Refactor diff into sub pkg

pkg/util/diff/diff.go

@@ -0,0 +1,121 @@
+/*
+Copyright 2014 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package diff
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"strings"
+	"text/tabwriter"
+
+	"github.com/davecgh/go-spew/spew"
+)
+
+// StringDiff diffs a and b and returns a human readable diff.
+func StringDiff(a, b string) string {
+	ba := []byte(a)
+	bb := []byte(b)
+	out := []byte{}
+	i := 0
+	for ; i < len(ba) && i < len(bb); i++ {
+		if ba[i] != bb[i] {
+			break
+		}
+		out = append(out, ba[i])
+	}
+	out = append(out, []byte("\n\nA: ")...)
+	out = append(out, ba[i:]...)
+	out = append(out, []byte("\n\nB: ")...)
+	out = append(out, bb[i:]...)
+	out = append(out, []byte("\n\n")...)
+	return string(out)
+}
+
+// ObjectDiff writes the two objects out as JSON and prints out the identical part of
+// the objects followed by the remaining part of 'a' and finally the remaining part of 'b'.
+// For debugging tests.
+func ObjectDiff(a, b interface{}) string {
+	ab, err := json.Marshal(a)
+	if err != nil {
+		panic(fmt.Sprintf("a: %v", err))
+	}
+	bb, err := json.Marshal(b)
+	if err != nil {
+		panic(fmt.Sprintf("b: %v", err))
+	}
+	return StringDiff(string(ab), string(bb))
+}
+
+// ObjectGoPrintDiff is like ObjectDiff, but uses go-spew to print the objects,
+// which shows absolutely everything by recursing into every single pointer
+// (go's %#v formatters OTOH stop at a certain point). This is needed when you
+// can't figure out why reflect.DeepEqual is returning false and nothing is
+// showing you differences. This will.
+func ObjectGoPrintDiff(a, b interface{}) string {
+	s := spew.ConfigState{DisableMethods: true}
+	return StringDiff(
+		s.Sprintf("%#v", a),
+		s.Sprintf("%#v", b),
+	)
+}
+
+// ObjectGoPrintSideBySide prints a and b as textual dumps side by side,
+// enabling easy visual scanning for mismatches.
+func ObjectGoPrintSideBySide(a, b interface{}) string {
+	s := spew.ConfigState{
+		Indent: " ",
+		// Extra deep spew.
+		DisableMethods: true,
+	}
+	sA := s.Sdump(a)
+	sB := s.Sdump(b)
+
+	linesA := strings.Split(sA, "\n")
+	linesB := strings.Split(sB, "\n")
+	width := 0
+	for _, s := range linesA {
+		l := len(s)
+		if l > width {
+			width = l
+		}
+	}
+	for _, s := range linesB {
+		l := len(s)
+		if l > width {
+			width = l
+		}
+	}
+	buf := &bytes.Buffer{}
+	w := tabwriter.NewWriter(buf, width, 0, 1, ' ', 0)
+	max := len(linesA)
+	if len(linesB) > max {
+		max = len(linesB)
+	}
+	for i := 0; i < max; i++ {
+		var a, b string
+		if i < len(linesA) {
+			a = linesA[i]
+		}
+		if i < len(linesB) {
+			b = linesB[i]
+		}
+		fmt.Fprintf(w, "%s\t%s\n", a, b)
+	}
+	w.Flush()
+	return buf.String()
+}