Add tests

internal/system/system.go

@@ -20,6 +20,7 @@ func GetSignalChannel() chan os.Signal {
 	if signalSingleton == nil {
 		sigs = make(chan os.Signal, 1)
 		signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
+		signalSingleton = new(byte)
 	}
 	return sigs
 }

internal/system/system_test.go

@@ -0,0 +1,58 @@
+package system
+
+import (
+	"errors"
+	"os"
+	"sync"
+	"testing"
+)
+
+func Test_System(t *testing.T) {
+	t.Run("Critical error", func(t *testing.T) {
+		var exitCode *int
+		exitFunc = func(code int) {
+			exitCode = &code
+		}
+
+		CriticalError(errors.New("foo"))
+
+		if exitCode == nil || *exitCode != 1 {
+			t.Errorf("Expected exit code 1, got %d", exitCode)
+		}
+	})
+
+	t.Run("Error", func(t *testing.T) {
+		var exitCode *int
+		exitFunc = func(code int) {
+			exitCode = &code
+		}
+
+		wg := sync.WaitGroup{}
+		var signal *os.Signal
+
+		s := GetSignalChannel()
+
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			current := <-s
+			signal = &current
+		}()
+
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			Error(errors.New("foo"))
+		}()
+
+		wg.Wait()
+
+		if exitCode != nil {
+			t.Error("Exit should not be called")
+		}
+
+		if signal == nil {
+			t.Error("Signal should not be called")
+		}
+	})
+}