fix: register shutdown signals before startup

main_test.go

@@ -3,6 +3,9 @@ package main
 import (
 	"context"
 	"errors"
+	"go/ast"
+	"go/parser"
+	"go/token"
 	"net/http"
 	"os"
 	"reflect"
@@ -11,6 +14,63 @@ import (
 	"time"
 )
 
+func TestRunRegistersSignalsBeforeStartingResources(t *testing.T) {
+	fset := token.NewFileSet()
+	file, err := parser.ParseFile(fset, "main.go", nil, 0)
+	if err != nil {
+		t.Fatalf("parse main.go: %v", err)
+	}
+
+	var runBody *ast.BlockStmt
+	for _, declaration := range file.Decls {
+		function, ok := declaration.(*ast.FuncDecl)
+		if ok && function.Name.Name == "run" {
+			runBody = function.Body
+			break
+		}
+	}
+	if runBody == nil {
+		t.Fatal("main.go does not define run")
+	}
+
+	positions := make(map[string]token.Pos)
+	ast.Inspect(runBody, func(node ast.Node) bool {
+		call, ok := node.(*ast.CallExpr)
+		if !ok {
+			return true
+		}
+		selector, ok := call.Fun.(*ast.SelectorExpr)
+		if !ok {
+			return true
+		}
+		owner, ok := selector.X.(*ast.Ident)
+		if !ok {
+			return true
+		}
+		name := owner.Name + "." + selector.Sel.Name
+		switch name {
+		case "signal.Notify", "db.NewPool", "queue.Start", "srv.ListenAndServe":
+			positions[name] = call.Pos()
+		}
+		return true
+	})
+
+	notifyPos, ok := positions["signal.Notify"]
+	if !ok {
+		t.Fatal("run does not register for shutdown signals")
+	}
+	for _, start := range []string{"db.NewPool", "queue.Start", "srv.ListenAndServe"} {
+		startPos, ok := positions[start]
+		if !ok {
+			t.Fatalf("run does not call %s", start)
+		}
+		if notifyPos >= startPos {
+			t.Errorf("signal.Notify at line %d must precede %s at line %d",
+				fset.Position(notifyPos).Line, start, fset.Position(startPos).Line)
+		}
+	}
+}
+
 func TestWaitForShutdownReturnsListenerError(t *testing.T) {
 	listenErr := errors.New("listen failed")
 	serverErr := make(chan error, 1)