From 04cdfd42973bb9c8589fd6a731800cf222fde1a9 Mon Sep 17 00:00:00 2001
From: Alexander Staubo <alex@purefiction.net>
Date: Fri, 28 Oct 2016 13:58:48 -0400
Subject: [PATCH] Adds new config options:

DisablePointerAddresses: Specifies whether to disable the printing of
pointer addresses.

DisableCapacities specifies whether to disable the printing of capacities
for arrays, slices, maps and channels.

These are useful when diffing data structures in tests. Printing pointers
and capacities would otherwise lead to false negatives.
---
 spew/config.go    |  9 +++++++++
 spew/dump.go      |  6 +++---
 spew/spew_test.go | 11 +++++++++++
 3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/spew/config.go b/spew/config.go
index 5552827..9db83c6 100644
--- a/spew/config.go
+++ b/spew/config.go
@@ -67,6 +67,15 @@ type ConfigState struct {
 	// Google App Engine or with the "safe" build tag specified.
 	DisablePointerMethods bool
 
+	// DisablePointerAddresses specifies whether to disable the printing of
+	// pointer addresses. This is useful when diffing data structures in tests.
+	DisablePointerAddresses bool
+
+	// DisableCapacities specifies whether to disable the printing of capacities
+	// for arrays, slices, maps and channels. This is useful when diffing
+	// data structures in tests.
+	DisableCapacities bool
+
 	// ContinueOnMethod specifies whether or not recursion should continue once
 	// a custom error or Stringer interface is invoked.  The default, false,
 	// means it will print the results of invoking the custom error or Stringer
diff --git a/spew/dump.go b/spew/dump.go
index a0ff95e..95f9dbf 100644
--- a/spew/dump.go
+++ b/spew/dump.go
@@ -129,7 +129,7 @@ func (d *dumpState) dumpPtr(v reflect.Value) {
 	d.w.Write(closeParenBytes)
 
 	// Display pointer information.
-	if len(pointerChain) > 0 {
+	if !d.cs.DisablePointerAddresses && len(pointerChain) > 0 {
 		d.w.Write(openParenBytes)
 		for i, addr := range pointerChain {
 			if i > 0 {
@@ -282,13 +282,13 @@ func (d *dumpState) dump(v reflect.Value) {
 	case reflect.Map, reflect.String:
 		valueLen = v.Len()
 	}
-	if valueLen != 0 || valueCap != 0 {
+	if valueLen != 0 || !d.cs.DisableCapacities && valueCap != 0 {
 		d.w.Write(openParenBytes)
 		if valueLen != 0 {
 			d.w.Write(lenEqualsBytes)
 			printInt(d.w, int64(valueLen), 10)
 		}
-		if valueCap != 0 {
+		if !d.cs.DisableCapacities && valueCap != 0 {
 			if valueLen != 0 {
 				d.w.Write(spaceBytes)
 			}
diff --git a/spew/spew_test.go b/spew/spew_test.go
index dbbc085..f1f6b71 100644
--- a/spew/spew_test.go
+++ b/spew/spew_test.go
@@ -130,12 +130,19 @@ func initSpewTests() {
 	scsNoPmethods := &spew.ConfigState{Indent: " ", DisablePointerMethods: true}
 	scsMaxDepth := &spew.ConfigState{Indent: " ", MaxDepth: 1}
 	scsContinue := &spew.ConfigState{Indent: " ", ContinueOnMethod: true}
+	scsNoPtrAddr := &spew.ConfigState{DisablePointerAddresses: true}
+	scsNoCap := &spew.ConfigState{DisableCapacities: true}
 
 	// Variables for tests on types which implement Stringer interface with and
 	// without a pointer receiver.
 	ts := stringer("test")
 	tps := pstringer("test")
 
+	type ptrTester struct {
+		s *struct{}
+	}
+	tptr := &ptrTester{s: &struct{}{}}
+
 	// depthTester is used to test max depth handling for structs, array, slices
 	// and maps.
 	type depthTester struct {
@@ -192,6 +199,10 @@ func initSpewTests() {
 		{scsContinue, fCSFprint, "", te, "(error: 10) 10"},
 		{scsContinue, fCSFdump, "", te, "(spew_test.customError) " +
 			"(error: 10) 10\n"},
+		{scsNoPtrAddr, fCSFprint, "", tptr, "<*>{<*>{}}"},
+		{scsNoPtrAddr, fCSSdump, "", tptr, "(*spew_test.ptrTester)({\ns: (*struct {})({\n})\n})\n"},
+		{scsNoCap, fCSSdump, "", make([]string, 0, 10), "([]string) {\n}\n"},
+		{scsNoCap, fCSSdump, "", make([]string, 1, 10), "([]string) (len=1) {\n(string) \"\"\n}\n"},
 	}
 }