testbot: require go_test BUILD targets for new Go test files

[jiaenren]

Summary

PR #956 (testbot-generated) added src/runtime/pkg/common/common_test.go but didn't add a corresponding go_test rule to the package's BUILD file. The test file is invisible to Bazel:

$ bazel test //src/runtime/pkg/common:all
ERROR: No test targets were found, yet testing was requested
$ bazel query 'kind(go_test, //src/runtime/pkg/common/...)'
INFO: Empty results

Net effect: a testbot run that picked common.go because of "0% coverage" closed the gap with a PR that ships zero new measured coverage — bazel coverage //... won't run a test target it doesn't know about, and Codecov never sees the result.

This PR teaches the testbot to wire up Go tests properly going forward:

• TESTBOT_PROMPT.md step 6: generalized from "Python only" to cover Go. Includes the canonical pattern (go_library + go_test with embed = [":<pkg>"]) verified against src/runtime/pkg/data/BUILD, and a "check it worked" instruction — re-run bazel test and watch for No test targets were found.
• TESTBOT_RULES.md verification step: explicitly call out the "No test targets were found" failure mode and point at BUILD wiring. New "BUILD wiring (Python + Go)" subsection explains why a go_library-only BUILD silently drops adjacent _test.go files.
• TESTBOT_PROMPT.md guardrails: include go_test alongside py_test in the allowed BUILD edits.

Documentation-only change to the prompt files. No code paths or tests change.

Issue - None

Files tested

• N/A — this updates the agent's instructions, not source code.

Checklist

• I am familiar with the Contributing Guidelines
• New or existing tests cover these changes (14/14 testbot bazel tests still pass)
• The documentation is up to date with these changes (this is the documentation)

Test plan

• bazel test //src/scripts/testbot/tests/... (still green)
• Next testbot generate run picks a Go target and produces a PR with both _test.go AND a go_test BUILD entry, then bazel coverage //... actually shows non-zero coverage on the targeted file.

Follow-up

PR #956 itself still needs the go_test rule appended to src/runtime/pkg/common/BUILD to take effect. I'd suggest either pushing the fix to that branch directly or asking testbot to follow up via /testbot add a go_test rule to BUILD for common_test.go.

Summary by CodeRabbit

• Documentation
  • Expanded test-generation guidance with detailed BUILD file handling and Bazel wiring instructions for Python and Go, including verification steps and a Bazel-specific test failure path.
  • Clarified that test-generation changes are restricted to test files and BUILD entries (py_test/go_test), with no modifications to source code or configuration files.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: bd7581bc-fb43-421f-b9da-db1cd76dad62

📥 Commits

Reviewing files that changed from the base of the PR and between 2791843 and 19e6a07.

📒 Files selected for processing (1)

• src/scripts/testbot/TESTBOT_PROMPT.md

🚧 Files skipped from review as they are similar to previous changes (1)

• src/scripts/testbot/TESTBOT_PROMPT.md

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📝 Walkthrough

Walkthrough

This PR augments testbot documentation with cross-language Bazel BUILD wiring guidance for Python and Go tests, clarifies Bazel test failure handling, and tightens guardrails to permit edits only to test files and BUILD entries (no source/config changes).

Changes

Testbot BUILD wiring & Guardrails

Layer / File(s)	Summary
Test Failure Guidance src/scripts/testbot/TESTBOT_RULES.md (lines 56–59)	Adds Bazel-specific note under "Run the test": if bazel test reports no test targets, the test file may not be wired into the BUILD; points to BUILD wiring section.
BUILD File Guidance (data / examples) src/scripts/testbot/TESTBOT_PROMPT.md (lines 32–51)	Introduces cross-language BUILD guidance with example snippets for py_test() and go_test() wiring, showing load statements, go_library/go_test pattern, and embedding for coverage.
BUILD Wiring Rules (requirements) src/scripts/testbot/TESTBOT_RULES.md (lines 69–81)	Specifies required wiring: Python tests need a py_test() including the new file; Go tests require a go_test() in the package BUILD to ensure _test.go files are recognized and run.
Modification Scope Guardrail src/scripts/testbot/TESTBOT_PROMPT.md (lines 60–63)	Restricts allowed edits to test files (.py, .go, .ts/.tsx) and BUILD entries (including py_test and go_test); prohibits changes to source, config, or other non-test files.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

"I hopped through BUILDs with a tiny cheer,
Taught py_test and go_test to appear,
Pointed the runner when tests won't show near,
Guardrails snug so only tests we steer. 🐇"

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'testbot: require go_test BUILD targets for new Go test files' directly and specifically describes the main change—adding guidance to require go_test rules for new Go test files in Bazel BUILD files.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch jiaenr/testbot-go-test-target

---

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 42.93%. Comparing base (c87cc34) to head (19e6a07).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #959   +/-   ##
=======================================
  Coverage   42.93%   42.93%           
=======================================
  Files         218      218           
  Lines       28458    28458           
  Branches     4255     4255           
=======================================
  Hits        12218    12218           
  Misses      15599    15599           
  Partials      641      641           

Flag	Coverage Δ
backend	43.71% <ø> (ø)

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/scripts/testbot/TESTBOT_PROMPT.md`:
- Line 42: The fenced code block containing the Bazel snippet starting with
load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test") is missing a
language tag and triggers markdownlint MD040; update the opening fence from ```
to ```bzl so the block is fenced as ```bzl ... ``` to properly label the code as
Starlark/Bazel.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: f9ac1f4d-2f3d-4e14-a719-e4e22efeb778

📥 Commits

Reviewing files that changed from the base of the PR and between c87cc34 and 2791843.

📒 Files selected for processing (2)

• src/scripts/testbot/TESTBOT_PROMPT.md
• src/scripts/testbot/TESTBOT_RULES.md