Enable methods to sort map keys and spew itself as last resort

If enabled by flags, try to use methods to stringify map keys and sort on that.

If we can't use primitive sorting and we can't use methods, we can still fall
back on spew itself.  If SpewKeys is enabled, use Sprintf("%#v") to generate a
string and sort by that.

1 files changed, 120 insertions, 19 deletions

diff --git a/spew/common_test.go b/spew/common_test.go
index 8e741cd..39b7525 100644
--- a/spew/common_test.go
+++ b/spew/common_test.go
@@ -18,9 +18,10 @@ package spew_test
 
 import (
 	"fmt"
-	"github.com/davecgh/go-spew/spew"
 	"reflect"
 	"testing"
+
+	"github.com/davecgh/go-spew/spew"
 )
 
 // custom type to test Stinger interface on non-pointer receiver.
@@ -113,9 +114,24 @@ func testFailed(result string, wants []string) bool {
 	return true
 }
 
-// TestSortValues ensures the sort functionality for relect.Value based sorting
-// works as intended.
-func TestSortValues(t *testing.T) {
+type sortableStruct struct {
+	x int
+}
+
+func (ss sortableStruct) String() string {
+	return fmt.Sprintf("ss.%d", ss.x)
+}
+
+type unsortableStruct struct {
+	x int
+}
+
+type sortTestCase struct {
+	input    []reflect.Value
+	expected []reflect.Value
+}
+
+func helpTestSortValues(tests []sortTestCase, cs *spew.ConfigState, t *testing.T) {
 	getInterfaces := func(values []reflect.Value) []interface{} {
 		interfaces := []interface{}{}
 		for _, v := range values {
@@ -124,6 +140,23 @@ func TestSortValues(t *testing.T) {
 		return interfaces
 	}
 
+	for _, test := range tests {
+		spew.SortValues(test.input, cs)
+		// reflect.DeepEqual cannot really make sense of reflect.Value,
+		// probably because of all the pointer tricks. For instance,
+		// v(2.0) != v(2.0) on a 32-bits system. Turn them into interface{}
+		// instead.
+		input := getInterfaces(test.input)
+		expected := getInterfaces(test.expected)
+		if !reflect.DeepEqual(input, expected) {
+			t.Errorf("Sort mismatch:\n %v != %v", input, expected)
+		}
+	}
+}
+
+// TestSortValues ensures the sort functionality for relect.Value based sorting
+// works as intended.
+func TestSortValues(t *testing.T) {
 	v := reflect.ValueOf
 
 	a := v("a")
@@ -132,10 +165,7 @@ func TestSortValues(t *testing.T) {
 	embedA := v(embed{"a"})
 	embedB := v(embed{"b"})
 	embedC := v(embed{"c"})
-	tests := []struct {
-		input    []reflect.Value
-		expected []reflect.Value
-	}{
+	tests := []sortTestCase{
 		// No values.
 		{
 			[]reflect.Value{},
@@ -176,22 +206,93 @@ func TestSortValues(t *testing.T) {
 			[]reflect.Value{v(uintptr(2)), v(uintptr(1)), v(uintptr(3))},
 			[]reflect.Value{v(uintptr(1)), v(uintptr(2)), v(uintptr(3))},
 		},
+		// SortableStructs.
+		{
+			// Note: not sorted - DisableMethods is set.
+			[]reflect.Value{v(sortableStruct{2}), v(sortableStruct{1}), v(sortableStruct{3})},
+			[]reflect.Value{v(sortableStruct{2}), v(sortableStruct{1}), v(sortableStruct{3})},
+		},
+		// UnsortableStructs.
+		{
+			// Note: not sorted - SpewKeys is false.
+			[]reflect.Value{v(unsortableStruct{2}), v(unsortableStruct{1}), v(unsortableStruct{3})},
+			[]reflect.Value{v(unsortableStruct{2}), v(unsortableStruct{1}), v(unsortableStruct{3})},
+		},
 		// Invalid.
 		{
 			[]reflect.Value{embedB, embedA, embedC},
 			[]reflect.Value{embedB, embedA, embedC},
 		},
 	}
-	for _, test := range tests {
-		spew.SortValues(test.input)
-		// reflect.DeepEqual cannot really make sense of reflect.Value,
-		// probably because of all the pointer tricks. For instance,
-		// v(2.0) != v(2.0) on a 32-bits system. Turn them into interface{}
-		// instead.
-		input := getInterfaces(test.input)
-		expected := getInterfaces(test.expected)
-		if !reflect.DeepEqual(input, expected) {
-			t.Errorf("Sort mismatch:\n %v != %v", input, expected)
-		}
+	cs := spew.ConfigState{DisableMethods: true, SpewKeys: false}
+	helpTestSortValues(tests, &cs, t)
+}
+
+// TestSortValuesWithMethods ensures the sort functionality for relect.Value
+// based sorting works as intended when using string methods.
+func TestSortValuesWithMethods(t *testing.T) {
+	v := reflect.ValueOf
+
+	a := v("a")
+	b := v("b")
+	c := v("c")
+	tests := []sortTestCase{
+		// Ints.
+		{
+			[]reflect.Value{v(2), v(1), v(3)},
+			[]reflect.Value{v(1), v(2), v(3)},
+		},
+		// Strings.
+		{
+			[]reflect.Value{b, a, c},
+			[]reflect.Value{a, b, c},
+		},
+		// SortableStructs.
+		{
+			[]reflect.Value{v(sortableStruct{2}), v(sortableStruct{1}), v(sortableStruct{3})},
+			[]reflect.Value{v(sortableStruct{1}), v(sortableStruct{2}), v(sortableStruct{3})},
+		},
+		// UnsortableStructs.
+		{
+			// Note: not sorted - SpewKeys is false.
+			[]reflect.Value{v(unsortableStruct{2}), v(unsortableStruct{1}), v(unsortableStruct{3})},
+			[]reflect.Value{v(unsortableStruct{2}), v(unsortableStruct{1}), v(unsortableStruct{3})},
+		},
+	}
+	cs := spew.ConfigState{DisableMethods: false, SpewKeys: false}
+	helpTestSortValues(tests, &cs, t)
+}
+
+// TestSortValuesWithSpew ensures the sort functionality for relect.Value
+// based sorting works as intended when using spew to stringify keys.
+func TestSortValuesWithSpew(t *testing.T) {
+	v := reflect.ValueOf
+
+	a := v("a")
+	b := v("b")
+	c := v("c")
+	tests := []sortTestCase{
+		// Ints.
+		{
+			[]reflect.Value{v(2), v(1), v(3)},
+			[]reflect.Value{v(1), v(2), v(3)},
+		},
+		// Strings.
+		{
+			[]reflect.Value{b, a, c},
+			[]reflect.Value{a, b, c},
+		},
+		// SortableStructs.
+		{
+			[]reflect.Value{v(sortableStruct{2}), v(sortableStruct{1}), v(sortableStruct{3})},
+			[]reflect.Value{v(sortableStruct{1}), v(sortableStruct{2}), v(sortableStruct{3})},
+		},
+		// UnsortableStructs.
+		{
+			[]reflect.Value{v(unsortableStruct{2}), v(unsortableStruct{1}), v(unsortableStruct{3})},
+			[]reflect.Value{v(unsortableStruct{1}), v(unsortableStruct{2}), v(unsortableStruct{3})},
+		},
 	}
+	cs := spew.ConfigState{DisableMethods: true, SpewKeys: true}
+	helpTestSortValues(tests, &cs, t)
 }