systemd: do not fail 'stop' if service unit not installed

If a service unit configuration file doesn't exist on disk, 'systemctl stop'
fails with error code 5 [1]. To keep 'git-bundle-server web-server stop'
from failing when 'web-server start' was not called before it, do not cause
the program to fail when the error code indicates the service isn't
installed. Add a test covering this case.

[1] https://freedesktop.org/software/systemd/man/systemd.exec.html#Process%20Exit%20Codes

Signed-off-by: Victoria Dye <[email protected]>

Author: vdye

internal/daemon/systemd.go

@@ -18,6 +18,8 @@ Type=simple
 ExecStart={{sq_escape .Program}}{{range .Arguments}} {{sq_escape .}}{{end}}
 `
 
+const SystemdUnitNotInstalledErrorCode int = 5
+
 type systemd struct {
 	user       common.UserProvider
 	cmdExec    common.CommandExecutor
@@ -107,7 +109,7 @@ func (s *systemd) Stop(label string) error {
 		return err
 	}
 
-	if exitCode != 0 {
+	if exitCode != 0 && exitCode != SystemdUnitNotInstalledErrorCode {
 		return fmt.Errorf("'systemctl stop' exited with status %d", exitCode)
 	}
 

internal/daemon/systemd_test.go

@@ -313,4 +313,19 @@ func TestSystemd_Stop(t *testing.T) {
 		assert.NotNil(t, err)
 		mock.AssertExpectationsForObjects(t, testCommandExecutor)
 	})
+
+	// Reset the mock structure between tests
+	testCommandExecutor.Mock = mock.Mock{}
+
+	// Test #3: service unit not found still succeeds
+	t.Run("Succeeds if service unit not installed", func(t *testing.T) {
+		testCommandExecutor.On("Run",
+			mock.AnythingOfType("string"),
+			mock.AnythingOfType("[]string"),
+		).Return(daemon.SystemdUnitNotInstalledErrorCode, nil).Once()
+
+		err := systemd.Stop(basicDaemonConfig.Label)
+		assert.Nil(t, err)
+		mock.AssertExpectationsForObjects(t, testCommandExecutor)
+	})
 }