better merge of values

cmd/dkl-dir2config/render-context_test.go

@@ -0,0 +1,54 @@
+package main
+
+import (
+	"testing"
+
+	yaml "gopkg.in/yaml.v2"
+)
+
+func TestMerge(t *testing.T) {
+	if v := genericMerge("a", "b"); v != "b" {
+		t.Errorf("got %q", v)
+	}
+
+    if v := unparse(genericMerge(parse(`
+a: t
+b: t
+m:
+  a1: t
+  b1: t
+`), parse(`
+a: s
+c: s
+m:
+  a1: s
+  c1: s
+`))); "\n"+v != `
+a: s
+b: t
+c: s
+m:
+  a1: s
+  b1: t
+  c1: s
+` {
+    t.Errorf("got\n%s", v)
+}
+}
+
+func parse(s string) (r interface{}) {
+	r = map[string]interface{}{}
+	err := yaml.Unmarshal([]byte(s), r)
+	if err != nil {
+		panic(err)
+	}
+	return
+}
+
+func unparse(v interface{}) (s string) {
+	ba, err := yaml.Marshal(v)
+	if err != nil {
+		panic(err)
+	}
+	return string(ba)
+}