chore: abstract plain text settings into a SpannerOption

[sagnghos]

Introduce a SpannerOption usePlainText: a single, additive option that configures the channel for plaintext transport, disables credentials, and sets the protocol for plain-text communication when missing, making it easy and ergonomic to connect to experimental hosts over plain text communication.

[gemini-code-assist]

Summary of Changes

Hello @sagnghos, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a significant quality-of-life improvement for developers working with experimental Spanner hosts. By abstracting the complex setup for plaintext communication into a single usePlainText() option within SpannerOptions, it simplifies the process of configuring the client to connect to non-TLS endpoints. This change ensures that credentials are automatically disabled and the host URL is correctly formatted for plaintext, making it more ergonomic and secure for experimental use cases.

Highlights

• New usePlainText Option: Introduced a usePlainText() method in SpannerOptions.Builder to simplify configuring plaintext transport for experimental hosts.
• Automated Plaintext Configuration: This new option automatically sets the channel to use plaintext, disables credentials, and ensures the experimental host URL is prefixed with "http://" if it doesn't already specify a protocol.
• Refactored Experimental Host Setup: The ExperimentalHostHelper now leverages the new usePlainText() builder method, centralizing plaintext configuration logic and reducing redundancy.
• Improved Experimental Host Detection: The internal logic for detecting an experimental host was updated from a boolean flag (isExperimentalHost) to checking if the experimentalHost string is non-null, providing a more robust check.
• New Unit Tests: Added comprehensive unit tests to validate the correct behavior of the usePlainText option, covering various host input formats and different orders of builder method calls.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request introduces a new usePlainText option in SpannerOptions.Builder to simplify connecting to experimental hosts over plaintext. The implementation correctly handles setting up the channel for plaintext, disabling credentials, and ensuring the host string is correctly formatted with an http:// prefix regardless of the order of method calls. The changes are well-tested. I've added one suggestion to refactor some duplicated logic to improve code maintainability.

[rahul2393]

@sagnghos please help fix test

Error:    SpannerOptionsTest.testPlainTextOptions:1368 expected:<http://localhost:[808]0> but was:<http://localhost:[901]0>