Move some code to make it reusable without import cycles.

kyaml/yaml/datamap_test.go

@@ -0,0 +1,38 @@
+// Copyright 2021 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package yaml_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+func TestSortedKeys(t *testing.T) {
+	testCases := map[string]struct {
+		input    map[string]string
+		expected []string
+	}{
+		"empty": {
+			input:    map[string]string{},
+			expected: []string{}},
+		"one": {
+			input:    map[string]string{"a": "aaa"},
+			expected: []string{"a"}},
+		"three": {
+			input:    map[string]string{"c": "ccc", "b": "bbb", "a": "aaa"},
+			expected: []string{"a", "b", "c"}},
+	}
+	for tn, tc := range testCases {
+		tc := tc
+		t.Run(tn, func(t *testing.T) {
+			if !assert.Equal(t,
+				yaml.SortedMapKeys(tc.input),
+				tc.expected) {
+				t.FailNow()
+			}
+		})
+	}
+}