Add basic unittest for templating engine

internal/templating/engine_test.go

@@ -0,0 +1,22 @@
+package templating
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestEngineAlternateSeparator(t *testing.T) {
+	defaultTemplate, _ := NewDefaultTemplateWithPattern("topic*")
+	engine, err := NewEngine("_", defaultTemplate, []string{
+		"/ /*/*/* /measurement/origin/measurement*",
+	})
+	require.NoError(t, err)
+	name, tags, field, err := engine.Apply("/telegraf/host01/cpu")
+	require.NoError(t, err)
+	require.Equal(t, "telegraf_cpu", name)
+	require.Equal(t, map[string]string{
+		"origin": "host01",
+	}, tags)
+	require.Equal(t, "", field)
+}