feat: add CLI command for importing and exporting Pocket ID data (#998)

Co-authored-by: Alessandro (Ale) Segala <43508+ItalyPaleAle@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

backend/resources/files_test.go

@@ -0,0 +1,72 @@
+package resources
+
+import (
+	"embed"
+	"slices"
+	"strconv"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// This test is meant to enforce that for every new migration added, a file with the same migration number exists for all supported databases
+// This is necessary to ensure import/export works correctly
+// Note: if a migration is not needed for a database, ensure there's a file with an empty (no-op) migration (e.g. even just a comment)
+func TestMigrationsMatchingVersions(t *testing.T) {
+	// We can ignore migrations with version below 20251115000000
+	const ignoreBefore = 20251115000000
+
+	// Scan postgres migrations
+	postgresMigrations := scanMigrations(t, FS, "migrations/postgres", ignoreBefore)
+
+	// Scan sqlite migrations
+	sqliteMigrations := scanMigrations(t, FS, "migrations/sqlite", ignoreBefore)
+
+	// Sort both lists for consistent comparison
+	slices.Sort(postgresMigrations)
+	slices.Sort(sqliteMigrations)
+
+	// Compare the lists
+	assert.Equal(t, postgresMigrations, sqliteMigrations, "Migration versions must match between Postgres and SQLite")
+}
+
+// scanMigrations scans a directory for migration files and returns a list of versions
+func scanMigrations(t *testing.T, fs embed.FS, dir string, ignoreBefore int64) []int64 {
+	t.Helper()
+
+	entries, err := fs.ReadDir(dir)
+	require.NoErrorf(t, err, "Failed to read directory '%s'", dir)
+
+	// Divide by 2 because of up and down files
+	versions := make([]int64, 0, len(entries)/2)
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+
+		filename := entry.Name()
+
+		// Only consider .up.sql files
+		if !strings.HasSuffix(filename, ".up.sql") {
+			continue
+		}
+
+		// Extract version from filename (format: <version>_<anything>.up.sql)
+		versionString, _, ok := strings.Cut(filename, "_")
+		require.Truef(t, ok, "Migration file has unexpected format: %s", filename)
+
+		version, err := strconv.ParseInt(versionString, 10, 64)
+		require.NoErrorf(t, err, "Failed to parse version from filename '%s'", filename)
+
+		// Exclude migrations with version below ignoreBefore
+		if version < ignoreBefore {
+			continue
+		}
+
+		versions = append(versions, version)
+	}
+
+	return versions
+}