Consolidate EC tests into S.S.C.

[PranavSenthilnathan]

Moves EC tests from System.Security.Cryptography.OpenSsl.Tests and System.Security.Cryptography.Cng.Tests to System.Security.Cryptography.Tests. Similar to #129320, the high-level strategy is:

• Create concrete ECDSA/ECDH factories (CNG, OpenSsl and default/ECDsa/ECDiffieHellman).
• Change static EC test classes to instance EC test class with virtualized ECDSA/ECDH factory accessors.
• Add a test registration class for each provider as a leaf of the instance-ified classes.
• XUnit conditional attributes can only reference static members, so instead move to throwing SkipTestException where needed.
• XUnit member data attributes can only reference static members, so, in the few places we need to, loop inside the test.

Contributes to #66338

[dotnet-policy-service]

Tagging subscribers to this area: @bartonjs, @vcsjones, @dotnet/area-system-security
See info in area-owners.md if you want to be subscribed.

[Copilot]

Pull request overview

This PR restructures elliptic-curve (ECDsa/ECDH) test coverage so provider-specific tests (CNG / OpenSSL / default) run under System.Security.Cryptography.Tests, using provider abstractions and “test registration” leaf classes to avoid per-assembly duplication and to work around xUnit’s static-only constraints.

Changes:

• Introduces provider abstractions (ECDsaProvider, ECDiffieHellmanProvider) plus concrete singleton providers for Default/Cng/OpenSsl, and refactors common EC tests to be instance-based with provider overrides.
• Adds per-provider “test registration” leaf classes in System.Security.Cryptography.Tests and removes EC test wiring from the OpenSsl/Cng test projects.
• Replaces xUnit conditional/static-member patterns with ConditionalFact/ConditionalTheory + SkipTestException runtime skipping (with new helpers).

Reviewed changes

Copilot reviewed 63 out of 64 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/libraries/System.Security.Cryptography/tests/X509Certificates/ExportTests.cs	Updates EC export tests to use new provider capability checks (one ECDH gating issue found).
src/libraries/System.Security.Cryptography/tests/TestData.Cng.cs	Adds CNG-specific key blobs and helpers into consolidated test project (Windows-only).
src/libraries/System.Security.Cryptography/tests/System.Security.Cryptography.Tests.csproj	Wires in new providers/registrations and links shared helpers for consolidated EC tests.
src/libraries/System.Security.Cryptography/tests/ECDsaTestRegistration.OpenSsl.cs	Adds OpenSSL ECDsa test leaf classes selecting the OpenSSL provider.
src/libraries/System.Security.Cryptography/tests/ECDsaTestRegistration.Default.cs	Adds default ECDsa test leaf classes selecting the default provider.
src/libraries/System.Security.Cryptography/tests/ECDsaTestRegistration.Cng.cs	Adds CNG ECDsa test leaf classes selecting the CNG provider.
src/libraries/System.Security.Cryptography/tests/EcDsaOpenSslTests.cs	Refactors OpenSSL-specific ECDsa tests to runtime skip checks + provider override.
src/libraries/System.Security.Cryptography/tests/EcDsaOpenSslProvider.cs	Renames/reshapes OpenSSL ECDsa provider implementation to derive from ECDsaProvider.
src/libraries/System.Security.Cryptography/tests/ECDsaCngTests.cs	Refactors CNG-specific ECDsa tests to use provider abstraction and runtime skip checks.
src/libraries/System.Security.Cryptography/tests/ECDsaCngProvider.cs	Renames/reshapes CNG ECDsa provider implementation to derive from ECDsaProvider.
src/libraries/System.Security.Cryptography/tests/ECDsaCngImportExportTests.cs	Refactors CNG-only import/export tests to use provider abstraction + runtime skip checks.
src/libraries/System.Security.Cryptography/tests/ECDiffieHellmanTestRegistration.OpenSsl.cs	Adds OpenSSL ECDH test leaf classes selecting the OpenSSL provider.
src/libraries/System.Security.Cryptography/tests/ECDiffieHellmanTestRegistration.Default.cs	Adds default ECDH test leaf classes selecting the default provider.
src/libraries/System.Security.Cryptography/tests/ECDiffieHellmanTestRegistration.Cng.cs	Adds CNG ECDH test leaf classes selecting the CNG provider.
src/libraries/System.Security.Cryptography/tests/EcDiffieHellmanOpenSslTests.cs	Refactors OpenSSL-specific ECDH tests to runtime skip checks and static execution.
src/libraries/System.Security.Cryptography/tests/EcDiffieHellmanOpenSslProvider.cs	Adds OpenSSL ECDH provider implementation for consolidated tests.
src/libraries/System.Security.Cryptography/tests/ECDiffieHellmanCngTests.cs	Extracts/renames CNG-specific ECDH test class away from shared partial base.
src/libraries/System.Security.Cryptography/tests/ECDiffieHellmanCngProvider.cs	Renames/reshapes CNG ECDH provider implementation to derive from ECDiffieHellmanProvider.
src/libraries/System.Security.Cryptography/tests/DefaultECDsaTests.cs	Renames/updates default ECDsa tests to use ECDsa.Create() directly.
src/libraries/System.Security.Cryptography/tests/DefaultECDsaProvider.Windows.cs	Refactors default ECDsa provider for Windows to derive from ECDsaProvider.
src/libraries/System.Security.Cryptography/tests/DefaultECDsaProvider.Unix.cs	Refactors default ECDsa provider for Unix to derive from ECDsaProvider.
src/libraries/System.Security.Cryptography/tests/DefaultECDsaProvider.cs	Refactors default ECDsa provider core implementation as a singleton ECDsaProvider.
src/libraries/System.Security.Cryptography/tests/DefaultECDsaProvider.Browser.cs	Refactors browser default ECDsa provider shim to match new abstraction.
src/libraries/System.Security.Cryptography/tests/DefaultECDsaProvider.Android.cs	Refactors Android default ECDsa provider shim to match new abstraction.
src/libraries/System.Security.Cryptography/tests/DefaultECDiffieHellmanTests.cs	Renames/updates default ECDH tests to use ECDiffieHellman.Create() directly.
src/libraries/System.Security.Cryptography/tests/DefaultECDiffieHellmanProvider.Windows.cs	Refactors default ECDH provider for Windows to derive from ECDiffieHellmanProvider.
src/libraries/System.Security.Cryptography/tests/DefaultECDiffieHellmanProvider.Unix.cs	Refactors default ECDH provider for Unix to derive from ECDiffieHellmanProvider.
src/libraries/System.Security.Cryptography/tests/DefaultECDiffieHellmanProvider.cs	Refactors default ECDH provider core implementation as a singleton ECDiffieHellmanProvider.
src/libraries/System.Security.Cryptography/tests/DefaultECDiffieHellmanProvider.Browser.cs	Refactors browser default ECDH provider shim to match new abstraction.
src/libraries/System.Security.Cryptography/tests/DefaultECDiffieHellmanProvider.Android.cs	Refactors Android default ECDH provider shim to match new abstraction.
src/libraries/System.Security.Cryptography.OpenSsl/tests/System.Security.Cryptography.OpenSsl.Tests.csproj	Removes EC test wiring now covered by consolidated test project.
src/libraries/System.Security.Cryptography.OpenSsl/tests/EcDiffieHellmanOpenSslProvider.cs	Deletes OpenSSL EC provider previously living in OpenSsl test project.
src/libraries/System.Security.Cryptography.Cng/tests/System.Security.Cryptography.Cng.Tests.csproj	Removes EC test wiring; links shared TestData.Cng.cs instead.
src/libraries/System.Security.Cryptography.Cng/tests/PropertyTests.cs	Removes now-unneeded EC test namespace usage due to consolidation.
src/libraries/System.Security.Cryptography.Cng/tests/OpenTests.cs	Removes now-unneeded EC test namespace usage due to consolidation.
src/libraries/Common/tests/System/Security/Cryptography/ExceptionHelpers.cs	Adds SkipTestException.ThrowUnless/ThrowWhen helpers to support runtime skipping.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDsa/ECDsaXml.cs	Makes shared ECDsa XML tests abstract/instance-based under new provider model.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDsa/ECDsaTestsBase.cs	Adds abstract provider accessor; converts capability probes to instance members.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDsa/ECDsaTests.NistValidation.cs	Converts helper methods to instance context for provider-based execution.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDsa/ECDsaTests.netcoreapp.cs	Switches some MemberData patterns to inline loops + runtime skipping.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDsa/ECDsaTests.cs	Makes shared ECDsa tests abstract and provider-driven; adjusts data generation patterns.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDsa/ECDsaStub.cs	Deletes obsolete stub type now that tests instantiate via provider.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDsa/ECDsaSignatureFormatTests.cs	Caches generated keys per provider instance; converts to provider-driven generation.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDsa/ECDsaProvider.cs	Adds new provider abstraction for ECDsa.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDsa/ECDsaKeyFileTests.cs	Makes key-file tests abstract and provider-capability-driven.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDsa/ECDsaImportExport.cs	Refactors import/export tests to runtime skip checks + provider execution.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDsa/ECDsaFactoryTests.cs	Converts factory tests to abstract/provider-driven instance tests.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDsa/ECDsaFactory.cs	Deletes old static factory indirection replaced by provider abstraction.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDiffieHellman/ECDiffieHellmanTests.Xml.cs	Converts XML tests to instance-based execution under provider model.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDiffieHellman/ECDiffieHellmanTests.Tls.cs	Replaces MemberData usage with per-keysize loops; keeps behavior via helpers.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDiffieHellman/ECDiffieHellmanTests.Raw.cs	Converts raw-derivation tests to runtime skip checks + loop helpers.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDiffieHellman/ECDiffieHellmanTests.NistValidation.cs	Converts NIST validation helpers to instance context for provider-based execution.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDiffieHellman/ECDiffieHellmanTests.ImportExport.cs	Refactors import/export tests to runtime skip checks + provider execution.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDiffieHellman/ECDiffieHellmanTests.Hmac.cs	Converts HMAC derivation tests to loop-based execution + runtime skip checks.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDiffieHellman/ECDiffieHellmanTests.Hash.cs	Converts hash derivation tests to loop-based execution + runtime skip checks.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDiffieHellman/ECDiffieHellmanTests.cs	Makes shared ECDH tests abstract/provider-driven; adds per-provider keysize caches + loop helpers.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDiffieHellman/ECDiffieHellmanProvider.cs	Adds new provider abstraction for ECDiffieHellman.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDiffieHellman/ECDiffieHellmanKeyPemTests.cs	Fixes namespace/abstraction and routes key creation through provider.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDiffieHellman/ECDiffieHellmanFactoryTests.cs	Converts factory tests to abstract/provider-driven instance tests.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDiffieHellman/ECDiffieHellmanFactory.cs	Deletes old static factory indirection replaced by provider abstraction.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/ECDiffieHellman/ECDhKeyFileTests.cs	Makes key-file tests abstract and provider-capability-driven.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/EC/ECKeyFileTests.cs	Virtualizes per-algorithm capabilities (explicit curves / public-key derivation / curve support).
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/EC/EccTestBase.cs	Reworks curve data sets for runtime validation rather than static filtering.
src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/EC/CurveDef.cs	Moves curve validity checks to provider-specific methods.