Add a test case for #5904 (#3)

Author: tsekine354

api/krusty/list_order_test.go

@@ -0,0 +1,76 @@
+// Copyright 2022 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package krusty_test
+
+import (
+	"testing"
+
+	kusttest_test "sigs.k8s.io/kustomize/api/testutils/kusttest"
+)
+
+func TestStableListOrderAfterStrategicMergePatch(t *testing.T) {
+
+	th := kusttest_test.MakeHarness(t)
+	th.WriteF("base.yaml", `
+apiVersion: v1
+kind: Pod
+metadata:
+  name: example
+spec:
+  containers:
+  - name: example
+    env:
+    - name: ALFA
+      value: alfa
+    - name: BRAVO
+      value: bravo
+    - name: CHARLIE
+      value: charlie
+    - name: DELTA
+      value: delta
+    - name: LAST
+      value: "$(DELTA)$(ALFA)$(DELTA)"
+`)
+
+        th.WriteF("patch.yaml", `
+apiVersion: v1
+kind: Pod
+metadata:
+  name: example
+spec:
+  containers:
+  - name: example
+    env:
+    - name: LAST
+      value: "$(ALFA)$(DELTA)$(ALFA)"
+`)
+        th.WriteK(".", `
+resources:
+  - base.yaml
+patches:
+  - path: patch.yaml
+`)
+
+	m := th.Run(".", th.MakeDefaultOptions())
+	th.AssertActualEqualsExpected(m, `
+apiVersion: v1
+kind: Pod
+metadata:
+  name: example
+spec:
+  containers:
+  - name: example
+    env:
+    - name: ALFA
+      value: alfa
+    - name: BRAVO
+      value: bravo
+    - name: CHARLIE
+      value: charlie
+    - name: DELTA
+      value: delta
+    - name: LAST
+      value: "$(ALFA)$(DELTA)$(ALFA)"
+`)
+}