fix: standardize assertion error message formatting

[thomhurst]

Summary

Fixes #4867

• GetExpectation() now consistently uses the "to [verb] [value]" pattern across all assertion conditions (e.g., "to match regex" instead of "text match regex", "to not match pattern" instead of "text to not match with pattern")
• Failure messages now consistently use "received [actual]" instead of a mix of "found", "value is", "was", "both values are", etc.
• Exception type names in throw assertions now consistently use .Name (short name like OtherException) instead of .FullName (fully qualified like TUnit.Assertions.Tests.Assertions.Delegates.Throws+OtherException)

Files changed

17 source files in TUnit.Assertions/Conditions/ and TUnit.Assertions/Collections/:

• StringAssertions.cs - regex/pattern match expectation wording, failure message standardization
• StringEqualsAssertion.cs - "found" to "received" in diff messages
• EqualsAssertion.cs, EquatableAssertion.cs - .FullName to .Name, "found" to "received"
• NotEqualsAssertion.cs - "both values are" to "received"
• NullAssertion.cs - "value is null/default" to "received null/default"
• GreaterThanAssertion.cs, LessThanAssertion.cs, BetweenAssertion.cs - "value is null" / "found" to "received"
• PredicateAssertions.cs - "value does not satisfy" to "received"
• ReferenceEqualityAssertions.cs - "references are different/same" to "received different/same references"
• TypeOfAssertion.cs - "type was" to "received type"
• AsyncEnumerableAssertions.cs - "was null" / "item X was not found" to "received null" / "X was not found in the collection"
• CollectionCountSource.cs, CollectionChecks.cs - "found" to "received", "it was empty" to "received empty collection"
• SetAssertions.cs - "to equal" to "to be equal to" in GetExpectation
• ThrowsAssertion.cs - .FullName to .Name

10 test files updated to match the new message format.

Test plan

• dotnet build TUnit.Assertions/TUnit.Assertions.csproj passes with 0 errors
• dotnet test TUnit.Assertions.Tests/TUnit.Assertions.Tests.csproj - all 6935 tests pass across net8.0, net9.0, net10.0, and net48
• CI pipeline passes

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

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This is a clean, well-executed consistency pass. A few things worth noting positively:

• Subject-first convention in DoesNotContain: The old found "{expected}" in "{value}" placed the expected value first; the new received "{value}" which contains "{expected}" correctly leads with the actual/received value. This matches the standard assertion reporting convention.
• .Name over .FullName for exceptions: For nested types like Throws+OtherException, the old .FullName would render as TUnit.Assertions.Tests.Assertions.Delegates.Throws+OtherException — cluttered and hard to read. .Name gives OtherException, which is unambiguous in context and much cleaner in test failure output.
• GetExpectation() grammar fixes: "text match regex" → "to match regex" corrects both the grammar and aligns with the "to [verb]" pattern used throughout the library.
• Test coverage: All 10 test files are properly updated to match the new message format, and the author reports all 6,935 tests passing across net8.0, net9.0, net10.0, and net48.

No CLAUDE.md rule violations, no bugs, no logic issues, no security concerns. The change is purely mechanical string replacements with consistent application across all affected files.