fix: update flux apply and tests to ensure updates fail if broken (#169)

<!-- markdownlint-disable MD041 -->
#### What this PR does / why we need it

#### Which issue(s) this PR fixes
<!--
Usage: `Fixes #<issue number>`, or `Fixes (paste link of issue)`.
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---------

Signed-off-by: Gergely Brautigam <[email protected]>

Author: Skarlso

.github/workflows/test.yml

@@ -0,0 +1,32 @@
+name: Test
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    
+    steps:
+    - uses: actions/checkout@v4
+    
+    - name: Set up Go
+      uses: actions/setup-go@v5
+      with:
+        go-version: '1.24.2'
+        
+    - name: Cache Go modules
+      uses: actions/cache@v4
+      with:
+        path: |
+          ~/.cache/go-build
+          ~/go/pkg/mod
+        key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+        restore-keys: |
+          ${{ runner.os }}-go-
+
+    - name: Run tests
+      run: make test-unit

Makefile

@@ -34,3 +34,7 @@ vet: ## Run go vet against code.
 test: ## Run all of the tests
 	go test ./...
 
+.PHONY: test-unit
+test-unit: ## Run unit tests only
+	go test ./internal/... -short
+

go.mod

@@ -24,6 +24,7 @@ require (
 	github.com/open-component-model/git-controller v0.12.1
 	github.com/open-component-model/ocm-controller v0.26.5
 	github.com/open-component-model/replication-controller v0.13.1
+	github.com/stretchr/testify v1.10.0
 	k8s.io/api v0.33.3
 	k8s.io/apiextensions-apiserver v0.33.3
 	k8s.io/apimachinery v0.33.3
@@ -269,6 +270,7 @@ require (
 	github.com/peterbourgon/diskv v2.0.1+incompatible // indirect
 	github.com/pjbgf/sha1cd v0.3.2 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
+	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/prometheus/client_golang v1.22.0 // indirect
 	github.com/prometheus/client_model v0.6.2 // indirect
 	github.com/prometheus/common v0.65.0 // indirect

internal/utils/flux_apply.go

@@ -26,6 +26,7 @@ import (
 	"time"
 
 	"github.com/fluxcd/cli-utils/pkg/kstatus/polling"
+	"github.com/fluxcd/pkg/ssa/normalize"
 	"github.com/fluxcd/pkg/ssa/utils"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/cli-runtime/pkg/genericclioptions"
@@ -49,7 +50,7 @@ func Apply(ctx context.Context, rcg genericclioptions.RESTClientGetter, opts *ru
 		return "", fmt.Errorf("no Kubernetes objects found at: %s", manifestPath)
 	}
 
-	if err := ssa.SetNativeKindsDefaults(objs); err != nil {
+	if err := normalize.UnstructuredList(objs); err != nil {
 		return "", err
 	}
 

internal/utils/flux_apply_test.go

@@ -0,0 +1,148 @@
+/*
+Copyright 2021 The Flux 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 utils
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestIsRecognizedKustomizationFile(t *testing.T) {
+	tests := []struct {
+		name     string
+		path     string
+		expected bool
+	}{
+		{
+			name:     "kustomization.yaml",
+			path:     "/path/to/kustomization.yaml",
+			expected: true,
+		},
+		{
+			name:     "kustomization.yml",
+			path:     "/path/to/kustomization.yml",
+			expected: true,
+		},
+		{
+			name:     "Kustomization",
+			path:     "/path/to/Kustomization",
+			expected: true,
+		},
+		{
+			name:     "regular yaml file",
+			path:     "/path/to/deployment.yaml",
+			expected: false,
+		},
+		{
+			name:     "no extension",
+			path:     "/path/to/somefile",
+			expected: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := isRecognizedKustomizationFile(tt.path)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func TestReadObjects(t *testing.T) {
+	tests := []struct {
+		name        string
+		setupFile   func(t *testing.T) (root, manifestPath string)
+		expectError bool
+	}{
+		{
+			name: "valid yaml file",
+			setupFile: func(t *testing.T) (string, string) {
+				dir := t.TempDir()
+				manifestPath := filepath.Join(dir, "test.yaml")
+				content := `apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: test-cm
+  namespace: default
+data:
+  key: value`
+				require.NoError(t, os.WriteFile(manifestPath, []byte(content), 0644))
+				return dir, manifestPath
+			},
+			expectError: false,
+		},
+		{
+			name: "directory instead of file",
+			setupFile: func(t *testing.T) (string, string) {
+				dir := t.TempDir()
+				subDir := filepath.Join(dir, "subdir")
+				require.NoError(t, os.Mkdir(subDir, 0755))
+				return dir, subDir
+			},
+			expectError: true,
+		},
+		{
+			name: "non-existent file",
+			setupFile: func(t *testing.T) (string, string) {
+				dir := t.TempDir()
+				return dir, filepath.Join(dir, "missing.yaml")
+			},
+			expectError: true,
+		},
+		{
+			name: "kustomization file",
+			setupFile: func(t *testing.T) (string, string) {
+				dir := t.TempDir()
+				kustomizationPath := filepath.Join(dir, "kustomization.yaml")
+				content := `apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+resources:
+- deployment.yaml`
+				require.NoError(t, os.WriteFile(kustomizationPath, []byte(content), 0644))
+				
+				deploymentPath := filepath.Join(dir, "deployment.yaml")
+				deploymentContent := `apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: test-deployment`
+				require.NoError(t, os.WriteFile(deploymentPath, []byte(deploymentContent), 0644))
+				return dir, kustomizationPath
+			},
+			expectError: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			root, manifestPath := tt.setupFile(t)
+			
+			objects, err := readObjects(root, manifestPath)
+			
+			if tt.expectError {
+				require.Error(t, err)
+				assert.Nil(t, objects)
+			} else {
+				require.NoError(t, err)
+				assert.NotEmpty(t, objects)
+			}
+		})
+	}
+}