Add basic tests for providers

alerting/provider/twilio/twilio_test.go

@@ -1,6 +1,9 @@
 package twilio
 
-import "testing"
+import (
+	"github.com/TwinProduction/gatus/core"
+	"testing"
+)
 
 func TestTwilioAlertProvider_IsValid(t *testing.T) {
 	invalidProvider := AlertProvider{}
@@ -17,3 +20,16 @@ func TestTwilioAlertProvider_IsValid(t *testing.T) {
 		t.Error("provider should've been valid")
 	}
 }
+
+func TestAlertProvider_ToCustomAlertProvider(t *testing.T) {
+	provider := AlertProvider{
+		SID:   "1",
+		Token: "1",
+		From:  "1",
+		To:    "1",
+	}
+	customAlertProvider := provider.ToCustomAlertProvider(&core.Service{}, &core.Alert{}, &core.Result{}, true)
+	if customAlertProvider == nil {
+		t.Error("customAlertProvider shouldn't have been nil")
+	}
+}