oauth2: drop dependency on go-cmp

For golang/oauth2#615

Change-Id: I1e17703f5a52240cbd7802ab1da1fd8b24be8d6c
Reviewed-on: https://go-review.googlesource.com/c/oauth2/+/666816
Reviewed-by: Junyang Shao <shaojunyang@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Matt Hickford <matt.hickford@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

deviceauth_test.go

@@ -7,9 +7,6 @@ import (
 	"strings"
 	"testing"
 	"time"
-
-	"github.com/google/go-cmp/cmp"
-	"github.com/google/go-cmp/cmp/cmpopts"
 )
 
 func TestDeviceAuthResponseMarshalJson(t *testing.T) {
@@ -74,7 +71,16 @@ func TestDeviceAuthResponseUnmarshalJson(t *testing.T) {
 			if err != nil {
 				t.Fatal(err)
 			}
-			if !cmp.Equal(got, tc.want, cmpopts.IgnoreUnexported(DeviceAuthResponse{}), cmpopts.EquateApproxTime(time.Second+time.Since(begin))) {
+			margin := time.Second + time.Since(begin)
+			timeDiff := got.Expiry.Sub(tc.want.Expiry)
+			if timeDiff < 0 {
+				timeDiff *= -1
+			}
+			if timeDiff > margin {
+				t.Errorf("expiry time difference too large, got=%v, want=%v margin=%v", got.Expiry, tc.want.Expiry, margin)
+			}
+			got.Expiry, tc.want.Expiry = time.Time{}, time.Time{}
+			if got != tc.want {
 				t.Errorf("want=%#v, got=%#v", tc.want, got)
 			}
 		})

go.mod

@@ -2,7 +2,4 @@ module golang.org/x/oauth2
 
 go 1.23.0
 
-require (
+require cloud.google.com/go/compute/metadata v0.3.0
-	cloud.google.com/go/compute/metadata v0.3.0
-	github.com/google/go-cmp v0.5.9
-)

go.sum

@@ -1,4 +1,2 @@
 cloud.google.com/go/compute/metadata v0.3.0 h1:Tz+eQXMEqDIKRsmY3cHTL6FVaynIjX2QxYC4trgAKZc=
 cloud.google.com/go/compute/metadata v0.3.0/go.mod h1:zFmK7XCadkQkj6TtorcaGlCW1hT1fIilQDwofLpJ20k=
-github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
-github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=

google/externalaccount/executablecredsource_test.go

@@ -9,11 +9,9 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
-	"sort"
+	"slices"
 	"testing"
 	"time"
-
-	"github.com/google/go-cmp/cmp"
 )
 
 type testEnvironment struct {
@@ -253,14 +251,12 @@ func TestExecutableCredentialGetEnvironment(t *testing.T) {
 
 			ecs.env = &tt.environment
 
-			// This Transformer sorts a []string.
+			got := ecs.executableEnvironment()
-			sorter := cmp.Transformer("Sort", func(in []string) []string {
+			slices.Sort(got)
-				out := append([]string(nil), in...) // Copy input to avoid mutating it
+			want := tt.expectedEnvironment
-				sort.Strings(out)
+			slices.Sort(want)
-				return out
-			})
 
-			if got, want := ecs.executableEnvironment(), tt.expectedEnvironment; !cmp.Equal(got, want, sorter) {
+			if !slices.Equal(got, want) {
 				t.Errorf("Incorrect environment received.\nReceived: %s\nExpected: %s", got, want)
 			}
 		})

google/externalaccount/header_test.go

@@ -7,8 +7,6 @@ package externalaccount
 import (
 	"runtime"
 	"testing"
-
-	"github.com/google/go-cmp/cmp"
 )
 
 func TestGoVersion(t *testing.T) {
@@ -40,8 +38,8 @@ func TestGoVersion(t *testing.T) {
 	} {
 		version = tst.v
 		got := goVersion()
-		if diff := cmp.Diff(got, tst.want); diff != "" {
+		if got != tst.want {
-			t.Errorf("got(-),want(+):\n%s", diff)
+			t.Errorf("go version = %q, want = %q", got, tst.want)
 		}
 	}
 	version = runtime.Version