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, 48 insertions, 1 deletions

diff --git a/spew/format_test.go b/spew/format_test.go
index 4dd0ac2..b0f9761 100644
--- a/spew/format_test.go
+++ b/spew/format_test.go
@@ -69,9 +69,10 @@ package spew_test
 import (
 	"bytes"
 	"fmt"
-	"github.com/davecgh/go-spew/spew"
 	"testing"
 	"unsafe"
+
+	"github.com/davecgh/go-spew/spew"
 )
 
 // formatterTest is used to describe a test to be perfomed against NewFormatter.
@@ -1478,6 +1479,22 @@ func TestFormatter(t *testing.T) {
 	}
 }
 
+type testStruct struct {
+	x int
+}
+
+func (ts testStruct) String() string {
+	return fmt.Sprintf("ts.%d", ts.x)
+}
+
+type testStructP struct {
+	x int
+}
+
+func (ts *testStructP) String() string {
+	return fmt.Sprintf("ts.%d", ts.x)
+}
+
 func TestPrintSortedKeys(t *testing.T) {
 	cfg := spew.ConfigState{SortKeys: true}
 	s := cfg.Sprint(map[int]string{1: "1", 3: "3", 2: "2"})
@@ -1485,4 +1502,34 @@ func TestPrintSortedKeys(t *testing.T) {
 	if s != expected {
 		t.Errorf("Sorted keys mismatch:\n  %v %v", s, expected)
 	}
+
+	s = cfg.Sprint(map[stringer]int{"1": 1, "3": 3, "2": 2})
+	expected = "map[stringer 1:1 stringer 2:2 stringer 3:3]"
+	if s != expected {
+		t.Errorf("Sorted keys mismatch:\n  %v %v", s, expected)
+	}
+
+	s = cfg.Sprint(map[pstringer]int{pstringer("1"): 1, pstringer("3"): 3, pstringer("2"): 2})
+	expected = "map[stringer 1:1 stringer 2:2 stringer 3:3]"
+	if s != expected {
+		t.Errorf("Sorted keys mismatch:\n  %v %v", s, expected)
+	}
+
+	s = cfg.Sprint(map[testStruct]int{testStruct{1}: 1, testStruct{3}: 3, testStruct{2}: 2})
+	expected = "map[ts.1:1 ts.2:2 ts.3:3]"
+	if s != expected {
+		t.Errorf("Sorted keys mismatch:\n  %v %v", s, expected)
+	}
+
+	s = cfg.Sprint(map[testStructP]int{testStructP{1}: 1, testStructP{3}: 3, testStructP{2}: 2})
+	expected = "map[ts.1:1 ts.2:2 ts.3:3]"
+	if s != expected {
+		t.Errorf("Sorted keys mismatch:\n  %v %v", s, expected)
+	}
+
+	s = cfg.Sprint(map[customError]int{customError(1): 1, customError(3): 3, customError(2): 2})
+	expected = "map[error: 1:1 error: 2:2 error: 3:3]"
+	if s != expected {
+		t.Errorf("Sorted keys mismatch:\n  %v %v", s, expected)
+	}
 }