add boilerplate reduction struct field copier

pkg/conversion/converter_test.go

@@ -290,3 +290,95 @@ func TestConverter_flags(t *testing.T) {
 		}
 	}
 }
+
+func TestConverter_FieldRename(t *testing.T) {
+	type WeirdMeta struct {
+		Name string
+		Type string
+	}
+	type NameMeta struct {
+		Name string
+	}
+	type TypeMeta struct {
+		Type string
+	}
+	type A struct {
+		WeirdMeta
+	}
+	type B struct {
+		TypeMeta
+		NameMeta
+	}
+
+	c := NewConverter()
+	err := c.SetStructFieldCopy(WeirdMeta{}, "WeirdMeta", TypeMeta{}, "TypeMeta")
+	if err != nil {
+		t.Fatalf("unexpected error %v", err)
+	}
+	err = c.SetStructFieldCopy(WeirdMeta{}, "WeirdMeta", NameMeta{}, "NameMeta")
+	if err != nil {
+		t.Fatalf("unexpected error %v", err)
+	}
+	err = c.SetStructFieldCopy(TypeMeta{}, "TypeMeta", WeirdMeta{}, "WeirdMeta")
+	if err != nil {
+		t.Fatalf("unexpected error %v", err)
+	}
+	err = c.SetStructFieldCopy(NameMeta{}, "NameMeta", WeirdMeta{}, "WeirdMeta")
+	if err != nil {
+		t.Fatalf("unexpected error %v", err)
+	}
+	c.Debug = t
+
+	aVal := &A{
+		WeirdMeta: WeirdMeta{
+			Name: "Foo",
+			Type: "Bar",
+		},
+	}
+
+	bVal := &B{
+		TypeMeta: TypeMeta{"Bar"},
+		NameMeta: NameMeta{"Foo"},
+	}
+
+	table := map[string]struct {
+		from, to, expect interface{}
+		flags            FieldMatchingFlags
+	}{
+		"to": {
+			aVal,
+			&B{},
+			bVal,
+			AllowDifferentFieldTypeNames | SourceToDest | IgnoreMissingFields,
+		},
+		"from": {
+			bVal,
+			&A{},
+			aVal,
+			AllowDifferentFieldTypeNames | SourceToDest,
+		},
+		"toDestFirst": {
+			aVal,
+			&B{},
+			bVal,
+			AllowDifferentFieldTypeNames,
+		},
+		"fromDestFirst": {
+			bVal,
+			&A{},
+			aVal,
+			AllowDifferentFieldTypeNames | IgnoreMissingFields,
+		},
+	}
+
+	for name, item := range table {
+		err := c.Convert(item.from, item.to, item.flags, nil)
+		if err != nil {
+			t.Errorf("%v: unexpected error: %v", name, err)
+			continue
+		}
+		if e, a := item.expect, item.to; !reflect.DeepEqual(e, a) {
+			t.Errorf("%v: unexpected diff: %v", name, objDiff(e, a))
+		}
+	}
+}