fix: ensure embedded postgres cleanup in TestMain

[asonawalla]

Summary

• Remove os.Exit() calls from TestMain functions to allow deferred Stop() calls to execute properly
• Fixes embedded postgres process leaks after test runs

Problem

The TestMain functions in 4 test files were calling os.Exit(code) after m.Run(). In Go, os.Exit() terminates the program immediately without running deferred functions. This meant defer sharedEmbeddedPG.Stop() never executed, leaving orphaned postgres processes after each test package run.

Solution

Go 1.15+ automatically handles the exit code when TestMain returns without calling os.Exit(). By simply removing the os.Exit() calls, the deferred cleanup now executes properly.

Ref: golang/go#34129

Test plan

• Verified no postgres processes running before tests (ps aux | grep postgres)
• Ran go test ./...
• Confirmed postgres processes are cleaned up after tests complete
• go build ./... passes

[Copilot]

Pull request overview

This PR fixes a resource leak issue where embedded PostgreSQL processes were not being cleaned up after test runs. The fix removes os.Exit() calls from TestMain functions in 4 test files, allowing deferred Stop() calls to execute properly. Since Go 1.15+, the testing framework automatically handles exit codes when TestMain returns without calling os.Exit(), making this change both safe and correct.

Changes:

• Removed os.Exit() calls and simplified TestMain to just call m.Run() in 4 test files
• Allows deferred cleanup functions (defer sharedEmbeddedPG.Stop()) to execute properly
• Prevents orphaned PostgreSQL processes after test package runs

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
internal/plan/plan_test.go	Removed os.Exit() to allow deferred postgres cleanup in TestMain
internal/diff/diff_test.go	Removed os.Exit() to allow deferred postgres cleanup in TestMain
cmd/migrate_integration_test.go	Removed os.Exit() to allow deferred postgres cleanup in TestMain
cmd/apply/apply_integration_test.go	Removed os.Exit() to allow deferred postgres cleanup in TestMain

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[tianzhou]

LGTM.