kuberc: pick the first known version when decoding + tests

Signed-off-by: Maciej Szulik <soltysh@gmail.com>

staging/src/k8s.io/kubectl/pkg/kuberc/marshal.go

@@ -88,13 +88,14 @@ func decodePreference(kubercFile string) (*config.Preference, error) {
 		}
 
 		// we have a usable preferences to return
-		klog.V(5).Infof("kuberc: successfully decoded entry %d in %s", attemptedItems, kubercFile)
+		klog.V(5).Infof("kuberc: using entry %d (%s) in %s", attemptedItems, gvk.GroupVersion(), kubercFile)
 		return preferences, strictDecodeErr
-
 	}
+
 	if attemptedItems > 0 {
 		return nil, fmt.Errorf("no valid preferences found in %s, use --v=5 to see details", kubercFile)
 	}
+
 	// empty doc
 	klog.V(5).Infof("kuberc: no preferences found in %s", kubercFile)
 	return nil, nil

staging/src/k8s.io/kubectl/pkg/kuberc/marshal_test.go

@@ -0,0 +1,103 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package kuberc
+
+import (
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestDecodePreference(t *testing.T) {
+	testCases := map[string]struct {
+		kuberc           string
+		expectedAliases  []string
+		expectedDefaults []string
+		expectedError    string
+	}{
+		"v1alpha1": {
+			kuberc:           filepath.Join("..", "..", "testdata", "kuberc", "v1alpha1.kuberc"),
+			expectedDefaults: []string{"v1alpha1-apply", "v1alpha1-delete"},
+		},
+		"v1beta1": {
+			kuberc:           filepath.Join("..", "..", "testdata", "kuberc", "v1beta1.kuberc"),
+			expectedDefaults: []string{"v1beta1-apply", "v1beta1-delete"},
+		},
+		"first known version (v1beta1) with all versions": {
+			kuberc:           filepath.Join("..", "..", "testdata", "kuberc", "allversions.kuberc"),
+			expectedAliases:  []string{"getn", "runx"},
+			expectedDefaults: []string{"v1beta1-apply", "v1beta1-delete"},
+		},
+		"first known (v1beta1) with multiple versions (unknown, v1beta1, v1alpha1)": {
+			kuberc:           filepath.Join("..", "..", "testdata", "kuberc", "multiple1.kuberc"),
+			expectedDefaults: []string{"v1beta1-apply", "v1beta1-delete"},
+		},
+		"first known (v1beta1) with multiple versions (unknown, v1beta1, v1beta1, v1alpha1)": {
+			kuberc:           filepath.Join("..", "..", "testdata", "kuberc", "multiple2.kuberc"),
+			expectedDefaults: []string{"v1beta1-apply-first", "v1beta1-delete-first"},
+		},
+		"first known older (v1alpha1) with multiple versions (unknown, v1alpha1)": {
+			kuberc:           filepath.Join("..", "..", "testdata", "kuberc", "multiple3.kuberc"),
+			expectedDefaults: []string{"v1alpha1-apply-first", "v1alpha1-delete-first"},
+		},
+		"first v1alpha1 with multiple versions (unknown, v1alpha1, v1beta1)": {
+			kuberc:           filepath.Join("..", "..", "testdata", "kuberc", "multiple4.kuberc"),
+			expectedDefaults: []string{"v1alpha1-apply-first", "v1alpha1-delete-first"},
+		},
+		"single unknown version": {
+			kuberc:        filepath.Join("..", "..", "testdata", "kuberc", "unknown.kuberc"),
+			expectedError: "no valid preferences found",
+		},
+		"multiple unknown version": {
+			kuberc:        filepath.Join("..", "..", "testdata", "kuberc", "unknown.kuberc"),
+			expectedError: "no valid preferences found",
+		},
+		"non-existent file": {
+			kuberc:        filepath.Join("..", "..", "testdata", "kuberc", "non-existent"),
+			expectedError: "no such file or directory",
+		},
+	}
+
+	for name, tc := range testCases {
+		t.Run(name, func(t *testing.T) {
+			actual, err := decodePreference(tc.kuberc)
+			if len(tc.expectedError) != 0 {
+				require.ErrorContains(t, err, tc.expectedError, "wrong expected error")
+				return
+			}
+			require.NoError(t, err, "unexpected error")
+			require.NotNil(t, actual, "missing preferences when decoding")
+			defaults := []string{}
+			for _, o := range actual.Defaults {
+				defaults = append(defaults, o.Command)
+			}
+			require.ElementsMatch(t, defaults, tc.expectedDefaults, "defaults mismatch")
+			aliases := []string{}
+			for _, o := range actual.Aliases {
+				aliases = append(aliases, o.Name)
+			}
+			require.ElementsMatch(t, aliases, tc.expectedAliases, "aliases mismatch")
+		})
+	}
+}
+
+func TestDecodeEmptyPreference(t *testing.T) {
+	actual, err := decodePreference(filepath.Join("..", "..", "testdata", "kuberc", "empty.kuberc"))
+	require.NoError(t, err, "unexpected error")
+	require.Nil(t, actual, "unexpected preferences")
+}

staging/src/k8s.io/kubectl/testdata/kuberc/allversions.kuberc

@@ -0,0 +1,34 @@
+---
+apiVersion: kubectl.config.k8s.io/v1beta1
+kind: Preference
+aliases:
+  - name: getn
+    command: get
+    prependArgs:
+    - namespace
+  - name: runx
+    command: run
+    appendArgs:
+      - --
+      - custom-arg
+defaults:
+  - command: v1beta1-apply
+    options:
+      - name: server-side
+        default: "true"
+  - command: v1beta1-delete
+    options:
+      - name: interactive
+        default: "true"
+---
+apiVersion: kubectl.config.k8s.io/v1alpha1
+kind: Preference
+overrides:
+  - command: v1alpha1-apply
+    flags:
+      - name: server-side
+        default: "true"
+  - command: v1alpha1-delete
+    flags:
+      - name: interactive
+        default: "true"

staging/src/k8s.io/kubectl/testdata/kuberc/multiple1.kuberc

@@ -0,0 +1,36 @@
+---
+apiVersion: kubectl.config.k8s.io/v1unknown1
+kind: Preference
+overrides:
+  - command: v1unknown1-apply
+    flags:
+      - name: server-side
+        default: "true"
+  - command: v1unknown1-delete
+    flags:
+      - name: interactive
+        default: "true"
+---
+apiVersion: kubectl.config.k8s.io/v1beta1
+kind: Preference
+defaults:
+  - command: v1beta1-apply
+    options:
+      - name: server-side
+        default: "true"
+  - command: v1beta1-delete
+    options:
+      - name: interactive
+        default: "true"
+---
+apiVersion: kubectl.config.k8s.io/v1alpha1
+kind: Preference
+overrides:
+  - command: v1alpha1-apply
+    flags:
+      - name: server-side
+        default: "true"
+  - command: v1alpha1-delete
+    flags:
+      - name: interactive
+        default: "true"

staging/src/k8s.io/kubectl/testdata/kuberc/multiple2.kuberc

@@ -0,0 +1,42 @@
+---
+apiVersion: kubectl.config.k8s.io/v1unknown1
+kind: Preference
+overrides:
+  - command: v1unknown1-apply
+    flags:
+      - name: server-side
+        default: "true"
+  - command: v1unknown1-delete
+    flags:
+      - name: interactive
+        default: "true"
+---
+apiVersion: kubectl.config.k8s.io/v1beta1
+kind: Preference
+defaults:
+  - command: v1beta1-apply-first
+    options:
+      - name: server-side
+        default: "true"
+  - command: v1beta1-delete-first
+---
+apiVersion: kubectl.config.k8s.io/v1beta1
+kind: Preference
+defaults:
+  - command: v1beta1-apply-second
+    options:
+      - name: server-side
+        default: "true"
+  - command: v1beta1-delete-second
+---
+apiVersion: kubectl.config.k8s.io/v1alpha1
+kind: Preference
+overrides:
+  - command: v1alpha1-apply
+    flags:
+      - name: server-side
+        default: "true"
+  - command: v1alpha1-delete
+    flags:
+      - name: interactive
+        default: "true"

staging/src/k8s.io/kubectl/testdata/kuberc/multiple3.kuberc

@@ -0,0 +1,36 @@
+---
+apiVersion: kubectl.config.k8s.io/v1unknown1
+kind: Preference
+overrides:
+  - command: v1unknown1-apply
+    flags:
+      - name: server-side
+        default: "true"
+  - command: v1unknown1-delete
+    flags:
+      - name: interactive
+        default: "true"
+---
+apiVersion: kubectl.config.k8s.io/v1alpha1
+kind: Preference
+overrides:
+  - command: v1alpha1-apply-first
+    flags:
+      - name: server-side
+        default: "true"
+  - command: v1alpha1-delete-first
+    flags:
+      - name: interactive
+        default: "true"
+---
+apiVersion: kubectl.config.k8s.io/v1alpha1
+kind: Preference
+overrides:
+  - command: v1alpha1-apply-second
+    flags:
+      - name: server-side
+        default: "true"
+  - command: v1alpha1-delete-second
+    flags:
+      - name: interactive
+        default: "true"

staging/src/k8s.io/kubectl/testdata/kuberc/multiple4.kuberc

@@ -0,0 +1,45 @@
+---
+apiVersion: kubectl.config.k8s.io/v1unknown1
+kind: Preference
+overrides:
+  - command: v1unknown1-apply
+    flags:
+      - name: server-side
+        default: "true"
+  - command: v1unknown1-delete
+    flags:
+      - name: interactive
+        default: "true"
+---
+apiVersion: kubectl.config.k8s.io/v1alpha1
+kind: Preference
+overrides:
+  - command: v1alpha1-apply-first
+    flags:
+      - name: server-side
+        default: "true"
+  - command: v1alpha1-delete-first
+    flags:
+      - name: interactive
+        default: "true"
+---
+apiVersion: kubectl.config.k8s.io/v1alpha1
+kind: Preference
+overrides:
+  - command: v1alpha1-apply-second
+    flags:
+      - name: server-side
+        default: "true"
+  - command: v1alpha1-delete-second
+    flags:
+      - name: interactive
+        default: "true"
+---
+apiVersion: kubectl.config.k8s.io/v1beta1
+kind: Preference
+defaults:
+  - command: v1beta1-apply-first
+    options:
+      - name: server-side
+        default: "true"
+  - command: v1beta1-delete-first

staging/src/k8s.io/kubectl/testdata/kuberc/unknown.kuberc

@@ -0,0 +1,11 @@
+apiVersion: kubectl.config.k8s.io/v1unknown1
+kind: Preference
+overrides:
+  - command: v1unknown1-apply
+    flags:
+      - name: server-side
+        default: "true"
+  - command: v1unknown1-delete
+    flags:
+      - name: interactive
+        default: "true"

staging/src/k8s.io/kubectl/testdata/kuberc/unknown2.kuberc

@@ -0,0 +1,24 @@
+---
+apiVersion: kubectl.config.k8s.io/v1unknown1
+kind: Preference
+overrides:
+  - command: v1unknown1-apply
+    flags:
+      - name: server-side
+        default: "true"
+  - command: v1unknown1-delete
+    flags:
+      - name: interactive
+        default: "true"
+---
+apiVersion: kubectl.config.k8s.io/v1unknown2
+kind: Preference
+overrides:
+  - command: v1unknown2-apply
+    flags:
+      - name: server-side
+        default: "true"
+  - command: v1unknown2-delete
+    flags:
+      - name: interactive
+        default: "true"

staging/src/k8s.io/kubectl/testdata/kuberc/v1alpha1.kuberc

@@ -0,0 +1,11 @@
+apiVersion: kubectl.config.k8s.io/v1alpha1
+kind: Preference
+overrides:
+  - command: v1alpha1-apply
+    flags:
+      - name: server-side
+        default: "true"
+  - command: v1alpha1-delete
+    flags:
+      - name: interactive
+        default: "true"

staging/src/k8s.io/kubectl/testdata/kuberc/v1beta1.kuberc

@@ -0,0 +1,11 @@
+apiVersion: kubectl.config.k8s.io/v1beta1
+kind: Preference
+defaults:
+  - command: v1beta1-apply
+    options:
+      - name: server-side
+        default: "true"
+  - command: v1beta1-delete
+    options:
+      - name: interactive
+        default: "true"