Add optional parameter to configuration providers for non-blocking startup

[GeorgeTsiokos]

Summary

Resolves #1748

• Adds an optional parameter to AddDaprConfigurationStore, AddStreamingDaprConfigurationStore, and AddDaprSecretStore extension methods so applications can start without blocking on Dapr sidecar availability
• Hardens LoadInBackgroundAsync in both providers with narrowed exception handling (OperationCanceledException + DaprException) instead of a broad catch (Exception) that silently swallowed programming errors
• Fixes resource leak by disposing CancellationTokenSource in both providers
• Fixes StringComparer inconsistency (InvariantCultureIgnoreCase → OrdinalIgnoreCase) in FetchSecretsAsync
• Makes fields readonly in DaprConfigurationStoreProvider for consistency with DaprSecretStoreConfigurationProvider
• Restores UTF-8 BOM per .editorconfig and adds missing trailing newlines

Test plan

• All 52 existing + new unit tests pass across net8.0, net9.0, net10.0
• New unit tests use GetReloadToken() callbacks for deterministic assertions (no fragile Task.Delay polling)
• Integration test: optional: true with delayed sidecar — config populates once sidecar starts (ShouldPopulateSecretsWhenSidecarStartsLate)
• Integration test: optional: false (default) behavior unchanged — Build() blocks until sidecar ready (ShouldBlockAndPopulateSecretsWhenNotOptional)
• Integration test: disposal during background loading exits cleanly without hanging (ShouldExitCleanlyWhenDisposedDuringBackgroundLoad)
• Integration tests updated to xUnit v3 (TestContext.Current.CancellationToken pattern)

🤖 Generated with Claude Code

[WhitWaldo]

Do note that I just merged a PR to support xUnit v3 so your unit/integration tests may need a refresh.

[GeorgeTsiokos]

A few items I'm intentionally leaving as-is — noting them here for visibility:

Pre-existing catch (Exception) in streaming subscription loop (DaprConfigurationStoreProvider.cs) — The broad catch in the SubscribeConfiguration retry loop predates this PR. It's there to reconnect on any stream error (including grpc status errors that aren't DaprException). Left unchanged to avoid scope creep.

UnsubscribeConfiguration throwing inside catch block — Same pre-existing code, same reasoning.

Exponential backoff — The flat sidecarWaitTimeout delay between retries is intentional. The sidecar typically becomes available within its startup window; exponential backoff would add unnecessary complexity for this use case.

Splitting the try block in LoadInBackgroundAsync — The current structure is deliberately compact to keep the retry logic readable. Happy to revisit if the reviewer feels strongly.

Non-optional blocking-failure test for config store — Pre-existing gap (the non-optional path throws on WaitForSidecar timeout, but there's no unit test for it). Out of scope for this PR.

IsOptional source/builder layer test — The existing end-to-end integration tests in SecretStoreOptionalTests.cs cover this path. A pure unit test for the source layer would be redundant.

[Copilot]

Pull request overview

This PR adds an optional parameter to Dapr configuration/secret store configuration providers so apps can start without blocking on sidecar availability, and expands test coverage (unit + integration) for the new behavior.

Changes:

• Add optional/IsOptional plumbing across configuration sources, providers, and extension methods for configuration store, streaming configuration store, and secret store.
• Introduce background loading logic and tighten exception handling/cancellation disposal behavior in providers.
• Add new unit/integration tests (and a new integration test project + testcontainers harness) validating late sidecar startup and clean disposal.

Reviewed changes

Copilot reviewed 12 out of 13 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
src/Dapr.Extensions.Configuration/DaprConfigurationStoreExtension.cs	Adds optional parameter to configuration store extension methods and passes it into the source.
src/Dapr.Extensions.Configuration/DaprConfigurationStoreSource.cs	Adds IsOptional to the source and forwards it to the provider.
src/Dapr.Extensions.Configuration/DaprConfigurationStoreProvider.cs	Implements optional non-blocking startup via background loading; updates cancellation/disposal behavior.
src/Dapr.Extensions.Configuration/DaprSecretStoreConfigurationExtensions.cs	Adds optional parameter across secret-store extension overloads and sets IsOptional.
src/Dapr.Extensions.Configuration/DaprSecretStoreConfigurationSource.cs	Adds IsOptional and forwards it to the provider.
src/Dapr.Extensions.Configuration/DaprSecretStoreConfigurationProvider.cs	Implements optional non-blocking startup via background loading; adds IDisposable and refactors fetch logic.
test/Dapr.Extensions.Configuration.Test/DaprConfigurationStoreProviderTest.cs	Adds unit tests covering optional behavior for config store providers.
test/Dapr.Extensions.Configuration.Test/DaprSecretStoreConfigurationProviderTest.cs	Adds unit tests covering optional behavior for secret store provider.
test/Dapr.IntegrationTest.Configuration/Dapr.IntegrationTest.Configuration.csproj	New integration test project for configuration/secret optional behavior.
test/Dapr.IntegrationTest.Configuration/SecretStoreOptionalTests.cs	New integration tests validating optional startup, late sidecar, and disposal behavior.
src/Dapr.Testcontainers/Common/DaprHarnessBuilder.cs	Adds a builder method for the new secret store harness.
src/Dapr.Testcontainers/Harnesses/SecretStoreHarness.cs	New harness for local file-based secret store used by integration tests.
all.sln	Adds the new integration test project; also introduces x64/x86 solution configurations.

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[WhitWaldo]

Superseded by #1844