Fixes issues with --delete-data=on-conflict

[cloutiertyler]

Description of Changes

Fixes #3729

I genuinely don't know what came over me.

API and ABI breaking changes

None

Expected complexity level and risk

1.5 very straightforward but not strictly trivial

Testing

Adds automated integration tests (written in Rust and run with cargo test, although note this comment from @matklad about integration tests for the future https://internals.rust-lang.org/t/running-test-crates-in-parallel/15639/2):

• Can publish an updated module if no migration is required
• Can publish an updated module if auto-migration is required (with the yes-break flag true/false)
• Cannot publish if a manual migration is required
• Can publish if a manual migration is required but the user specified --delete-data
• Can publish if a manual migration is required by the user specified --delete-data=on-conflict
• No data deletion occurs if no migration is required and --delete-data=on-conflict is specified

[bfops]

From a black box perspective, I would like you to test the following cases, with each value of --delete-data:

• no migration required
• auto-migrateable (with the yes-break flag true/false)
• manual migration required

Edit: I would like to consider making these into automated tests!

Given the original issue, please also spot-test spacetime dev.

[jdetter]

Shall we do a hotfix release with this?

[Copilot]

Pull request overview

This PR fixes issues with the --delete-data=on-conflict flag in the SpacetimeDB CLI's publish command. The main problem was that the data deletion prompt and logic were being executed at the wrong time in the publish flow, and the flag wasn't being properly respected when auto-migration was possible.

Key changes:

• Fixed the logic for --delete-data=on-conflict to only delete data when a manual migration is required, not when auto-migration is available
• Moved data deletion prompts and logic into the apply_pre_publish_if_needed function where migration decisions are made
• Added support for --features flag to enable building Rust modules with different feature sets for testing
• Added comprehensive integration tests to verify all migration scenarios

Reviewed changes

Copilot reviewed 15 out of 16 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
crates/cli/src/subcommands/publish.rs	Refactored data deletion logic to occur within migration decision flow, fixed handling of --delete-data=on-conflict
crates/cli/src/subcommands/build.rs	Added --features flag support for Rust builds
crates/cli/src/tasks/rust.rs	Updated build function to accept and pass features to cargo
crates/cli/src/tasks/mod.rs	Added features parameter and validation for non-Rust modules
crates/cli/tests/publish.rs	Added comprehensive integration tests for all publish/migration scenarios
crates/cli/tests/util.rs	Added utility for spawning SpacetimeDB instances in tests
crates/cli/tests/server.rs	Added basic server connectivity test
modules/module-test/src/lib.rs	Added conditional compilation features for testing migrations
modules/module-test/Cargo.toml	Added feature flags for migration testing
crates/testing/src/modules.rs	Updated to pass new features parameter
crates/cli/src/subcommands/dev.rs	Updated to use new build API with features parameter
crates/codegen/tests/snapshots/*.snap	Updated snapshots to include generated code for new test table

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[jdetter]

Just one question but no objections from me on this, thanks for cleaning this one up Zeke 🙏

I have not tested this myself but this was in last week's release and we haven't seen any complaints about this issue since the last release.