From 43556c3c8dca6582ca2339e1ba2f143055d4711b Mon Sep 17 00:00:00 2001
From: Robbie McMichael <2044464+robbiemcmichael@users.noreply.github.com>
Date: Sat, 15 Nov 2025 12:34:34 +0800
Subject: [PATCH] Ensure deterministic order when diffing maps

When generating the diff for two maps where the map key is not a basic
type, the order is non-deterministic which makes the diffs unreadable.

By enabling the SpewKeys setting, the map keys will be spewed to strings
for the purpose of sorting them. This results in a deterministic order
and makes the diffs readable.
---
 assert/assertions.go      |  2 ++
 assert/assertions_test.go | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/assert/assertions.go b/assert/assertions.go
index a27e70546..dd0a71e2e 100644
--- a/assert/assertions.go
+++ b/assert/assertions.go
@@ -1985,6 +1985,7 @@ var spewConfig = spew.ConfigState{
 	DisablePointerAddresses: true,
 	DisableCapacities:       true,
 	SortKeys:                true,
+	SpewKeys:                true,
 	DisableMethods:          true,
 	MaxDepth:                10,
 }
@@ -1994,6 +1995,7 @@ var spewConfigStringerEnabled = spew.ConfigState{
 	DisablePointerAddresses: true,
 	DisableCapacities:       true,
 	SortKeys:                true,
+	SpewKeys:                true,
 	MaxDepth:                10,
 }
 
diff --git a/assert/assertions_test.go b/assert/assertions_test.go
index 4975f5e41..d1e57d6b3 100644
--- a/assert/assertions_test.go
+++ b/assert/assertions_test.go
@@ -2986,6 +2986,28 @@ Diff:
 
 	expected = `
 
+Diff:
+--- Expected
++++ Actual
+@@ -12,3 +12,3 @@
+   x: (int) 4
+- }: (int) 4
++ }: (int) 999
+ }
+`
+
+	type Key struct {
+		x int
+	}
+
+	actual = diff(
+		map[Key]int{Key{1}: 1, Key{2}: 2, Key{3}: 3, Key{4}: 4},
+		map[Key]int{Key{1}: 1, Key{2}: 2, Key{3}: 3, Key{4}: 999},
+	)
+	Equal(t, expected, actual)
+
+	expected = `
+
 Diff:
 --- Expected
 +++ Actual