Add a reflection based object diff with structured format

pkg/util/diff/diff.go

@@ -20,10 +20,14 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
+	"reflect"
+	"sort"
 	"strings"
 	"text/tabwriter"
 
 	"github.com/davecgh/go-spew/spew"
+
+	"k8s.io/kubernetes/pkg/util/validation/field"
 )
 
 // StringDiff diffs a and b and returns a human readable diff.
@@ -74,6 +78,148 @@ func ObjectGoPrintDiff(a, b interface{}) string {
 	)
 }
 
+func ObjectReflectDiff(a, b interface{}) string {
+	vA, vB := reflect.ValueOf(a), reflect.ValueOf(b)
+	if vA.Type() != vB.Type() {
+		return fmt.Sprintf("type A %T and type B %T do not match", a, b)
+	}
+	diffs := objectReflectDiff(field.NewPath("object"), vA, vB)
+	if len(diffs) == 0 {
+		return ""
+	}
+	out := []string{""}
+	for _, d := range diffs {
+		out = append(out,
+			fmt.Sprintf("%s:", d.path),
+			limit(fmt.Sprintf("  a: %#v", d.a), 80),
+			limit(fmt.Sprintf("  b: %#v", d.b), 80),
+		)
+	}
+	return strings.Join(out, "\n")
+}
+
+func limit(s string, max int) string {
+	if len(s) > max {
+		return s[:max]
+	}
+	return s
+}
+
+func public(s string) bool {
+	if len(s) == 0 {
+		return false
+	}
+	return s[:1] == strings.ToUpper(s[:1])
+}
+
+type diff struct {
+	path *field.Path
+	a, b interface{}
+}
+
+type orderedDiffs []diff
+
+func (d orderedDiffs) Len() int      { return len(d) }
+func (d orderedDiffs) Swap(i, j int) { d[i], d[j] = d[j], d[i] }
+func (d orderedDiffs) Less(i, j int) bool {
+	a, b := d[i].path.String(), d[j].path.String()
+	if a < b {
+		return true
+	}
+	return false
+}
+
+func objectReflectDiff(path *field.Path, a, b reflect.Value) []diff {
+	switch a.Type().Kind() {
+	case reflect.Struct:
+		var changes []diff
+		for i := 0; i < a.Type().NumField(); i++ {
+			if !public(a.Type().Field(i).Name) {
+				if reflect.DeepEqual(a.Interface(), b.Interface()) {
+					return nil
+				}
+				return []diff{{path: path, a: fmt.Sprintf("%#v", a), b: fmt.Sprintf("%#v", b)}}
+			}
+			if sub := objectReflectDiff(path.Child(a.Type().Field(i).Name), a.Field(i), b.Field(i)); len(sub) > 0 {
+				changes = append(changes, sub...)
+			}
+		}
+		return changes
+	case reflect.Ptr:
+		if a.IsNil() || b.IsNil() {
+			switch {
+			case a.IsNil() && b.IsNil():
+				return nil
+			case a.IsNil():
+				return []diff{{path: path, a: nil, b: b.Interface()}}
+			default:
+				return []diff{{path: path, a: a.Interface(), b: nil}}
+			}
+		}
+		return objectReflectDiff(path, a.Elem(), b.Elem())
+	case reflect.Chan:
+		if !reflect.DeepEqual(a.Interface(), b.Interface()) {
+			return []diff{{path: path, a: a.Interface(), b: b.Interface()}}
+		}
+		return nil
+	case reflect.Slice:
+		if reflect.DeepEqual(a, b) {
+			return nil
+		}
+		lA, lB := a.Len(), b.Len()
+		l := lA
+		if lB < lA {
+			l = lB
+		}
+		for i := 0; i < l; i++ {
+			if !reflect.DeepEqual(a.Index(i), b.Index(i)) {
+				return objectReflectDiff(path.Index(i), a.Index(i), b.Index(i))
+			}
+		}
+		var diffs []diff
+		for i := l; l < lA; i++ {
+			diffs = append(diffs, diff{path: path.Index(i), a: a.Index(i), b: nil})
+		}
+		for i := l; l < lB; i++ {
+			diffs = append(diffs, diff{path: path.Index(i), a: nil, b: b.Index(i)})
+		}
+		return diffs
+	case reflect.Map:
+		if reflect.DeepEqual(a, b) {
+			return nil
+		}
+		aKeys := make(map[interface{}]interface{})
+		for _, key := range a.MapKeys() {
+			aKeys[key.Interface()] = a.MapIndex(key).Interface()
+		}
+		var missing []diff
+		for _, key := range b.MapKeys() {
+			if _, ok := aKeys[key.Interface()]; ok {
+				delete(aKeys, key.Interface())
+				if reflect.DeepEqual(a.MapIndex(key).Interface(), b.MapIndex(key).Interface()) {
+					continue
+				}
+				missing = append(missing, diff{path: path.Key(fmt.Sprintf("%s", key.Interface())), a: a.MapIndex(key).Interface(), b: b.MapIndex(key).Interface()})
+				continue
+			}
+			missing = append(missing, diff{path: path.Key(fmt.Sprintf("%s", key.Interface())), a: nil, b: b.MapIndex(key).Interface()})
+		}
+		for key, value := range aKeys {
+			missing = append(missing, diff{path: path.Key(fmt.Sprintf("%s", key)), a: value, b: nil})
+		}
+		sort.Sort(orderedDiffs(missing))
+		return missing
+	default:
+		if reflect.DeepEqual(a.Interface(), b.Interface()) {
+			return nil
+		}
+		if !a.CanInterface() {
+			return []diff{{path: path, a: fmt.Sprintf("%#v", a), b: fmt.Sprintf("%#v", b)}}
+		}
+		return []diff{{path: path, a: a.Interface(), b: b.Interface()}}
+	}
+}
+
 // ObjectGoPrintSideBySide prints a and b as textual dumps side by side,
 // enabling easy visual scanning for mismatches.
 func ObjectGoPrintSideBySide(a, b interface{}) string {