libs/os: add test case for TrapSignal (#5646)

libs/os/os.go

@@ -13,19 +13,19 @@ type logger interface {
 	Info(msg string, keyvals ...interface{})
 }
 
-// TrapSignal catches the SIGTERM/SIGINT and executes cb function. After that it exits
-// with code 0.
+// TrapSignal catches SIGTERM and SIGINT, executes the cleanup function,
+// and exits with code 0.
 func TrapSignal(logger logger, cb func()) {
 	c := make(chan os.Signal, 1)
 	signal.Notify(c, os.Interrupt, syscall.SIGTERM)
+
 	go func() {
-		for sig := range c {
-			logger.Info(fmt.Sprintf("captured %v, exiting...", sig))
-			if cb != nil {
-				cb()
-			}
-			os.Exit(0)
+		sig := <-c
+		logger.Info(fmt.Sprintf("captured %v, exiting...", sig))
+		if cb != nil {
+			cb()
 		}
+		os.Exit(0)
 	}()
 }
 

libs/os/os_test.go

@@ -1,11 +1,15 @@
-package os
+package os_test
 
 import (
 	"bytes"
 	"fmt"
 	"io/ioutil"
 	"os"
+	"os/exec"
 	"testing"
+	"time"
+
+	tmos "github.com/tendermint/tendermint/libs/os"
 )
 
 func TestCopyFile(t *testing.T) {
@@ -20,7 +24,7 @@ func TestCopyFile(t *testing.T) {
 	}
 
 	copyfile := fmt.Sprintf("%s.copy", tmpfile.Name())
-	if err := CopyFile(tmpfile.Name(), copyfile); err != nil {
+	if err := tmos.CopyFile(tmpfile.Name(), copyfile); err != nil {
 		t.Fatal(err)
 	}
 	if _, err := os.Stat(copyfile); os.IsNotExist(err) {
@@ -35,3 +39,51 @@ func TestCopyFile(t *testing.T) {
 	}
 	os.Remove(copyfile)
 }
+
+func TestTrapSignal(t *testing.T) {
+	if os.Getenv("TM_TRAP_SIGNAL_TEST") == "1" {
+		t.Log("inside test process")
+		killer()
+		return
+	}
+
+	cmd := exec.Command(os.Args[0], "-test.run="+t.Name())
+	mockStderr := bytes.NewBufferString("")
+	cmd.Env = append(os.Environ(), "TM_TRAP_SIGNAL_TEST=1")
+	cmd.Stderr = mockStderr
+
+	err := cmd.Run()
+	if err == nil {
+		wantStderr := "exiting"
+		if mockStderr.String() != wantStderr {
+			t.Fatalf("stderr: want %q, got %q", wantStderr, mockStderr.String())
+		}
+
+		return
+	}
+
+	if e, ok := err.(*exec.ExitError); ok && !e.Success() {
+		t.Fatalf("wrong exit code, want 0, got %d", e.ExitCode())
+	}
+
+	t.Fatal("this error should not be triggered")
+
+}
+
+type mockLogger struct{}
+
+func (ml mockLogger) Info(msg string, keyvals ...interface{}) {}
+
+func killer() {
+	logger := mockLogger{}
+
+	tmos.TrapSignal(logger, func() { _, _ = fmt.Fprintf(os.Stderr, "exiting") })
+	time.Sleep(1 * time.Second)
+
+	// use Kill() to test SIGTERM
+	if err := tmos.Kill(); err != nil {
+		panic(err)
+	}
+
+	time.Sleep(1 * time.Second)
+}