chore: added tests (#1800)

Signed-off-by: Jan-Otto Kröpke <mail@jkroepke.de>

internal/collector/mssql/mssql.go

@@ -272,6 +272,10 @@ func (c *Collector) Build(logger *slog.Logger, _ *mi.Session) error {
 // Collect sends the metric values for each metric
 // to the provided prometheus Metric channel.
 func (c *Collector) Collect(ch chan<- prometheus.Metric) error {
+	if len(c.mssqlInstances) == 0 {
+		return fmt.Errorf("no SQL instances found: %w", perfdata.ErrNoData)
+	}
+
 	errCh := make(chan error, len(c.collectorFns))
 	errs := make([]error, 0, len(c.collectorFns))
 

internal/collector/mssql/mssql_test.go

@@ -25,3 +25,7 @@ import (
 func BenchmarkCollector(b *testing.B) {
 	testutils.FuncBenchmarkCollector(b, mssql.Name, mssql.NewWithFlags)
 }
+
+func TestCollector(t *testing.T) {
+	testutils.TestCollector(t, mssql.New, nil)
+}