fix: time.Time rendering in the diff returned by error message

assert/assertions.go

@@ -1951,9 +1951,6 @@ func diff(expected interface{}, actual interface{}) string {
 	case reflect.TypeOf(""):
 		e = reflect.ValueOf(expected).String()
 		a = reflect.ValueOf(actual).String()
-	case reflect.TypeOf(time.Time{}):
-		e = spewConfigStringerEnabled.Sdump(expected)
-		a = spewConfigStringerEnabled.Sdump(actual)
 	default:
 		e = spewConfig.Sdump(expected)
 		a = spewConfig.Sdump(actual)
@@ -1985,14 +1982,7 @@ var spewConfig = spew.ConfigState{
 	DisableCapacities:       true,
 	SortKeys:                true,
 	DisableMethods:          true,
-	MaxDepth:                10,
-}
-
-var spewConfigStringerEnabled = spew.ConfigState{
-	Indent:                  " ",
-	DisablePointerAddresses: true,
-	DisableCapacities:       true,
-	SortKeys:                true,
+	EnableTimeStringer:      true,
 	MaxDepth:                10,
 }
 

assert/assertions_test.go

@@ -3036,6 +3036,30 @@ Diff:
 		time.Date(2020, 9, 25, 0, 0, 0, 0, time.UTC),
 	)
 	Equal(t, expected, actual)
+
+	expected = `
+
+Diff:
+--- Expected
++++ Actual
+@@ -1,3 +1,3 @@
+ (assert.someStruct) {
+- t: (time.Time) 2020-09-24 00:00:00 +0000 UTC
++ t: (time.Time) 2020-09-25 00:00:00 +0000 UTC
+ }
+`
+
+	type someStruct struct {
+		t time.Time
+	}
+
+	actual = diff(
+		someStruct{t: time.Date(2020, 9, 24, 0, 0, 0, 0, time.UTC)},
+		someStruct{t: time.Date(2020, 9, 25, 0, 0, 0, 0, time.UTC)},
+	)
+
+	Equal(t, expected, actual)
+
 }
 
 func TestTimeEqualityErrorFormatting(t *testing.T) {

internal/spew/common.go

@@ -271,6 +271,12 @@ func canSortSimply(kind reflect.Kind) bool {
 	case reflect.Array:
 		return true
 	}
+
+	if kind == reflect.Struct && kind.String() == "time.Time" {
+		// time.Time values can be sorted directly, as it implements [sort.Interface].
+		return true
+	}
+
 	return false
 }
 

internal/spew/config.go

@@ -53,6 +53,12 @@ type ConfigState struct {
 	// invoked for types that implement them.
 	DisableMethods bool
 
+	// EnableTimeStringer specifies whether to invoke the Stringer interface on
+	// time.Time values even when DisableMethods is true. This is useful to get
+	// human-readable output for time.Time values while keeping method calls
+	// disabled for other types.
+	EnableTimeStringer bool
+
 	// DisablePointerMethods specifies whether or not to check for and invoke
 	// error and Stringer interfaces on types which only accept a pointer
 	// receiver when the current type is not a pointer.

internal/spew/dump.go

@@ -301,7 +301,7 @@ func (d *dumpState) dump(v reflect.Value) {
 
 	// Call Stringer/error interfaces if they exist and the handle methods flag
 	// is enabled
-	if !d.cs.DisableMethods {
+	if !d.cs.DisableMethods || (d.cs.EnableTimeStringer && v.Type().String() == "time.Time") {
 		if (kind != reflect.Invalid) && (kind != reflect.Interface) {
 			if handled := handleMethods(d.cs, d.w, v); handled {
 				return

internal/spew/format.go

@@ -222,7 +222,7 @@ func (f *formatState) format(v reflect.Value) {
 
 	// Call Stringer/error interfaces if they exist and the handle methods
 	// flag is enabled.
-	if !f.cs.DisableMethods {
+	if !f.cs.DisableMethods || (f.cs.EnableTimeStringer && v.Type().String() == "time.Time") {
 		if (kind != reflect.Invalid) && (kind != reflect.Interface) {
 			if handled := handleMethods(f.cs, f.fs, v); handled {
 				return

internal/spew/spew_test.go

@@ -22,6 +22,7 @@ import (
 	"io/ioutil"
 	"os"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/internal/spew"
 )
@@ -127,6 +128,7 @@ func initSpewTests() {
 	// Config states with various settings.
 	scsDefault := spew.NewDefaultConfig()
 	scsNoMethods := &spew.ConfigState{Indent: " ", DisableMethods: true}
+	scsNoMethodsButTimeStringer := &spew.ConfigState{Indent: " ", DisableMethods: true, EnableTimeStringer: true}
 	scsNoPmethods := &spew.ConfigState{Indent: " ", DisablePointerMethods: true}
 	scsMaxDepth := &spew.ConfigState{Indent: " ", MaxDepth: 1}
 	scsContinue := &spew.ConfigState{Indent: " ", ContinueOnMethod: true}
@@ -138,6 +140,8 @@ func initSpewTests() {
 	ts := stringer("test")
 	tps := pstringer("test")
 
+	tm := time.Date(2006, time.January, 2, 15, 4, 5, 999999999, time.UTC)
+
 	type ptrTester struct {
 		s *struct{}
 	}
@@ -203,6 +207,11 @@ func initSpewTests() {
 		{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"},
+
+		// time.Time formatting:
+		{scsDefault, fCSFprint, "", tm, "2006-01-02 15:04:05.999999999 +0000 UTC"},
+		{scsNoMethods, fCSFprint, "", tm, "{999999999 63271811045 <nil>}"},
+		{scsNoMethodsButTimeStringer, fCSFprint, "", tm, "2006-01-02 15:04:05.999999999 +0000 UTC"},
 	}
 }