a no-op unless TUnit.Engine.Tests sets the env var.
• CodeRabbit docstring-coverage warning: not acted on; the touched members are private helpers and tests, consistent with the rest of the codebase.

[github-actions]

Review

The fix is correct and well scoped. I reviewed the diff only and did not build it or run the tests.

• Root cause: FormatDefault is the shared path for every display-name route. Fixing it there keeps source-gen and reflection modes identical.
• IsNumeric: the logic holds.
  • type.IsPrimitive && o is IFormattable excludes bool and char.
  • IntPtr/UIntPtr fall back to ToString() on runtimes where they aren't IFormattable.
  • Enums and custom types are untouched, and custom formatters still run first.
• Tests: coverage is good.
  • The unit tests pin the decimal comma and U+2212 minus explicitly, so they don't depend on ICU versus NLS behaviour.
  • The end-to-end test covers both modes under sv-SE and de-DE.
  • The module initializer only acts when the env var is set, so other tests in TUnit.TestProject are unaffected.

Minor suggestions, not blocking:

1. IsNumeric checks types one by one. If new numeric types appear, a plain o is IFormattable check would need an exclusion list (DateTime, TimeSpan, Guid, ...), so the explicit allow-list is the safer choice. A short comment saying so would help the next reader.
2. The PR description already calls out the display-name change for non-en-US users. Please make sure it goes into the release notes, because saved filters keyed on the old names will break.

LGTM.

[thomhurst]

Dispositions for the latest claude-review comment (on 8805f9e):

1. Comment on the IsNumeric allow-list: done in 80b9e2f. The comment says why the list is explicit (DateTime, DateTimeOffset, TimeSpan, Guid, enums and user types are also IFormattable and must keep their current text) and that a new numeric type has to be added there. Comment only, no behaviour change.
2. Release notes: no code change. The PR description already calls out that display names of numeric arguments change for non-en-US cultures. Making sure it lands in the release notes is for the owner at release time.

[github-actions]

Review

I read the diff but didn't build it or run the tests. I found no blocking issues, and this is a good fix.

What's good

• The fix is in one place. Every display-name path goes through ArgumentFormatter.FormatDefault, so source-gen and reflection modes stay identical.
• IsNumeric is an explicit allow-list. That keeps DateTime, Guid, TimeSpan, enums and user types unchanged, even though they are also IFormattable.
• Custom ArgumentDisplayFormatters still run first.
• The tests cover a lot:
  • the unit tests pin a decimal comma and U+2212 so they behave the same under NLS and ICU;
  • the end-to-end test runs under three cultures in both modes.
• The module initializer is a no-op unless the env var is set, so other tests in TUnit.TestProject aren't affected.
• The docs note and the release-note callout cover the behaviour change.

Suggestions (non-blocking)

1. The allow-list will go stale: a numeric type added to .NET later will silently use the current culture. Consider a unit test that reflects over System.Private.CoreLib types implementing INumberBase<T> (on .NET 7+). It would fail when a new numeric type isn't in the list, which is better than a code comment saying someone must remember.
2. type.IsPrimitive && o is IFormattable also covers IntPtr/UIntPtr. On netstandard2.0 they aren't IFormattable, so they fall through to ToString(), which is harmless. A short comment would stop someone else spending time checking it.
3. The Make the test suite pass in every environment and run fully in CI #7129 overlap is flagged in the description. Whichever PR merges second needs the 3.14 literal fix, so please make sure that happens.

Approving in spirit.

[thomhurst]

Review dispositions for 203cf4f.

github-actions review (comment 6279671850)

1. The numeric allow-list can go stale. Fixed in 203cf4f. Every_Runtime_Numeric_Type_Is_Formatted_Invariantly (net8.0+) finds every type in the runtime's numeric assemblies that implements INumberBase<T> for itself, creates -1.5 with T.CreateTruncating, and checks that ArgumentFormatter.Format gives the invariant text under a decimal-comma, U+2212 culture. I checked that it catches a gap: with Half removed from IsNumeric it fails with System.Half: '−1,5', expected '-1.5'. Types that cannot be created from a double are skipped, because their text has no culture-specific parts.
2. IntPtr/UIntPtr. Added the suggested comment to IsNumeric in 203cf4f. They are IFormattable from .NET 5, so they are formatted invariantly there. On netstandard2.0 they keep ToString(), which uses the invariant culture.
3. Make the test suite pass in every environment and run fully in CI #7129 overlap. Make the test suite pass in every environment and run fully in CI #7129 merged first, so this PR does the adjustment. 2aa5352 merges main, and 203cf4f changes FormatArguments_WithTuples_FormatsCorrectly to expect the literal "(1, a), 42, (True, 3.14)". The PR description is updated to match.

Local checks: ArgumentFormatter* tests pass on net8.0, net9.0 and net10.0 (38 each), and the full TUnit.UnitTests suite passes on net10.0 (604 passed, 4 skipped).

[github-actions]

Review of #7138

I reviewed the diff and the change looks correct and well scoped. I didn't build the project or run any tests. Nothing here blocks a merge.

What I checked

• The fix is one shared place, ArgumentFormatter.FormatDefault. Source-gen and reflection display names therefore stay identical, as AGENTS.md requires.
• Using an allow-list (IsNumeric) instead of a blanket o is IFormattable is the right call. DateTime, Guid, TimeSpan and enums are also IFormattable, and a blanket check would have silently changed their output.
• Custom ArgumentDisplayFormatters still run first.
• The unit tests are thorough. They cover decimal-comma and U+2212 cultures, tuples and collections, parameterType overloads, and modern numeric types.
• Every_Runtime_Numeric_Type_Is_Formatted_Invariantly checks every INumberBase<T> type in the runtime against the allow-list. That guards against the list going stale when a new .NET version adds a numeric type.
• The end-to-end test runs under sv-SE and de-DE in both modes, and the module-initializer culture hook does nothing when the env var is unset.
• The docs note and the behaviour-change note in the PR description are clear.

Minor suggestions (non-blocking)

• The generated Complex text differs between runtimes. That is acceptable, and the test already accounts for it.
• The ModuleInitializer in TUnit.TestProject runs for the whole module. The no-op guard makes this safe. If more culture-dependent tests are added later, a dedicated helper class would be easier to follow.
• The netstandard2.0 IntPtr behaviour relies on its ToString() being invariant. The code comment explains this, so no change is needed.

Approving from my side.

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