import transform will not overwrite existing records. (#34)

fixes #33

normalize/importTransform_test.go

@@ -0,0 +1,42 @@
+package normalize
+
+import (
+	"github.com/StackExchange/dnscontrol/models"
+	"testing"
+)
+
+func TestImportTransform(t *testing.T) {
+
+	const transformDouble = "0.0.0.0~1.1.1.1~~9.0.0.0,10.0.0.0"
+	const transformSingle = "0.0.0.0~1.1.1.1~~8.0.0.0"
+	src := &models.DomainConfig{
+		Name: "stackexchange.com",
+		Records: []*models.RecordConfig{
+			{Type: "A", Name: "*", NameFQDN: "*.stackexchange.com", Target: "0.0.2.2"},
+			{Type: "A", Name: "www", NameFQDN: "", Target: "0.0.1.1"},
+		},
+	}
+	dst := &models.DomainConfig{
+		Name: "internal",
+		Records: []*models.RecordConfig{
+			{Type: "A", Name: "*.stackexchange.com", NameFQDN: "*.stackexchange.com.internal", Target: "0.0.3.3", Metadata: map[string]string{"transform_table": transformSingle}},
+			{Type: "IMPORT_TRANSFORM", Name: "@", Target: "stackexchange.com", Metadata: map[string]string{"transform_table": transformDouble}},
+		},
+	}
+	cfg := &models.DNSConfig{
+		Domains: []*models.DomainConfig{src, dst},
+	}
+	if errs := NormalizeAndValidateConfig(cfg); len(errs) != 0 {
+		for _, err := range errs {
+			t.Error(err)
+		}
+		t.FailNow()
+	}
+	d := cfg.FindDomain("internal")
+	if len(d.Records) != 3 {
+		for _, r := range d.Records {
+			t.Error(r)
+		}
+		t.Fatalf("Expected 3 records in internal, but got %d", len(d.Records))
+	}
+}

normalize/validate.go

@@ -147,6 +147,9 @@ func import_transform(src_domain, dst_domain *models.DomainConfig, transforms []
 	// 4. For As, change the target as described the transforms.
 
 	for _, rec := range src_domain.Records {
+		if dst_domain.HasRecordTypeName(rec.Type, rec.NameFQDN) {
+			continue
+		}
 		newRec := func() *models.RecordConfig {
 			rec2, _ := rec.Copy()
 			rec2.Name = rec2.NameFQDN