From 5671d803466badd32a5ef37d6758784e19b65826 Mon Sep 17 00:00:00 2001
From: seankane-msft <seankane@microsoft.com>
Date: Tue, 3 Aug 2021 14:30:14 -0400
Subject: [PATCH 01/13] add type def for ETag

---
 sdk/azcore/core.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sdk/azcore/core.go b/sdk/azcore/core.go
index ff915e59eae3..b30a1bb2f374 100644
--- a/sdk/azcore/core.go
+++ b/sdk/azcore/core.go
@@ -203,3 +203,6 @@ func IsNullValue(v interface{}) bool {
 	// no sentinel object for this *t
 	return false
 }
+
+// ETag is a property used for optimistic concurrency during updates
+type ETag string

From bd1dfcd637bcab6936ad7d4a937bde15ba93f036 Mon Sep 17 00:00:00 2001
From: seankane-msft <seankane@microsoft.com>
Date: Thu, 5 Aug 2021 13:47:22 -0400
Subject: [PATCH 02/13] adding etag specific files and more functionality

---
 sdk/azcore/core.go      |  5 +----
 sdk/azcore/etag.go      | 41 +++++++++++++++++++++++++++++++++++++++++
 sdk/azcore/etag_test.go | 37 +++++++++++++++++++++++++++++++++++++
 3 files changed, 79 insertions(+), 4 deletions(-)
 create mode 100644 sdk/azcore/etag.go
 create mode 100644 sdk/azcore/etag_test.go

diff --git a/sdk/azcore/core.go b/sdk/azcore/core.go
index b30a1bb2f374..1219c5f419c8 100644
--- a/sdk/azcore/core.go
+++ b/sdk/azcore/core.go
@@ -202,7 +202,4 @@ func IsNullValue(v interface{}) bool {
 	}
 	// no sentinel object for this *t
 	return false
-}
-
-// ETag is a property used for optimistic concurrency during updates
-type ETag string
+}
\ No newline at end of file
diff --git a/sdk/azcore/etag.go b/sdk/azcore/etag.go
new file mode 100644
index 000000000000..07e9e7fcac82
--- /dev/null
+++ b/sdk/azcore/etag.go
@@ -0,0 +1,41 @@
+// +build go1.13
+
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+package azcore
+
+import (
+	"strings"
+)
+
+// ETag is a property used for optimistic concurrency during updates
+type ETag struct {
+	value *string
+}
+
+func NewEtag(value string) *ETag {
+	return &ETag{value: &value}
+}
+
+func (e ETag) Equals(right ETag) bool {
+	// ETags are != if one value is null
+	if *e.value == "" || *right.value == "" {
+		// If both are null, they are considered equal
+		return *e.value == *right.value
+	}
+
+	return true
+}
+
+func (e ETag) String() string {
+	return *e.value
+}
+
+func (e ETag) HasValue() bool {
+	return e.value != nil
+}
+
+func (e ETag) IsWeak() bool {
+	return e.value != nil && len(*e.value) >= 4 && strings.HasPrefix(*e.value, "W/\"") && strings.HasSuffix(*e.value, "\"")
+}
diff --git a/sdk/azcore/etag_test.go b/sdk/azcore/etag_test.go
new file mode 100644
index 000000000000..497c583a6207
--- /dev/null
+++ b/sdk/azcore/etag_test.go
@@ -0,0 +1,37 @@
+// +build go1.13
+
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+package azcore
+
+import "testing"
+
+func TestEtagEquals(t *testing.T) {
+	e1 := NewEtag("tag")
+	if e1.String() != "tag" {
+		t.Fatalf("ETag values are not equal")
+	}
+
+	e2 := NewEtag("\"tag\"")
+	if e2.String() != "\"tag\"" {
+		t.Fatalf("ETag values are not equal")
+	}
+
+	e3 := NewEtag("W/\"weakETag\"")
+	if e3.String() != "W/\"weakETag\"" {
+		t.Fatalf("ETag values are not equal")
+	}
+	if !e3.IsWeak() {
+		t.Fatalf("ETag is expected to be weak")
+	}
+
+	strongETag := NewEtag("\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
+	if strongETag.String() != "\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"" {
+		t.Fatalf("Etag values are not equal")
+	}
+}
+
+func TestEtagWeak(t *testing.T) {
+	
+}
\ No newline at end of file

From 8e0a9f95a34bc407ccfadaa1beb0c5cd4b8bd217 Mon Sep 17 00:00:00 2001
From: seankane-msft <seankane@microsoft.com>
Date: Thu, 5 Aug 2021 15:20:16 -0400
Subject: [PATCH 03/13] testing weak

---
 sdk/azcore/etag.go      | 39 +++++++++++++++--
 sdk/azcore/etag_test.go | 92 +++++++++++++++++++++++++++++++++++++----
 2 files changed, 120 insertions(+), 11 deletions(-)

diff --git a/sdk/azcore/etag.go b/sdk/azcore/etag.go
index 07e9e7fcac82..15d0a4c7b16d 100644
--- a/sdk/azcore/etag.go
+++ b/sdk/azcore/etag.go
@@ -14,18 +14,42 @@ type ETag struct {
 	value *string
 }
 
-func NewEtag(value string) *ETag {
+func NewETag(value string) *ETag {
 	return &ETag{value: &value}
 }
 
-func (e ETag) Equals(right ETag) bool {
+type ComparisonType string
+
+const (
+	Strong         ComparisonType = "strong"
+	WeakComparison ComparisonType = "weak"
+)
+
+func (e ETag) Equals(right ETag, comparisonKind ComparisonType) bool {
 	// ETags are != if one value is null
 	if *e.value == "" || *right.value == "" {
 		// If both are null, they are considered equal
 		return *e.value == *right.value
 	}
 
-	return true
+	if comparisonKind == Strong {
+		return !e.IsWeak() && right.IsWeak() && *e.value == *right.value
+	}
+
+	leftStart := e.getStart()
+	rightStart := right.getStart()
+
+	leftValue := (*e.value)[leftStart:]
+	rightValue := (*e.value)[rightStart:]
+
+	return leftValue == rightValue
+}
+
+func (e ETag) getStart() int {
+	if e.IsWeak() {
+		return 2
+	}
+	return 0
 }
 
 func (e ETag) String() string {
@@ -37,5 +61,14 @@ func (e ETag) HasValue() bool {
 }
 
 func (e ETag) IsWeak() bool {
+	// fmt.Println(e.value != nil)
+	// fmt.Println(len(*e.value) >= 4)
+	// fmt.Println(strings.HasPrefix(*e.value, "W/\""))
+	// fmt.Println(strings.HasSuffix(*e.value, "\""))
 	return e.value != nil && len(*e.value) >= 4 && strings.HasPrefix(*e.value, "W/\"") && strings.HasSuffix(*e.value, "\"")
 }
+
+func ETagAny() *ETag {
+	any := "*"
+	return &ETag{value: &any}
+}
diff --git a/sdk/azcore/etag_test.go b/sdk/azcore/etag_test.go
index 497c583a6207..e6953671fe5f 100644
--- a/sdk/azcore/etag_test.go
+++ b/sdk/azcore/etag_test.go
@@ -5,20 +5,23 @@
 
 package azcore
 
-import "testing"
+import (
+	"fmt"
+	"testing"
+)
 
 func TestEtagEquals(t *testing.T) {
-	e1 := NewEtag("tag")
+	e1 := NewETag("tag")
 	if e1.String() != "tag" {
 		t.Fatalf("ETag values are not equal")
 	}
 
-	e2 := NewEtag("\"tag\"")
+	e2 := NewETag("\"tag\"")
 	if e2.String() != "\"tag\"" {
 		t.Fatalf("ETag values are not equal")
 	}
 
-	e3 := NewEtag("W/\"weakETag\"")
+	e3 := NewETag("W/\"weakETag\"")
 	if e3.String() != "W/\"weakETag\"" {
 		t.Fatalf("ETag values are not equal")
 	}
@@ -26,12 +29,85 @@ func TestEtagEquals(t *testing.T) {
 		t.Fatalf("ETag is expected to be weak")
 	}
 
-	strongETag := NewEtag("\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
+	strongETag := NewETag("\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
 	if strongETag.String() != "\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"" {
 		t.Fatalf("Etag values are not equal")
 	}
+
+	if ETagAny().IsWeak() {
+		t.Fatalf("ETagAny should not be weak")
+	}
 }
 
-func TestEtagWeak(t *testing.T) {
-	
-}
\ No newline at end of file
+func TestETagWeak(t *testing.T) {
+	et1 := NewETag("tag")
+	if !et1.IsWeak() {
+		t.Fatalf("Expected to be weak")
+	}
+
+	et2 := NewETag("\"tag\"")
+	if !et2.IsWeak() {
+		t.Fatalf("Expected to be weak")
+	}
+
+	et3 := NewETag("W/\"weakETag\"")
+	if !et3.IsWeak() {
+		t.Fatalf("Expected to be weak")
+	}
+
+	et4 := NewETag("W/\"\"")
+	if !et4.IsWeak() {
+		t.Fatalf("Expected to be weak")
+	}
+
+	et5 := ETagAny()
+	if !et5.IsWeak() {
+		t.Fatalf("Expected to be weak")
+	}
+}
+
+/*
+
+func TestEtagStars(t *testing.T) {
+	anyETag := ETagAny()
+	star := NewETag("*")
+	// weakStar := NewETag("W\"*\"")
+	quotedStar := NewETag("\"*\"")
+
+	strongETag := NewETag("\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
+
+	if anyETag.Equals(*anyETag, Strong) {
+		t.Fatalf("Expected etags to be equal")
+	}
+	if anyETag.Equals(*ETagAny(), Strong) {
+		t.Fatalf("Expected etags to be equal")
+	}
+	if anyETag.Equals(*strongETag, Strong) {
+		t.Fatalf("Expected etags to be equal")
+	}
+
+	// expectEqual(t, star, star)
+	// expectEqual(t, star, ETagAny())
+	// expectEqual(t, star, anyETag)
+
+	// expectNotEqual(t, star, weakStar)
+	// expectNotEqual(t, weakStar, ETagAny())
+	// expectNotEqual(t, quotedStar, weakStar)
+
+	expectNotEqual(t, star, quotedStar)
+	expectEqual(t, anyETag, star)
+}
+*/
+
+func expectEqual(t *testing.T, left *ETag, right *ETag) {
+	if !left.Equals(*right, Strong) {
+		fmt.Println(*left.value, *right.value)
+		t.Fatalf("Expected etags to be equal")
+	}
+}
+
+func expectNotEqual(t *testing.T, left *ETag, right *ETag) {
+	if left.Equals(*right, Strong) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+}

From 0390d0092b06e40bae0757037e0d68a5caa15d28 Mon Sep 17 00:00:00 2001
From: seankane-msft <seankane@microsoft.com>
Date: Thu, 5 Aug 2021 15:34:28 -0400
Subject: [PATCH 04/13] testing for etag equality

---
 sdk/azcore/etag.go      |  2 +-
 sdk/azcore/etag_test.go | 69 +++++++++++++++++++++--------------------
 2 files changed, 37 insertions(+), 34 deletions(-)

diff --git a/sdk/azcore/etag.go b/sdk/azcore/etag.go
index 15d0a4c7b16d..61e978bd3e06 100644
--- a/sdk/azcore/etag.go
+++ b/sdk/azcore/etag.go
@@ -33,7 +33,7 @@ func (e ETag) Equals(right ETag, comparisonKind ComparisonType) bool {
 	}
 
 	if comparisonKind == Strong {
-		return !e.IsWeak() && right.IsWeak() && *e.value == *right.value
+		return !e.IsWeak() && !right.IsWeak() && *e.value == *right.value
 	}
 
 	leftStart := e.getStart()
diff --git a/sdk/azcore/etag_test.go b/sdk/azcore/etag_test.go
index e6953671fe5f..1767e461d41e 100644
--- a/sdk/azcore/etag_test.go
+++ b/sdk/azcore/etag_test.go
@@ -66,48 +66,51 @@ func TestETagWeak(t *testing.T) {
 	}
 }
 
-/*
-
-func TestEtagStars(t *testing.T) {
-	anyETag := ETagAny()
-	star := NewETag("*")
-	// weakStar := NewETag("W\"*\"")
-	quotedStar := NewETag("\"*\"")
-
-	strongETag := NewETag("\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
-
-	if anyETag.Equals(*anyETag, Strong) {
+func TestEtagEquality(t *testing.T) {
+	weakTag := NewETag("W/\"\"")
+	weakTag1 := NewETag("W/\"1\"")
+	weakTag2 := NewETag("W/\"Two\"")
+	strongTag1 := NewETag("\"1\"")
+	strongTag2 := NewETag("\"Two\"")
+	strongTagValidChars := NewETag("\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
+	weakTagValidChars := NewETag("W/\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
+
+	if weakTag.Equals(*weakTag, Strong) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+	if weakTag1.Equals(*weakTag1, Strong) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+	if weakTag2.Equals(*weakTag2, Strong) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+	if weakTagValidChars.Equals(*weakTagValidChars, Strong) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+	if !strongTag1.Equals(*strongTag1, Strong) {
 		t.Fatalf("Expected etags to be equal")
 	}
-	if anyETag.Equals(*ETagAny(), Strong) {
+	if !strongTag2.Equals(*strongTag2, Strong) {
 		t.Fatalf("Expected etags to be equal")
 	}
-	if anyETag.Equals(*strongETag, Strong) {
+	if !strongTagValidChars.Equals(*strongTagValidChars, Strong) {
 		t.Fatalf("Expected etags to be equal")
 	}
 
-	// expectEqual(t, star, star)
-	// expectEqual(t, star, ETagAny())
-	// expectEqual(t, star, anyETag)
-
-	// expectNotEqual(t, star, weakStar)
-	// expectNotEqual(t, weakStar, ETagAny())
-	// expectNotEqual(t, quotedStar, weakStar)
-
-	expectNotEqual(t, star, quotedStar)
-	expectEqual(t, anyETag, star)
-}
-*/
-
-func expectEqual(t *testing.T, left *ETag, right *ETag) {
-	if !left.Equals(*right, Strong) {
-		fmt.Println(*left.value, *right.value)
-		t.Fatalf("Expected etags to be equal")
+	if weakTag.Equals(*weakTag1, Strong) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+	if weakTagValidChars.Equals(*strongTagValidChars, Strong) {
+		t.Fatalf("Expected etags to not be equal")
 	}
-}
 
-func expectNotEqual(t *testing.T, left *ETag, right *ETag) {
-	if left.Equals(*right, Strong) {
+	if weakTag1.Equals(*weakTag2, Strong) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+	if weakTag1.Equals(*strongTag1, Strong) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+	if weakTag2.Equals(*strongTag2, Strong) {
 		t.Fatalf("Expected etags to not be equal")
 	}
 }

From 2f48548b0f934748d93a6443dbfe8da96da2fd80 Mon Sep 17 00:00:00 2001
From: seankane-msft <seankane@microsoft.com>
Date: Thu, 5 Aug 2021 15:58:22 -0400
Subject: [PATCH 05/13] weak tag comparisons

---
 sdk/azcore/etag.go      |   7 +--
 sdk/azcore/etag_test.go | 110 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 113 insertions(+), 4 deletions(-)

diff --git a/sdk/azcore/etag.go b/sdk/azcore/etag.go
index 61e978bd3e06..1a3e1003d60c 100644
--- a/sdk/azcore/etag.go
+++ b/sdk/azcore/etag.go
@@ -6,6 +6,7 @@
 package azcore
 
 import (
+	"fmt"
 	"strings"
 )
 
@@ -21,8 +22,8 @@ func NewETag(value string) *ETag {
 type ComparisonType string
 
 const (
-	Strong         ComparisonType = "strong"
-	WeakComparison ComparisonType = "weak"
+	Strong ComparisonType = "strong"
+	Weak   ComparisonType = "weak"
 )
 
 func (e ETag) Equals(right ETag, comparisonKind ComparisonType) bool {
@@ -40,7 +41,7 @@ func (e ETag) Equals(right ETag, comparisonKind ComparisonType) bool {
 	rightStart := right.getStart()
 
 	leftValue := (*e.value)[leftStart:]
-	rightValue := (*e.value)[rightStart:]
+	rightValue := (*right.value)[rightStart:]
 
 	return leftValue == rightValue
 }
diff --git a/sdk/azcore/etag_test.go b/sdk/azcore/etag_test.go
index 1767e461d41e..755184f6cc59 100644
--- a/sdk/azcore/etag_test.go
+++ b/sdk/azcore/etag_test.go
@@ -6,7 +6,6 @@
 package azcore
 
 import (
-	"fmt"
 	"testing"
 )
 
@@ -114,3 +113,112 @@ func TestEtagEquality(t *testing.T) {
 		t.Fatalf("Expected etags to not be equal")
 	}
 }
+
+func TestEtagAny(t *testing.T) {
+	anyETag := ETagAny()
+	star := NewETag("*")
+	weakStar := NewETag("W\"*\"")
+	quotedStart := NewETag("\"*\"")
+
+	if !anyETag.Equals(*anyETag, Strong) {
+		t.Fatalf("Expected etags to be equal")
+	}
+	if !anyETag.Equals(*ETagAny(), Strong) {
+		t.Fatalf("Expected etags to be equal")
+	}
+
+	if !star.Equals(*star, Strong) {
+		t.Fatalf("Expected etags to be equal")
+	}
+	if !star.Equals(*ETagAny(), Strong) {
+		t.Fatalf("Expected etags to be equal")
+	}
+	if !star.Equals(*anyETag, Strong) {
+		t.Fatalf("Expected etags to be equal")
+	}
+
+	if star.Equals(*weakStar, Strong) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+	if weakStar.Equals(*ETagAny(), Strong) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+	if quotedStart.Equals(*weakStar, Strong) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+
+
+	if star.Equals(*quotedStart, Strong) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+	if !ETagAny().Equals(*star, Strong) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+}
+
+func TestEtagWeakComparison(t *testing.T) {
+	// W/""
+	weakTag := NewETag("W/\"\"");
+	// W/"1"
+	weakTag1 := NewETag("W/\"1\"");
+	// W/"Two"
+	weakTagTwo := NewETag("W/\"Two\"");
+	// W/"two"
+	weakTagtwo := NewETag("W/\"two\"");
+	// "1"
+	strongTag1 := NewETag("\"1\"");
+	// "Two"
+	strongTagTwo := NewETag("\"Two\"");
+	// "two"
+	strongTagtwo := NewETag("\"two\"");
+
+	if !weakTag.Equals(*weakTag, Weak) {
+		t.Fatalf("Expected etags to be equal")
+	}
+	if !weakTag1.Equals(*weakTag1, Weak) {
+		t.Fatalf("Expected etags to be equal")
+	}
+	if !weakTagTwo.Equals(*weakTagTwo, Weak) {
+		t.Fatalf("Expected etags to be equal")
+	}
+	if !weakTagtwo.Equals(*weakTagtwo, Weak) {
+		t.Fatalf("Expected etags to be equal")
+	}
+	if !strongTag1.Equals(*strongTag1, Weak) {
+		t.Fatalf("Expected etags to be equal")
+	}
+	if !strongTagTwo.Equals(*strongTagTwo, Weak) {
+		t.Fatalf("Expected etags to be equal")
+	}
+	if !strongTagtwo.Equals(*strongTagtwo, Weak) {
+		t.Fatalf("Expected etags to be equal")
+	}
+
+	if weakTag.Equals(*weakTag1, Weak) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+	if weakTag1.Equals(*weakTagTwo, Weak) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+
+	if !weakTag1.Equals(*strongTag1, Weak) {
+		t.Fatalf("Expected etags to be equal")
+	}
+	if !weakTagTwo.Equals(*strongTagTwo, Weak) {
+		t.Fatalf("Expected etags to be equal")
+	}
+
+	if strongTagTwo.Equals(*weakTag1, Weak) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+	if strongTagTwo.Equals(*weakTagtwo, Weak) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+
+	if strongTagTwo.Equals(*strongTagtwo, Weak) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+	if weakTagTwo.Equals(*weakTagtwo, Weak) {
+		t.Fatalf("Expected etags to not be equal")
+	}
+}

From cbad20c209c65315a026b53df0eb65ab96e63473 Mon Sep 17 00:00:00 2001
From: seankane-msft <seankane@microsoft.com>
Date: Thu, 5 Aug 2021 16:07:08 -0400
Subject: [PATCH 06/13] adding docstrings

---
 sdk/azcore/etag.go      | 15 ++++++++++-----
 sdk/azcore/etag_test.go |  6 +++---
 2 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/sdk/azcore/etag.go b/sdk/azcore/etag.go
index 1a3e1003d60c..e6ff1de65da9 100644
--- a/sdk/azcore/etag.go
+++ b/sdk/azcore/etag.go
@@ -6,19 +6,21 @@
 package azcore
 
 import (
-	"fmt"
 	"strings"
 )
 
 // ETag is a property used for optimistic concurrency during updates
+// ETag is a validator based on https://tools.ietf.org/html/rfc7232#section-2.3.2
 type ETag struct {
 	value *string
 }
 
+// NewETag creates a new ETag struct
 func NewETag(value string) *ETag {
 	return &ETag{value: &value}
 }
 
+// ComparisonType specifies what type of comparison to use, Strong or Weak
 type ComparisonType string
 
 const (
@@ -26,6 +28,9 @@ const (
 	Weak   ComparisonType = "weak"
 )
 
+// Equals determines whether two entity-tags are equal. There are two types of comparison: Strong and Weak.
+// Strong comparison: two ETags are equivalent if both are not weak and their opaque-tags match character-by-character
+// Weak Comparison: two ETags are equivalent if their opaque-tags match character-by-character regardless of either or both being tagged as "weak"
 func (e ETag) Equals(right ETag, comparisonKind ComparisonType) bool {
 	// ETags are != if one value is null
 	if *e.value == "" || *right.value == "" {
@@ -53,22 +58,22 @@ func (e ETag) getStart() int {
 	return 0
 }
 
+// String returns a string representation of an ETag
 func (e ETag) String() string {
 	return *e.value
 }
 
+// HasValue returns whether an ETag is present
 func (e ETag) HasValue() bool {
 	return e.value != nil
 }
 
+// IsWeak specifies whether the ETag is strong or weak.
 func (e ETag) IsWeak() bool {
-	// fmt.Println(e.value != nil)
-	// fmt.Println(len(*e.value) >= 4)
-	// fmt.Println(strings.HasPrefix(*e.value, "W/\""))
-	// fmt.Println(strings.HasSuffix(*e.value, "\""))
 	return e.value != nil && len(*e.value) >= 4 && strings.HasPrefix(*e.value, "W/\"") && strings.HasSuffix(*e.value, "\"")
 }
 
+// ETagAny returns a new ETag that represents everything, the value is "*"
 func ETagAny() *ETag {
 	any := "*"
 	return &ETag{value: &any}
diff --git a/sdk/azcore/etag_test.go b/sdk/azcore/etag_test.go
index 755184f6cc59..bd4b9c986d22 100644
--- a/sdk/azcore/etag_test.go
+++ b/sdk/azcore/etag_test.go
@@ -40,12 +40,12 @@ func TestEtagEquals(t *testing.T) {
 
 func TestETagWeak(t *testing.T) {
 	et1 := NewETag("tag")
-	if !et1.IsWeak() {
+	if et1.IsWeak() {
 		t.Fatalf("Expected to be weak")
 	}
 
 	et2 := NewETag("\"tag\"")
-	if !et2.IsWeak() {
+	if et2.IsWeak() {
 		t.Fatalf("Expected to be weak")
 	}
 
@@ -60,7 +60,7 @@ func TestETagWeak(t *testing.T) {
 	}
 
 	et5 := ETagAny()
-	if !et5.IsWeak() {
+	if et5.IsWeak() {
 		t.Fatalf("Expected to be weak")
 	}
 }

From 24803fd8ae9b761f7e549f46881c8557bc0e2c4e Mon Sep 17 00:00:00 2001
From: seankane-msft <seankane@microsoft.com>
Date: Fri, 6 Aug 2021 12:19:50 -0400
Subject: [PATCH 07/13] addressing richard and jeffs feedback. split equals to
 strong and weak, using more HasValue throughout

---
 sdk/azcore/etag.go      |  77 ++++-------
 sdk/azcore/etag_test.go | 293 ++++++++++++++--------------------------
 sdk/azcore/go.mod       |   1 +
 sdk/azcore/go.sum       |   4 +
 4 files changed, 135 insertions(+), 240 deletions(-)

diff --git a/sdk/azcore/etag.go b/sdk/azcore/etag.go
index e6ff1de65da9..92b3afc22b57 100644
--- a/sdk/azcore/etag.go
+++ b/sdk/azcore/etag.go
@@ -11,70 +11,51 @@ import (
 
 // ETag is a property used for optimistic concurrency during updates
 // ETag is a validator based on https://tools.ietf.org/html/rfc7232#section-2.3.2
-type ETag struct {
-	value *string
-}
+type ETag *string
 
-// NewETag creates a new ETag struct
-func NewETag(value string) *ETag {
-	return &ETag{value: &value}
+// StrongEquals does a strong comparison of two ETags. StrongEquals returns true when both
+// ETags are not weak and the values of the underlying strings are equal. If both ETags are "nil" they are considered equal
+func StrongEquals(a, b ETag) bool {
+	if !HasValue(a) || !HasValue(b) {
+		return a == b
+	}
+	return !IsWeak(a) && !IsWeak(b) && *a == *b
 }
 
-// ComparisonType specifies what type of comparison to use, Strong or Weak
-type ComparisonType string
-
-const (
-	Strong ComparisonType = "strong"
-	Weak   ComparisonType = "weak"
-)
-
-// Equals determines whether two entity-tags are equal. There are two types of comparison: Strong and Weak.
-// Strong comparison: two ETags are equivalent if both are not weak and their opaque-tags match character-by-character
-// Weak Comparison: two ETags are equivalent if their opaque-tags match character-by-character regardless of either or both being tagged as "weak"
-func (e ETag) Equals(right ETag, comparisonKind ComparisonType) bool {
-	// ETags are != if one value is null
-	if *e.value == "" || *right.value == "" {
-		// If both are null, they are considered equal
-		return *e.value == *right.value
+// WeakEquals does a weak compariosn of two ETags. Two ETags are equivalent if their opaque-tags match
+// character-by-character, regardless of either or both being tagged as "weak". If both ETags are "nil" they are considered equal
+func WeakEquals(a, b ETag) bool {
+	if !HasValue(a) || !HasValue(b) {
+		return a == b
 	}
 
-	if comparisonKind == Strong {
-		return !e.IsWeak() && !right.IsWeak() && *e.value == *right.value
+	getStart := func(e ETag) int {
+		if IsWeak(e) {
+			return 2
+		}
+		return 0
 	}
+	aStart := getStart(a)
+	bStart := getStart(b)
 
-	leftStart := e.getStart()
-	rightStart := right.getStart()
-
-	leftValue := (*e.value)[leftStart:]
-	rightValue := (*right.value)[rightStart:]
-
-	return leftValue == rightValue
-}
-
-func (e ETag) getStart() int {
-	if e.IsWeak() {
-		return 2
-	}
-	return 0
-}
+	aVal := (*a)[aStart:]
+	bVal := (*b)[bStart:]
 
-// String returns a string representation of an ETag
-func (e ETag) String() string {
-	return *e.value
+	return aVal == bVal
 }
 
 // HasValue returns whether an ETag is present
-func (e ETag) HasValue() bool {
-	return e.value != nil
+func HasValue(e ETag) bool {
+	return e != nil
 }
 
 // IsWeak specifies whether the ETag is strong or weak.
-func (e ETag) IsWeak() bool {
-	return e.value != nil && len(*e.value) >= 4 && strings.HasPrefix(*e.value, "W/\"") && strings.HasSuffix(*e.value, "\"")
+func IsWeak(e ETag) bool {
+	return HasValue(e) && len(*e) >= 4 && strings.HasPrefix(*e, "W/\"") && strings.HasSuffix(*e, "\"")
 }
 
 // ETagAny returns a new ETag that represents everything, the value is "*"
-func ETagAny() *ETag {
+func ETagAny() ETag {
 	any := "*"
-	return &ETag{value: &any}
+	return ETag(&any)
 }
diff --git a/sdk/azcore/etag_test.go b/sdk/azcore/etag_test.go
index bd4b9c986d22..c71880dc4167 100644
--- a/sdk/azcore/etag_test.go
+++ b/sdk/azcore/etag_test.go
@@ -7,218 +7,127 @@ package azcore
 
 import (
 	"testing"
+
+	"github.com/stretchr/testify/require"
 )
 
-func TestEtagEquals(t *testing.T) {
-	e1 := NewETag("tag")
-	if e1.String() != "tag" {
-		t.Fatalf("ETag values are not equal")
-	}
-
-	e2 := NewETag("\"tag\"")
-	if e2.String() != "\"tag\"" {
-		t.Fatalf("ETag values are not equal")
-	}
-
-	e3 := NewETag("W/\"weakETag\"")
-	if e3.String() != "W/\"weakETag\"" {
-		t.Fatalf("ETag values are not equal")
-	}
-	if !e3.IsWeak() {
-		t.Fatalf("ETag is expected to be weak")
-	}
-
-	strongETag := NewETag("\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
-	if strongETag.String() != "\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"" {
-		t.Fatalf("Etag values are not equal")
-	}
-
-	if ETagAny().IsWeak() {
-		t.Fatalf("ETagAny should not be weak")
-	}
+func createETag(s string) ETag {
+	return ETag(&s)
+}
+
+func TestETagEquals(t *testing.T) {
+	e1 := createETag("tag")
+	require.Equal(t, *e1, "tag")
+
+	e2 := createETag("\"tag\"")
+	require.Equal(t, *e2, "\"tag\"")
+
+	e3 := createETag("W/\"weakETag\"")
+	require.Equal(t, *e3, "W/\"weakETag\"")
+	require.Truef(t, IsWeak(e3), "ETag is ecpected to be weak")
+
+	strongETag := createETag("\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
+	require.Equal(t, *strongETag, "\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
+
+	require.Falsef(t, IsWeak(ETagAny()), "ETagAny should not be weak")
 }
 
 func TestETagWeak(t *testing.T) {
-	et1 := NewETag("tag")
-	if et1.IsWeak() {
-		t.Fatalf("Expected to be weak")
-	}
-
-	et2 := NewETag("\"tag\"")
-	if et2.IsWeak() {
-		t.Fatalf("Expected to be weak")
-	}
-
-	et3 := NewETag("W/\"weakETag\"")
-	if !et3.IsWeak() {
-		t.Fatalf("Expected to be weak")
-	}
-
-	et4 := NewETag("W/\"\"")
-	if !et4.IsWeak() {
-		t.Fatalf("Expected to be weak")
-	}
+	et1 := createETag("tag")
+	require.Falsef(t, IsWeak(et1), "expected etag to be strong")
+
+	et2 := createETag("\"tag\"")
+	require.Falsef(t, IsWeak(et2), "expected etag to be strong")
+
+	et3 := createETag("W/\"weakETag\"")
+	require.Truef(t, IsWeak(et3), "expected etag to be weak")
+
+	et4 := createETag("W/\"\"")
+	require.Truef(t, IsWeak(et4), "expected etag to be weak")
 
 	et5 := ETagAny()
-	if et5.IsWeak() {
-		t.Fatalf("Expected to be weak")
-	}
+	require.Falsef(t, IsWeak(et5), "expected etag to be strong")
 }
 
-func TestEtagEquality(t *testing.T) {
-	weakTag := NewETag("W/\"\"")
-	weakTag1 := NewETag("W/\"1\"")
-	weakTag2 := NewETag("W/\"Two\"")
-	strongTag1 := NewETag("\"1\"")
-	strongTag2 := NewETag("\"Two\"")
-	strongTagValidChars := NewETag("\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
-	weakTagValidChars := NewETag("W/\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
-
-	if weakTag.Equals(*weakTag, Strong) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-	if weakTag1.Equals(*weakTag1, Strong) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-	if weakTag2.Equals(*weakTag2, Strong) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-	if weakTagValidChars.Equals(*weakTagValidChars, Strong) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-	if !strongTag1.Equals(*strongTag1, Strong) {
-		t.Fatalf("Expected etags to be equal")
-	}
-	if !strongTag2.Equals(*strongTag2, Strong) {
-		t.Fatalf("Expected etags to be equal")
-	}
-	if !strongTagValidChars.Equals(*strongTagValidChars, Strong) {
-		t.Fatalf("Expected etags to be equal")
-	}
-
-	if weakTag.Equals(*weakTag1, Strong) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-	if weakTagValidChars.Equals(*strongTagValidChars, Strong) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-
-	if weakTag1.Equals(*weakTag2, Strong) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-	if weakTag1.Equals(*strongTag1, Strong) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-	if weakTag2.Equals(*strongTag2, Strong) {
-		t.Fatalf("Expected etags to not be equal")
-	}
+func TestETagEquality(t *testing.T) {
+	weakTag := createETag("W/\"\"")
+	weakTag1 := createETag("W/\"1\"")
+	weakTag2 := createETag("W/\"Two\"")
+	strongTag1 := createETag("\"1\"")
+	strongTag2 := createETag("\"Two\"")
+	strongTagValidChars := createETag("\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
+	weakTagValidChars := createETag("W/\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
+
+	require.Falsef(t, StrongEquals(weakTag, weakTag), "Expected etags to not be equal")
+	require.Falsef(t, StrongEquals(weakTag1, weakTag1), "Expected etags to not be equal")
+	require.Falsef(t, StrongEquals(weakTag2, weakTag2), "Expected etags to not be equal")
+	require.Falsef(t, StrongEquals(weakTagValidChars, weakTagValidChars), "Expected etags to not be equal")
+
+	require.Truef(t, StrongEquals(strongTag1, strongTag1), "Expected etags to be equal")
+	require.Truef(t, StrongEquals(strongTag2, strongTag2), "Expected etags to be equal")
+	require.Truef(t, StrongEquals(strongTagValidChars, strongTagValidChars), "Expected etags to be equal")
+
+	require.Falsef(t, StrongEquals(weakTag, weakTag1), "Expected etags to not be equal")
+	require.Falsef(t, StrongEquals(weakTagValidChars, strongTagValidChars), "Expected etags to not be equal")
+	require.Falsef(t, StrongEquals(weakTag1, weakTag2), "Expected etags to not be equal")
+	require.Falsef(t, StrongEquals(weakTag1, strongTag1), "Expected etags to not be equal")
+	require.Falsef(t, StrongEquals(weakTag2, strongTag2), "Expected etags to not be equal")
 }
 
 func TestEtagAny(t *testing.T) {
 	anyETag := ETagAny()
-	star := NewETag("*")
-	weakStar := NewETag("W\"*\"")
-	quotedStart := NewETag("\"*\"")
-
-	if !anyETag.Equals(*anyETag, Strong) {
-		t.Fatalf("Expected etags to be equal")
-	}
-	if !anyETag.Equals(*ETagAny(), Strong) {
-		t.Fatalf("Expected etags to be equal")
-	}
-
-	if !star.Equals(*star, Strong) {
-		t.Fatalf("Expected etags to be equal")
-	}
-	if !star.Equals(*ETagAny(), Strong) {
-		t.Fatalf("Expected etags to be equal")
-	}
-	if !star.Equals(*anyETag, Strong) {
-		t.Fatalf("Expected etags to be equal")
-	}
-
-	if star.Equals(*weakStar, Strong) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-	if weakStar.Equals(*ETagAny(), Strong) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-	if quotedStart.Equals(*weakStar, Strong) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-
-
-	if star.Equals(*quotedStart, Strong) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-	if !ETagAny().Equals(*star, Strong) {
-		t.Fatalf("Expected etags to not be equal")
-	}
+	star := createETag("*")
+	weakStar := createETag("W\"*\"")
+	quotedStart := createETag("\"*\"")
+
+	require.Truef(t, StrongEquals(anyETag, anyETag), "Expected etags to be equal")
+	require.Truef(t, StrongEquals(anyETag, ETagAny()), "Expected etags to be equal")
+
+	require.Truef(t, StrongEquals(star, star), "Expected etags to be equal")
+	require.Truef(t, StrongEquals(star, ETagAny()), "Expected etags to be equal")
+	require.Truef(t, StrongEquals(star, anyETag), "Expected etags to be equal")
+
+	require.Falsef(t, StrongEquals(weakStar, star), "Expected etags to be equal")
+	require.Falsef(t, StrongEquals(weakStar, ETagAny()), "Expected etags to be equal")
+	require.Falsef(t, StrongEquals(quotedStart, weakStar), "Expected etags to be equal")
+
+	require.Falsef(t, StrongEquals(star, quotedStart), "Expected etags to be equal")
+	require.Falsef(t, StrongEquals(ETagAny(), star), "Expected etags to be equal")
 }
 
-func TestEtagWeakComparison(t *testing.T) {
+func TestETagWeakComparison(t *testing.T) {
 	// W/""
-	weakTag := NewETag("W/\"\"");
+	weakTag := createETag("W/\"\"")
 	// W/"1"
-	weakTag1 := NewETag("W/\"1\"");
+	weakTag1 := createETag("W/\"1\"")
 	// W/"Two"
-	weakTagTwo := NewETag("W/\"Two\"");
+	weakTagTwo := createETag("W/\"Two\"")
 	// W/"two"
-	weakTagtwo := NewETag("W/\"two\"");
+	weakTagtwo := createETag("W/\"two\"")
 	// "1"
-	strongTag1 := NewETag("\"1\"");
+	strongTag1 := createETag("\"1\"")
 	// "Two"
-	strongTagTwo := NewETag("\"Two\"");
+	strongTagTwo := createETag("\"Two\"")
 	// "two"
-	strongTagtwo := NewETag("\"two\"");
-
-	if !weakTag.Equals(*weakTag, Weak) {
-		t.Fatalf("Expected etags to be equal")
-	}
-	if !weakTag1.Equals(*weakTag1, Weak) {
-		t.Fatalf("Expected etags to be equal")
-	}
-	if !weakTagTwo.Equals(*weakTagTwo, Weak) {
-		t.Fatalf("Expected etags to be equal")
-	}
-	if !weakTagtwo.Equals(*weakTagtwo, Weak) {
-		t.Fatalf("Expected etags to be equal")
-	}
-	if !strongTag1.Equals(*strongTag1, Weak) {
-		t.Fatalf("Expected etags to be equal")
-	}
-	if !strongTagTwo.Equals(*strongTagTwo, Weak) {
-		t.Fatalf("Expected etags to be equal")
-	}
-	if !strongTagtwo.Equals(*strongTagtwo, Weak) {
-		t.Fatalf("Expected etags to be equal")
-	}
-
-	if weakTag.Equals(*weakTag1, Weak) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-	if weakTag1.Equals(*weakTagTwo, Weak) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-
-	if !weakTag1.Equals(*strongTag1, Weak) {
-		t.Fatalf("Expected etags to be equal")
-	}
-	if !weakTagTwo.Equals(*strongTagTwo, Weak) {
-		t.Fatalf("Expected etags to be equal")
-	}
-
-	if strongTagTwo.Equals(*weakTag1, Weak) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-	if strongTagTwo.Equals(*weakTagtwo, Weak) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-
-	if strongTagTwo.Equals(*strongTagtwo, Weak) {
-		t.Fatalf("Expected etags to not be equal")
-	}
-	if weakTagTwo.Equals(*weakTagtwo, Weak) {
-		t.Fatalf("Expected etags to not be equal")
-	}
+	strongTagtwo := createETag("\"two\"")
+
+	require.Truef(t, WeakEquals(weakTag, weakTag), "expected etags to be equal")
+	require.Truef(t, WeakEquals(weakTag1, weakTag1), "expected etags to be equal")
+	require.Truef(t, WeakEquals(weakTagTwo, weakTagTwo), "expected etags to be equal")
+	require.Truef(t, WeakEquals(weakTagtwo, weakTagtwo), "expected etags to be equal")
+	require.Truef(t, WeakEquals(strongTag1, strongTag1), "expected etags to be equal")
+	require.Truef(t, WeakEquals(strongTagTwo, strongTagTwo), "expected etags to be equal")
+	require.Truef(t, WeakEquals(strongTagtwo, strongTagtwo), "expected etags to be equal")
+
+	require.Falsef(t, WeakEquals(weakTag, weakTag1), "Expected etags to not be equal")
+	require.Falsef(t, WeakEquals(weakTag1, weakTagTwo), "Expected etags to not be equal")
+
+	require.Truef(t, WeakEquals(weakTag1, strongTag1), "expected etags to be equal")
+	require.Truef(t, WeakEquals(weakTagTwo, strongTagTwo), "expected etags to be equal")
+
+	require.Falsef(t, WeakEquals(strongTagTwo, weakTag1), "Expected etags to not be equal")
+	require.Falsef(t, WeakEquals(strongTagTwo, weakTagtwo), "Expected etags to not be equal")
+
+	require.Falsef(t, WeakEquals(strongTagTwo, strongTagtwo), "Expected etags to not be equal")
+	require.Falsef(t, WeakEquals(weakTagTwo, weakTagtwo), "Expected etags to not be equal")
 }
diff --git a/sdk/azcore/go.mod b/sdk/azcore/go.mod
index db8caa57b4fe..d1352741ce9c 100644
--- a/sdk/azcore/go.mod
+++ b/sdk/azcore/go.mod
@@ -2,6 +2,7 @@ module github.com/Azure/azure-sdk-for-go/sdk/azcore
 
 require (
 	github.com/Azure/azure-sdk-for-go/sdk/internal v0.5.2
+	github.com/stretchr/testify v1.7.0 // indirect
 	golang.org/x/net v0.0.0-20210610132358-84b48f89b13b
 )
 
diff --git a/sdk/azcore/go.sum b/sdk/azcore/go.sum
index 62d184faa625..3d9a653b9fb7 100644
--- a/sdk/azcore/go.sum
+++ b/sdk/azcore/go.sum
@@ -1,11 +1,14 @@
 github.com/Azure/azure-sdk-for-go/sdk/internal v0.5.2 h1:E2xwjsWU81O/XuSaxAGa8Jmqz4Vm4NmrpMSO9/XevDg=
 github.com/Azure/azure-sdk-for-go/sdk/internal v0.5.2/go.mod h1:Hl9Vte0DDolj9zqzmfnmY9/zfZbiT5KnvXqVwAvnR8Q=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dnaeon/go-vcr v1.2.0/go.mod h1:R4UdLID7HZT3taECzJs4YgbbH6PIGXB6W/sc5OLb6RQ=
 github.com/modocache/gover v0.0.0-20171022184752-b58185e213c5/go.mod h1:caMODM3PzxT8aQXRPkAt8xlV/e7d7w8GM5g0fa5F0D8=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 golang.org/x/net v0.0.0-20210610132358-84b48f89b13b h1:k+E048sYJHyVnsr1GDrRZWQ32D2C7lWs9JRc0bel53A=
 golang.org/x/net v0.0.0-20210610132358-84b48f89b13b/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
@@ -19,4 +22,5 @@ gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8
 gopkg.in/yaml.v2 v2.2.8/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
 gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

From ea86e53529aee951c23abd574f29fb53dff7b197 Mon Sep 17 00:00:00 2001
From: seankane-msft <seankane@microsoft.com>
Date: Fri, 6 Aug 2021 12:26:32 -0400
Subject: [PATCH 08/13] fixing one test

---
 sdk/azcore/etag_test.go | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sdk/azcore/etag_test.go b/sdk/azcore/etag_test.go
index c71880dc4167..be8cec923b0c 100644
--- a/sdk/azcore/etag_test.go
+++ b/sdk/azcore/etag_test.go
@@ -92,7 +92,8 @@ func TestEtagAny(t *testing.T) {
 	require.Falsef(t, StrongEquals(quotedStart, weakStar), "Expected etags to be equal")
 
 	require.Falsef(t, StrongEquals(star, quotedStart), "Expected etags to be equal")
-	require.Falsef(t, StrongEquals(ETagAny(), star), "Expected etags to be equal")
+
+	require.Truef(t, StrongEquals(ETagAny(), star), "Expected etags to be equal")
 }
 
 func TestETagWeakComparison(t *testing.T) {

From 72f49ccc2034f66baef3bbcedc0c29489c4a43b6 Mon Sep 17 00:00:00 2001
From: seankane-msft <seankane@microsoft.com>
Date: Fri, 6 Aug 2021 12:59:13 -0400
Subject: [PATCH 09/13] adding EOL

---
 sdk/azcore/core.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sdk/azcore/core.go b/sdk/azcore/core.go
index 1219c5f419c8..ff915e59eae3 100644
--- a/sdk/azcore/core.go
+++ b/sdk/azcore/core.go
@@ -202,4 +202,4 @@ func IsNullValue(v interface{}) bool {
 	}
 	// no sentinel object for this *t
 	return false
-}
\ No newline at end of file
+}

From 76d5720eac8673c5a012f666cc0a47a9b1bbdda3 Mon Sep 17 00:00:00 2001
From: seankane-msft <seankane@microsoft.com>
Date: Fri, 6 Aug 2021 13:23:03 -0400
Subject: [PATCH 10/13] adding note about the difference between nil and empty
 etags

---
 sdk/azcore/etag.go | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sdk/azcore/etag.go b/sdk/azcore/etag.go
index 92b3afc22b57..f3865ba43902 100644
--- a/sdk/azcore/etag.go
+++ b/sdk/azcore/etag.go
@@ -11,6 +11,7 @@ import (
 
 // ETag is a property used for optimistic concurrency during updates
 // ETag is a validator based on https://tools.ietf.org/html/rfc7232#section-2.3.2
+// An ETag can be empty ("") or nil. A nil etag represents the absence of an ETag, while an empty ETag is a valid ETag (e.g. https://www.rfc-editor.org/rfc/rfc7232.html#section-2.3)
 type ETag *string
 
 // StrongEquals does a strong comparison of two ETags. StrongEquals returns true when both

From cd5fe796693af88d0e223382c81df6f1fa049571 Mon Sep 17 00:00:00 2001
From: seankane-msft <seankane@microsoft.com>
Date: Fri, 6 Aug 2021 17:30:42 -0400
Subject: [PATCH 11/13] more feedback

---
 sdk/azcore/etag.go      |  49 +++++++------------
 sdk/azcore/etag_test.go | 104 ++++++++++++++++++++--------------------
 2 files changed, 69 insertions(+), 84 deletions(-)

diff --git a/sdk/azcore/etag.go b/sdk/azcore/etag.go
index f3865ba43902..ad9306fe7a59 100644
--- a/sdk/azcore/etag.go
+++ b/sdk/azcore/etag.go
@@ -11,52 +11,37 @@ import (
 
 // ETag is a property used for optimistic concurrency during updates
 // ETag is a validator based on https://tools.ietf.org/html/rfc7232#section-2.3.2
-// An ETag can be empty ("") or nil. A nil etag represents the absence of an ETag, while an empty ETag is a valid ETag (e.g. https://www.rfc-editor.org/rfc/rfc7232.html#section-2.3)
-type ETag *string
+// An ETag can be empty ("").
+type ETag string
 
-// StrongEquals does a strong comparison of two ETags. StrongEquals returns true when both
+// ETagAny is an ETag that represents everything, the value is "*"
+const ETagAny ETag = "*"
+
+// Equals does a strong comparison of two ETags. Equals returns true when both
 // ETags are not weak and the values of the underlying strings are equal. If both ETags are "nil" they are considered equal
-func StrongEquals(a, b ETag) bool {
-	if !HasValue(a) || !HasValue(b) {
-		return a == b
-	}
-	return !IsWeak(a) && !IsWeak(b) && *a == *b
+func (e ETag) Equals(other ETag) bool {
+	return !e.IsWeak() && !other.IsWeak() && e == other
 }
 
 // WeakEquals does a weak compariosn of two ETags. Two ETags are equivalent if their opaque-tags match
 // character-by-character, regardless of either or both being tagged as "weak". If both ETags are "nil" they are considered equal
-func WeakEquals(a, b ETag) bool {
-	if !HasValue(a) || !HasValue(b) {
-		return a == b
-	}
-
-	getStart := func(e ETag) int {
-		if IsWeak(e) {
+func (e ETag) WeakEquals(other ETag) bool {
+	getStart := func(e1 ETag) int {
+		if e1.IsWeak() {
 			return 2
 		}
 		return 0
 	}
-	aStart := getStart(a)
-	bStart := getStart(b)
+	aStart := getStart(e)
+	bStart := getStart(other)
 
-	aVal := (*a)[aStart:]
-	bVal := (*b)[bStart:]
+	aVal := e[aStart:]
+	bVal := other[bStart:]
 
 	return aVal == bVal
 }
 
-// HasValue returns whether an ETag is present
-func HasValue(e ETag) bool {
-	return e != nil
-}
-
 // IsWeak specifies whether the ETag is strong or weak.
-func IsWeak(e ETag) bool {
-	return HasValue(e) && len(*e) >= 4 && strings.HasPrefix(*e, "W/\"") && strings.HasSuffix(*e, "\"")
-}
-
-// ETagAny returns a new ETag that represents everything, the value is "*"
-func ETagAny() ETag {
-	any := "*"
-	return ETag(&any)
+func (e ETag) IsWeak() bool {
+	return len(e) >= 4 && strings.HasPrefix(string(e), "W/\"") && strings.HasSuffix(string(e), "\"")
 }
diff --git a/sdk/azcore/etag_test.go b/sdk/azcore/etag_test.go
index be8cec923b0c..7cbd03fe6edd 100644
--- a/sdk/azcore/etag_test.go
+++ b/sdk/azcore/etag_test.go
@@ -12,41 +12,41 @@ import (
 )
 
 func createETag(s string) ETag {
-	return ETag(&s)
+	return ETag(s)
 }
 
 func TestETagEquals(t *testing.T) {
 	e1 := createETag("tag")
-	require.Equal(t, *e1, "tag")
+	require.Equal(t, string(e1), "tag")
 
 	e2 := createETag("\"tag\"")
-	require.Equal(t, *e2, "\"tag\"")
+	require.Equal(t, string(e2), "\"tag\"")
 
 	e3 := createETag("W/\"weakETag\"")
-	require.Equal(t, *e3, "W/\"weakETag\"")
-	require.Truef(t, IsWeak(e3), "ETag is ecpected to be weak")
+	require.Equal(t, string(e3), "W/\"weakETag\"")
+	require.Truef(t, e3.IsWeak(), "ETag is expected to be weak")
 
 	strongETag := createETag("\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
-	require.Equal(t, *strongETag, "\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
+	require.Equal(t, string(strongETag), "\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
 
-	require.Falsef(t, IsWeak(ETagAny()), "ETagAny should not be weak")
+	require.Falsef(t, ETagAny.IsWeak(), "ETagAny should not be weak")
 }
 
 func TestETagWeak(t *testing.T) {
 	et1 := createETag("tag")
-	require.Falsef(t, IsWeak(et1), "expected etag to be strong")
+	require.Falsef(t, et1.IsWeak(), "expected etag to be strong")
 
 	et2 := createETag("\"tag\"")
-	require.Falsef(t, IsWeak(et2), "expected etag to be strong")
+	require.Falsef(t, et2.IsWeak(), "expected etag to be strong")
 
 	et3 := createETag("W/\"weakETag\"")
-	require.Truef(t, IsWeak(et3), "expected etag to be weak")
+	require.Truef(t, et3.IsWeak(), "expected etag to be weak")
 
 	et4 := createETag("W/\"\"")
-	require.Truef(t, IsWeak(et4), "expected etag to be weak")
+	require.Truef(t, et4.IsWeak(), "expected etag to be weak")
 
-	et5 := ETagAny()
-	require.Falsef(t, IsWeak(et5), "expected etag to be strong")
+	et5 := ETagAny
+	require.Falsef(t, et5.IsWeak(), "expected etag to be strong")
 }
 
 func TestETagEquality(t *testing.T) {
@@ -58,42 +58,42 @@ func TestETagEquality(t *testing.T) {
 	strongTagValidChars := createETag("\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
 	weakTagValidChars := createETag("W/\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
 
-	require.Falsef(t, StrongEquals(weakTag, weakTag), "Expected etags to not be equal")
-	require.Falsef(t, StrongEquals(weakTag1, weakTag1), "Expected etags to not be equal")
-	require.Falsef(t, StrongEquals(weakTag2, weakTag2), "Expected etags to not be equal")
-	require.Falsef(t, StrongEquals(weakTagValidChars, weakTagValidChars), "Expected etags to not be equal")
+	require.Falsef(t, weakTag.Equals(weakTag), "Expected etags to not be equal")
+	require.Falsef(t, weakTag1.Equals( weakTag1), "Expected etags to not be equal")
+	require.Falsef(t, weakTag2.Equals(weakTag2), "Expected etags to not be equal")
+	require.Falsef(t, weakTagValidChars.Equals(weakTagValidChars), "Expected etags to not be equal")
 
-	require.Truef(t, StrongEquals(strongTag1, strongTag1), "Expected etags to be equal")
-	require.Truef(t, StrongEquals(strongTag2, strongTag2), "Expected etags to be equal")
-	require.Truef(t, StrongEquals(strongTagValidChars, strongTagValidChars), "Expected etags to be equal")
+	require.Truef(t, strongTag1.Equals(strongTag1), "Expected etags to be equal")
+	require.Truef(t, strongTag2.Equals(strongTag2), "Expected etags to be equal")
+	require.Truef(t, strongTagValidChars.Equals(strongTagValidChars), "Expected etags to be equal")
 
-	require.Falsef(t, StrongEquals(weakTag, weakTag1), "Expected etags to not be equal")
-	require.Falsef(t, StrongEquals(weakTagValidChars, strongTagValidChars), "Expected etags to not be equal")
-	require.Falsef(t, StrongEquals(weakTag1, weakTag2), "Expected etags to not be equal")
-	require.Falsef(t, StrongEquals(weakTag1, strongTag1), "Expected etags to not be equal")
-	require.Falsef(t, StrongEquals(weakTag2, strongTag2), "Expected etags to not be equal")
+	require.Falsef(t, weakTag1.Equals(weakTag), "Expected etags to not be equal")
+	require.Falsef(t, strongTagValidChars.Equals(weakTagValidChars), "Expected etags to not be equal")
+	require.Falsef(t, weakTag2.Equals(weakTag1), "Expected etags to not be equal")
+	require.Falsef(t, strongTag1.Equals(weakTag1), "Expected etags to not be equal")
+	require.Falsef(t, strongTag2.Equals(weakTag2), "Expected etags to not be equal")
 }
 
 func TestEtagAny(t *testing.T) {
-	anyETag := ETagAny()
+	anyETag := ETagAny
 	star := createETag("*")
 	weakStar := createETag("W\"*\"")
-	quotedStart := createETag("\"*\"")
+	quotedStar := createETag("\"*\"")
 
-	require.Truef(t, StrongEquals(anyETag, anyETag), "Expected etags to be equal")
-	require.Truef(t, StrongEquals(anyETag, ETagAny()), "Expected etags to be equal")
+	require.Truef(t, anyETag.Equals(anyETag), "Expected etags to be equal")
+	require.Truef(t, ETagAny.Equals(anyETag), "Expected etags to be equal")
 
-	require.Truef(t, StrongEquals(star, star), "Expected etags to be equal")
-	require.Truef(t, StrongEquals(star, ETagAny()), "Expected etags to be equal")
-	require.Truef(t, StrongEquals(star, anyETag), "Expected etags to be equal")
+	require.Truef(t, star.Equals(star), "Expected etags to be equal")
+	require.Truef(t, ETagAny.Equals(star), "Expected etags to be equal")
+	require.Truef(t, anyETag.Equals(star), "Expected etags to be equal")
 
-	require.Falsef(t, StrongEquals(weakStar, star), "Expected etags to be equal")
-	require.Falsef(t, StrongEquals(weakStar, ETagAny()), "Expected etags to be equal")
-	require.Falsef(t, StrongEquals(quotedStart, weakStar), "Expected etags to be equal")
+	require.Falsef(t, star.Equals(weakStar), "Expected etags to be equal")
+	require.Falsef(t, ETagAny.Equals(weakStar), "Expected etags to be equal")
+	require.Falsef(t, weakStar.Equals(quotedStar), "Expected etags to be equal")
 
-	require.Falsef(t, StrongEquals(star, quotedStart), "Expected etags to be equal")
+	require.Falsef(t, quotedStar.Equals(star), "Expected etags to be equal")
 
-	require.Truef(t, StrongEquals(ETagAny(), star), "Expected etags to be equal")
+	require.Truef(t, star.Equals(ETagAny), "Expected etags to be equal")
 }
 
 func TestETagWeakComparison(t *testing.T) {
@@ -112,23 +112,23 @@ func TestETagWeakComparison(t *testing.T) {
 	// "two"
 	strongTagtwo := createETag("\"two\"")
 
-	require.Truef(t, WeakEquals(weakTag, weakTag), "expected etags to be equal")
-	require.Truef(t, WeakEquals(weakTag1, weakTag1), "expected etags to be equal")
-	require.Truef(t, WeakEquals(weakTagTwo, weakTagTwo), "expected etags to be equal")
-	require.Truef(t, WeakEquals(weakTagtwo, weakTagtwo), "expected etags to be equal")
-	require.Truef(t, WeakEquals(strongTag1, strongTag1), "expected etags to be equal")
-	require.Truef(t, WeakEquals(strongTagTwo, strongTagTwo), "expected etags to be equal")
-	require.Truef(t, WeakEquals(strongTagtwo, strongTagtwo), "expected etags to be equal")
+	require.Truef(t, weakTag.WeakEquals(weakTag), "expected etags to be equal")
+	require.Truef(t, weakTag1.WeakEquals(weakTag1), "expected etags to be equal")
+	require.Truef(t, weakTagTwo.WeakEquals(weakTagTwo), "expected etags to be equal")
+	require.Truef(t, weakTagtwo.WeakEquals(weakTagtwo), "expected etags to be equal")
+	require.Truef(t, strongTag1.WeakEquals(strongTag1), "expected etags to be equal")
+	require.Truef(t, strongTagTwo.WeakEquals(strongTagTwo), "expected etags to be equal")
+	require.Truef(t, strongTagtwo.WeakEquals(strongTagtwo), "expected etags to be equal")
 
-	require.Falsef(t, WeakEquals(weakTag, weakTag1), "Expected etags to not be equal")
-	require.Falsef(t, WeakEquals(weakTag1, weakTagTwo), "Expected etags to not be equal")
+	require.Falsef(t, weakTag1.WeakEquals(weakTag), "Expected etags to not be equal")
+	require.Falsef(t, weakTagTwo.WeakEquals(weakTag1), "Expected etags to not be equal")
 
-	require.Truef(t, WeakEquals(weakTag1, strongTag1), "expected etags to be equal")
-	require.Truef(t, WeakEquals(weakTagTwo, strongTagTwo), "expected etags to be equal")
+	require.Truef(t, strongTag1.WeakEquals(weakTag1), "expected etags to be equal")
+	require.Truef(t, strongTagTwo.WeakEquals(weakTagTwo), "expected etags to be equal")
 
-	require.Falsef(t, WeakEquals(strongTagTwo, weakTag1), "Expected etags to not be equal")
-	require.Falsef(t, WeakEquals(strongTagTwo, weakTagtwo), "Expected etags to not be equal")
+	require.Falsef(t, weakTag1.WeakEquals(strongTagTwo), "Expected etags to not be equal")
+	require.Falsef(t, weakTagtwo.WeakEquals(strongTagTwo), "Expected etags to not be equal")
 
-	require.Falsef(t, WeakEquals(strongTagTwo, strongTagtwo), "Expected etags to not be equal")
-	require.Falsef(t, WeakEquals(weakTagTwo, weakTagtwo), "Expected etags to not be equal")
+	require.Falsef(t, strongTagtwo.WeakEquals(strongTagTwo), "Expected etags to not be equal")
+	require.Falsef(t, weakTagtwo.WeakEquals(weakTagTwo), "Expected etags to not be equal")
 }

From c6a099d1aa83778bdc677a707bc4ca9d21f6cfa6 Mon Sep 17 00:00:00 2001
From: seankane-msft <seankane@microsoft.com>
Date: Mon, 9 Aug 2021 10:09:14 -0400
Subject: [PATCH 12/13] fix spelling, remove comment about nil

---
 sdk/azcore/etag.go | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/sdk/azcore/etag.go b/sdk/azcore/etag.go
index ad9306fe7a59..983af5b6524b 100644
--- a/sdk/azcore/etag.go
+++ b/sdk/azcore/etag.go
@@ -18,13 +18,13 @@ type ETag string
 const ETagAny ETag = "*"
 
 // Equals does a strong comparison of two ETags. Equals returns true when both
-// ETags are not weak and the values of the underlying strings are equal. If both ETags are "nil" they are considered equal
+// ETags are not weak and the values of the underlying strings are equal.
 func (e ETag) Equals(other ETag) bool {
 	return !e.IsWeak() && !other.IsWeak() && e == other
 }
 
-// WeakEquals does a weak compariosn of two ETags. Two ETags are equivalent if their opaque-tags match
-// character-by-character, regardless of either or both being tagged as "weak". If both ETags are "nil" they are considered equal
+// WeakEquals does a weak comparison of two ETags. Two ETags are equivalent if their opaque-tags match
+// character-by-character, regardless of either or both being tagged as "weak".
 func (e ETag) WeakEquals(other ETag) bool {
 	getStart := func(e1 ETag) int {
 		if e1.IsWeak() {

From ae8d2972891a889fe127754d165c2de612ebd935 Mon Sep 17 00:00:00 2001
From: seankane-msft <seankane@microsoft.com>
Date: Mon, 9 Aug 2021 10:37:11 -0400
Subject: [PATCH 13/13] format check

---
 sdk/azcore/etag_test.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sdk/azcore/etag_test.go b/sdk/azcore/etag_test.go
index 7cbd03fe6edd..5541fe05a20a 100644
--- a/sdk/azcore/etag_test.go
+++ b/sdk/azcore/etag_test.go
@@ -59,7 +59,7 @@ func TestETagEquality(t *testing.T) {
 	weakTagValidChars := createETag("W/\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\"")
 
 	require.Falsef(t, weakTag.Equals(weakTag), "Expected etags to not be equal")
-	require.Falsef(t, weakTag1.Equals( weakTag1), "Expected etags to not be equal")
+	require.Falsef(t, weakTag1.Equals(weakTag1), "Expected etags to not be equal")
 	require.Falsef(t, weakTag2.Equals(weakTag2), "Expected etags to not be equal")
 	require.Falsef(t, weakTagValidChars.Equals(weakTagValidChars), "Expected etags to not be equal")