Add DNS and TLS tests

[currantw]

Summary

Add integration tests for DNS resolution and TLS IPv4/IPv6 connectivity in the C# client.

Issue Link

⚪ None

Features and Behaviour Changes

Add new DNS and TLS tests, and centralize common test data and constants.
See more details below.

Implementation

New Tests

DnsTests class: DNS resolution tests with and without TLS for both cluster and standalone:

• Non-TLS connection succeeds with valid hostname.
• Non-TLS connection fails with invalid hostname.
• TLS connection succeeds with hostname present in certificate SAN.
• TLS connection fails with hostname not in certificate SAN.

TlsTests enhancements: TLS connectivity tests with IPv4 and IPv6 addresses:

• TLS connection succeeds with IPv4 address (127.0.0.1).
• TLS connection succeeds with IPv6 address (::1).

ClusterClientTests and StandaloneClientTests enhancements: connectivity tests with IPv4 and IPv6 addresses (without TLS):

• Connection succeeds with IPv4 address (127.0.0.1).
• Connection succeeds with IPv6 address (::1).

DNS tests require hostname mappings and the environment variable VALKEY_GLIDE_DNS_TESTS_ENABLED to be set.

Test Infrastructure Improvements

TestUtils.Constants class: Centralized shared test constants to eliminate duplication across test files:

• HostnameTls - Hostname included in certificate SAN
• HostnameNoTls - Hostname not in certificate SAN
• Ipv4Address - IPv4 loopback address
• Ipv6Address - IPv6 loopback address

TestUtils.Data class: Centralized common test data to eliminate duplication across test files, with ClusterMode and IpAddresses.

Server class enhancements:

• Made Addresses property public for test access.
• Added CertificatePath and CertificateData properties (reduce dependence on ServerManager and hide the fact that all servers share the same certificates).

Test refactoring: Updated all PubSub and other integration tests to use centralized Data.ClusterMode instead of local definitions, improving consistency and maintainability.

Limitations

DNS tests require host file entries mapping valkey.glide.test.tls.com and valkey.glide.test.no_tls.com to 127.0.0.1 and ::1. These must be configured manually for local development (automatically configured in CI).

Testing

See New Tests above.

Related Issues

• Java implementation: #5419
• Rust implementation: #5436
• Go implementation: #5479

Checklist

• This Pull Request is related to one issue.
• Commit message has a detailed description of what changed and why.
• Tests are added or updated and all checks pass.
• CHANGELOG.md, README.md, DEVELOPER.md, and other documentation files are updated.
• Destination branch is correct - main or release
• Create merge commit if merging release branch into main, squash otherwise.

[Copilot]

Pull request overview

Adds new integration coverage for DNS resolution and TLS connectivity variants in the C# client, and refactors shared test utilities to reduce duplication.

Changes:

• Introduces DNS/host-based integration tests and expands TLS test coverage.
• Centralizes shared theory data (ClusterMode) and updates PubSub tests to consume it.
• Enhances test Server utility with public addresses and certificate accessors; renames client creation APIs to async-style.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
valkey-glide	Updates submodule pointer to bring in upstream changes needed by the new tests/utilities.
tests/Valkey.Glide.TestUtils/Server.cs	Exposes server addresses/certs for tests and renames client creation methods to *Async.
tests/Valkey.Glide.TestUtils/Data.cs	Adds shared ClusterMode theory data for reuse across test suites.
tests/Valkey.Glide.IntegrationTests/TlsTests.cs	Refactors TLS tests/fixture and adds new certificate handling pathways.
tests/Valkey.Glide.IntegrationTests/PubSubUtils.cs	Switches PubSub theory generation to shared Data.ClusterMode.
tests/Valkey.Glide.IntegrationTests/PubSubQueueTests.cs	Updates MemberData to shared cluster-mode data.
tests/Valkey.Glide.IntegrationTests/PubSubIntrospectionTests.cs	Updates MemberData and server client creation calls to async naming.
tests/Valkey.Glide.IntegrationTests/PubSubEdgeCases.cs	Updates MemberData to shared cluster-mode data.
tests/Valkey.Glide.IntegrationTests/PubSubCoexistenceTests.cs	Updates MemberData to shared cluster-mode data.
tests/Valkey.Glide.IntegrationTests/PubSubCallbackTests.cs	Updates MemberData to shared cluster-mode data.
tests/Valkey.Glide.IntegrationTests/PubSubBasicTests.cs	Updates MemberData to shared cluster-mode data.
tests/Valkey.Glide.IntegrationTests/ISubscriberCompatibilityTests.cs	Updates MemberData to shared cluster-mode data.
tests/Valkey.Glide.IntegrationTests/DnsTests.cs	Adds new host/DNS-oriented connectivity tests (cluster/standalone, TLS/non-TLS, IPv4/IPv6).

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[Copilot]

Pull request overview

Copilot reviewed 15 out of 15 changed files in this pull request and generated 5 comments.

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