Extend flux migrate to work with local files

Signed-off-by: Matheus Pimenta <matheuscscp@gmail.com>

cmd/flux/migrate_test.go

@@ -0,0 +1,161 @@
+/*
+Copyright 2025 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 main
+
+import (
+	"bytes"
+	"io/fs"
+	"os"
+	"testing"
+
+	. "github.com/onsi/gomega"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+)
+
+type writeToMemoryFS struct {
+	fs.FS
+
+	writtenFiles map[string][]byte
+}
+
+func (m *writeToMemoryFS) WriteFile(name string, data []byte, perm os.FileMode) error {
+	m.writtenFiles[name] = data
+	return nil
+}
+
+type writtenFile struct {
+	file       string
+	goldenFile string
+}
+
+func TestFileSystemMigrator(t *testing.T) {
+	for _, tt := range []struct {
+		name         string
+		path         string
+		outputGolden string
+		writtenFiles []writtenFile
+		err          string
+	}{
+		{
+			name: "errors out for single file that is a symlink",
+			path: "testdata/migrate/file-system/single-file-link.yaml",
+			err:  "file testdata/migrate/file-system/single-file-link.yaml is irregular",
+		},
+		{
+			name: "errors out for single file with wrong extension",
+			path: "testdata/migrate/file-system/single-file-wrong-ext.json",
+			err:  "file testdata/migrate/file-system/single-file-wrong-ext.json does not match the specified extensions: .yaml, .yml",
+		},
+		{
+			name:         "migrate single file",
+			path:         "testdata/migrate/file-system/single-file.yaml",
+			outputGolden: "testdata/migrate/file-system/single-file.yaml.output.golden",
+			writtenFiles: []writtenFile{
+				{
+					file:       "testdata/migrate/file-system/single-file.yaml",
+					goldenFile: "testdata/migrate/file-system/single-file.yaml.golden",
+				},
+			},
+		},
+		{
+			name:         "migrate files in directory",
+			path:         "testdata/migrate/file-system/dir",
+			outputGolden: "testdata/migrate/file-system/dir.output.golden",
+			writtenFiles: []writtenFile{
+				{
+					file:       "testdata/migrate/file-system/dir/some-dir/another-file.yaml",
+					goldenFile: "testdata/migrate/file-system/dir.golden/some-dir/another-file.yaml",
+				},
+				{
+					file:       "testdata/migrate/file-system/dir/some-dir/another-file.yml",
+					goldenFile: "testdata/migrate/file-system/dir.golden/some-dir/another-file.yml",
+				},
+				{
+					file:       "testdata/migrate/file-system/dir/some-file.yaml",
+					goldenFile: "testdata/migrate/file-system/dir.golden/some-file.yaml",
+				},
+				{
+					file:       "testdata/migrate/file-system/dir/some-file.yml",
+					goldenFile: "testdata/migrate/file-system/dir.golden/some-file.yml",
+				},
+			},
+		},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			g := NewWithT(t)
+
+			// Store logger, replace with test logger, and restore at the end of the test.
+			var testLogger bytes.Buffer
+			oldLogger := logger
+			logger = stderrLogger{&testLogger}
+			t.Cleanup(func() { logger = oldLogger })
+
+			// Open current working directory as root and build write-to-memory filesystem.
+			pathRoot, err := os.OpenRoot(".")
+			g.Expect(err).ToNot(HaveOccurred())
+			t.Cleanup(func() { pathRoot.Close() })
+			fileSystem := &writeToMemoryFS{
+				FS:           pathRoot.FS(),
+				writtenFiles: make(map[string][]byte),
+			}
+
+			// Prepare other inputs.
+			const yes = true
+			const dryRun = false
+			extensions := []string{".yaml", ".yml"}
+			latestVersions := map[schema.GroupKind]string{
+				{Group: "image.toolkit.fluxcd.io", Kind: "ImageRepository"}:       "v1",
+				{Group: "image.toolkit.fluxcd.io", Kind: "ImagePolicy"}:           "v1",
+				{Group: "image.toolkit.fluxcd.io", Kind: "ImageUpdateAutomation"}: "v1",
+			}
+
+			// Run migration.
+			err = NewFileSystemMigrator(fileSystem, yes, dryRun, tt.path, extensions, latestVersions).Run()
+			if tt.err != "" {
+				g.Expect(err).To(HaveOccurred())
+				g.Expect(err.Error()).To(Equal(tt.err))
+				return
+			}
+			g.Expect(err).ToNot(HaveOccurred())
+
+			// Assert logger output.
+			b, err := os.ReadFile(tt.outputGolden)
+			g.Expect(err).ToNot(HaveOccurred())
+			g.Expect(string(b)).To(Equal(testLogger.String()),
+				"logger output does not match golden file %s", tt.outputGolden)
+
+			// Assert which files were written.
+			writtenFiles := make([]string, 0, len(fileSystem.writtenFiles))
+			for name := range fileSystem.writtenFiles {
+				writtenFiles = append(writtenFiles, name)
+			}
+			expectedWrittenFiles := make([]string, 0, len(tt.writtenFiles))
+			for _, wf := range tt.writtenFiles {
+				expectedWrittenFiles = append(expectedWrittenFiles, wf.file)
+			}
+			g.Expect(writtenFiles).To(ConsistOf(expectedWrittenFiles))
+
+			// Assert contents of written files.
+			for _, wf := range tt.writtenFiles {
+				b, err := os.ReadFile(wf.goldenFile)
+				g.Expect(err).ToNot(HaveOccurred())
+				g.Expect(fileSystem.writtenFiles[wf.file]).To(Equal(b),
+					"file %s does not match golden file %s", wf.file, wf.goldenFile)
+			}
+		})
+	}
+}