fix: improve environment variable handling in debug mode

- Add a check for non-empty environment variables when debug mode is enabled
- Remove redundant environment variable output in tests

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

plugin.go

@@ -125,7 +125,7 @@ func (p Plugin) exec(host string, wg *sync.WaitGroup, errChannel chan error) {
 
 	p.Config.Script = append(env, p.scriptCommands()...)
 
-	if p.Config.Debug {
+	if p.Config.Debug && len(env) > 0 {
 		p.log(host, "======ENV======")
 		p.log(host, strings.Join(env, "\n"))
 		p.log(host, "======END======")

plugin_test.go

@@ -365,9 +365,6 @@ func TestCommandOutput(t *testing.T) {
 			whoami
 			uname
 			localhost: ======END======
-			localhost: ======ENV======
-			localhost:
-			localhost: ======END======
 			localhost: out: /home/drone-scp
 			localhost: out: drone-scp
 			localhost: out: Linux
@@ -376,9 +373,6 @@ func TestCommandOutput(t *testing.T) {
 			whoami
 			uname
 			127.0.0.1: ======END======
-			127.0.0.1: ======ENV======
-			127.0.0.1:
-			127.0.0.1: ======END======
 			127.0.0.1: out: /home/drone-scp
 			127.0.0.1: out: drone-scp
 			127.0.0.1: out: Linux