command/fix: fixer for iso_md5 change

command/fix/fixer.go

+package fix
+
+// A Fixer is something that can perform a fix operation on a template.
+type Fixer interface {
+	// Fix takes a raw map structure input, potentially transforms it
+	// in some way, and returns the new, transformed structure. The
+	// Fix method is allowed to mutate the input.
+	Fix(input map[string]interface{}) (map[string]interface{}, error)
+}
+
+// Fixers is the map of all available fixers, by name.
+var Fixers map[string]Fixer
+
+func init() {
+	Fixers = map[string]Fixer{
+		"iso-md5": new(FixerISOMD5),
+	}
+}

command/fix/fixer_iso_md5.go

+package fix
+
+import (
+	"github.com/mitchellh/mapstructure"
+)
+
+// FixerISOMD5 is a Fixer that replaces the "iso_md5" configuration key
+// with the newer "iso_checksum" and "iso_checksum_type" within builders.
+type FixerISOMD5 struct{}
+
+func (FixerISOMD5) Fix(input map[string]interface{}) (map[string]interface{}, error) {
+	// Our template type we'll use for this fixer only
+	type template struct {
+		Builders []map[string]interface{}
+	}
+
+	// Decode the input into our structure, if we can
+	var tpl template
+	if err := mapstructure.Decode(input, &tpl); err != nil {
+		return nil, err
+	}
+
+	// Go through each builder and replace the iso_md5 if we can
+	for _, builder := range tpl.Builders {
+		md5raw, ok := builder["iso_md5"]
+		if !ok {
+			continue
+		}
+
+		md5, ok := md5raw.(string)
+		if !ok {
+			// TODO: error?
+			continue
+		}
+
+		delete(builder, "iso_md5")
+		builder["iso_checksum"] = md5
+		builder["iso_checksum_type"] = "md5"
+	}
+
+	input["builders"] = tpl.Builders
+	return input, nil
+}

command/fix/fixer_iso_md5_test.go

+package fix
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestFixerISOMD5_Impl(t *testing.T) {
+	var raw interface{}
+	raw = new(FixerISOMD5)
+	if _, ok := raw.(Fixer); !ok {
+		t.Fatalf("must be a Fixer")
+	}
+}
+
+func TestFixerISOMD5_Fix(t *testing.T) {
+	var f FixerISOMD5
+
+	input := map[string]interface{}{
+		"builders": []interface{}{
+			map[string]string{
+				"type":    "foo",
+				"iso_md5": "bar",
+			},
+		},
+	}
+
+	expected := map[string]interface{}{
+		"builders": []map[string]interface{}{
+			map[string]interface{}{
+				"type":              "foo",
+				"iso_checksum":      "bar",
+				"iso_checksum_type": "md5",
+			},
+		},
+	}
+
+	output, err := f.Fix(input)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	if !reflect.DeepEqual(output, expected) {
+		t.Fatalf("unexpected: %#v\nexpected: %#v\n", output, expected)
+	}
+}