Add dotnet test --list-tests json via SDK-side rendering

[Evangelink]

Fixes #49754.

Approach

This implements dotnet test --list-tests json by having the SDK render the JSON itself from the discovered-test data it already receives over the dotnettestcli IPC protocol — rather than forwarding the flag to the test host.

This supersedes #54490 (now closed). That PR forwarded --list-tests json to MTP's TerminalOutputDevice, which early-returns when _isServerMode is true — and the SDK always sets --server dotnettestcli. So the host never emits JSON through dotnet test, and it would have required a separate testfx fix plus risked stdout interleaving.

The key realization: the MTP IPC wire contract (vendored from microsoft/testfx, already on main via cd590b6b4b) already carries the full discovered-test payload — Uid, DisplayName, FilePath, LineNumber, Namespace, TypeName, MethodName, ParameterTypeFullNames, Traits. In --list-tests mode the SDK handshakes as Discover and receives these messages today; it was simply dropping 5 of the 9 fields before rendering text. So no testfx change and no protocol break are needed — just SDK-side plumbing and rendering.

JSON shape

A versioned envelope grouped by test container (assembly + TFM + architecture), preserving every field the wire contract provides:

{
  "version": "1.0",
  "testContainers": [
    {
      "assemblyPath": "...\\TestProject.dll",
      "targetFramework": "net11.0",
      "architecture": "x64",
      "tests": [
        {
          "uid": "...",
          "displayName": "...",
          "namespace": "My.Ns",
          "typeName": "MyClass",
          "methodName": "MyMethod",
          "parameterTypeFullNames": ["System.Int32"],
          "traits": [ { "key": "Category", "value": "Fast" } ],
          "filePath": "...",
          "lineNumber": 42
        }
      ]
    }
  ]
}

Grouping by container (not by class) preserves the module/TFM dimension a multi-project dotnet test spans, keeps each entry truthful to the underlying test node (unique Uid), and lets consumers group by namespace+typeName themselves. The envelope is versioned so the shape can evolve.

Changes

• CLI definition: --list-tests arity Zero → ZeroOrOne, restricted to text/json via AcceptOnlyFromAmong, HelpName = text|json. Updated CmdListTestsDescription and regenerated all .xlf files (/t:UpdateXlf).
• TestListFormat enum + TestOptions.ListTestsFormat; read from the option value (bare --list-tests still defaults to text).
• MicrosoftTestingPlatformTestCommand: for json, force NoAnsi + no progress + no assembly banners so stdout contains only the JSON document.
• TestApplicationHandler.OnDiscoveredTestsReceived: forward all 9 fields (was dropping namespace/typeName/methodName/parameterTypeFullNames/traits).
• TestProgressState: DiscoveredTestNames now holds a DiscoveredTestInfo record with all fields.
• TerminalTestReporter: renders the JSON via Utf8JsonWriter (trim/AOT-safe, no reflection); text discovery output is unchanged.
• The bare --list-tests token is still forwarded to the host unchanged — the format selection stays SDK-local.

Testing

• New unit test asserting the JSON shape (TerminalTestReporterTests).
• New CLI parser tests (text/json accepted, bare --list-tests = null/text, invalid values rejected).
• New end-to-end discovery integration test (--list-tests json).
• Updated TestProgressStateTests / TestApplicationHandlerTests for the widened signatures, and the MTP help snapshot.
• Verified end-to-end against the built redist SDK: stdout is exactly the JSON document + newline, nothing else.

For frameworks that don't set TestMethodIdentifierProperty, the rich fields are simply null/empty (each test still carries its uid/displayName).

[azure-pipelines]

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[Copilot]

Pull request overview

Adds support for dotnet test --list-tests json for the Microsoft.Testing.Platform-based dotnet test flow by rendering JSON in the SDK from the discovered-test payload already received over the existing dotnettestcli IPC protocol (no protocol changes required).

Changes:

• Extends --list-tests to optionally accept text|json, and plumbs the selected format through TestOptions.
• Preserves the full discovered-test payload (namespace/type/method/params/traits/location) and renders a versioned, container-grouped JSON document via Utf8JsonWriter.
• Adds/updates unit, parser, snapshot, and end-to-end tests; updates localized strings for the revised help text.

Show a summary per file

File	Description
test/dotnet.Tests/CommandTests/Test/TestProgressStateTests.cs	Updates discovery-state tests for DiscoveredTestInfo (including Uid rename).
test/dotnet.Tests/CommandTests/Test/TestCommandParserTests.cs	Adds parser tests for --list-tests accepting `text
test/dotnet.Tests/CommandTests/Test/TestApplicationHandlerTests.cs	Updates TestOptions construction to include ListTestsFormat.
test/dotnet.Tests/CommandTests/Test/TerminalTestReporterTests.cs	Adds unit test asserting the JSON envelope/container/test shape.
test/dotnet.Tests/CommandTests/Test/snapshots/MTPHelpSnapshotTests.VerifyMTPHelpOutput.verified.txt	Updates help snapshot for `--list-tests <text
test/dotnet.Tests/CommandTests/Test/GivenDotnetTestBuildsAndDiscoversTests.cs	Adds end-to-end test validating JSON discovery output shape/content.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.zh-Hant.xlf	Updates localized resource entry for revised --list-tests description.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.zh-Hans.xlf	Updates localized resource entry for revised --list-tests description.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.tr.xlf	Updates localized resource entry for revised --list-tests description.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.ru.xlf	Updates localized resource entry for revised --list-tests description.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.pt-BR.xlf	Updates localized resource entry for revised --list-tests description.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.pl.xlf	Updates localized resource entry for revised --list-tests description.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.ko.xlf	Updates localized resource entry for revised --list-tests description.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.ja.xlf	Updates localized resource entry for revised --list-tests description.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.it.xlf	Updates localized resource entry for revised --list-tests description.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.fr.xlf	Updates localized resource entry for revised --list-tests description.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.es.xlf	Updates localized resource entry for revised --list-tests description.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.de.xlf	Updates localized resource entry for revised --list-tests description.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.cs.xlf	Updates localized resource entry for revised --list-tests description.
src/Cli/Microsoft.DotNet.Cli.Definitions/Commands/Test/TestCommandDefinition.MicrosoftTestingPlatform.cs	Changes --list-tests arity to ZeroOrOne, constrains values to `text
src/Cli/Microsoft.DotNet.Cli.Definitions/CommandDefinitionStrings.resx	Updates CmdListTestsDescription to document optional `text
src/Cli/dotnet/Commands/Test/MTP/TestApplicationHandler.cs	Forwards the full discovered-test payload into DiscoveredTestInfo.
src/Cli/dotnet/Commands/Test/MTP/Terminal/TestProgressState.cs	Stores rich discovery nodes via DiscoveredTestInfo instead of a reduced tuple.
src/Cli/dotnet/Commands/Test/MTP/Terminal/TerminalTestReporterOptions.cs	Adds ListTestsFormat option to control discovery rendering.
src/Cli/dotnet/Commands/Test/MTP/Terminal/TerminalTestReporter.cs	Adds JSON discovery rendering and routes discovery summary based on ListTestsFormat.
src/Cli/dotnet/Commands/Test/MTP/Options.cs	Introduces TestListFormat and extends TestOptions with ListTestsFormat.
src/Cli/dotnet/Commands/Test/MTP/MicrosoftTestingPlatformTestCommand.cs	Derives list-tests format from parse result and suppresses non-JSON terminal features during JSON discovery.

Copilot's findings

• Files reviewed: 27/27 changed files
• Comments generated: 0

[Evangelink]

CI triage: the 3 red legs are pre-existing infra failures, unrelated to this change

I investigated the failing pipeline (build 1510506). All three failing legs reproduce identically on the latest main build (1509939), which this branch is already based on top of:

Failing leg	Root cause	Pre-existing?
Build AoT: windows (arm64)	LNK1322: cannot avoid potential ARM hazard (Cortex-A53 MPCore processor bug #843419) during the NativeAOT win-x64 → win-arm64 cross-link of dotnet-aot.exe. A toolchain/linker (ILC / MSVC arm64 linker) failure, no managed code involved.	Yes — tracked by #55298 (cc @dotnet/illink), same failure & duration on main.
Build TestBuild: linux (x64)	Run NativeAOT CLI Tests → "Zero tests ran" (exit code 8).	Yes — the NativeAOT CLI test runner added in #54719 has reported zero tests since it was introduced (green at 7ee70d13 → red starting at 1c430679 which added it). Same failure on main.
Build TestBuild: windows (x64)	Same "Zero tests ran" as above.	Yes — same as above.

None of these touch the dotnet test --list-tests json code paths in this PR. This change is validated locally: 113 targeted tests pass (JSON unit test, CLI parser tests, discovery integration test, updated help snapshot), and a real end-to-end dotnet test --list-tests json run against the built redist SDK emits exactly the JSON document on stdout.

These infra legs are owned by the NativeAOT CI work (#55298 and the #54719 runner) and are out of scope for this feature PR.