feat(scanner): add fuzzing test

server/scanner/scanner_fuzz_test.go

@@ -0,0 +1,90 @@
+//go:build go1.18
+// +build go1.18
+
+package scanner_test
+
+import (
+	"encoding/binary"
+	"fmt"
+	"math/rand"
+	"reflect"
+	"testing"
+
+	_ "github.com/jinzhu/gorm/dialects/sqlite"
+	"github.com/matryer/is"
+	"go.senan.xyz/gonic/server/mockfs"
+)
+
+func FuzzScanner(f *testing.F) {
+	checkDelta := func(is *is.I, m *mockfs.MockFS, expSeen, expNew int) {
+		is.Helper()
+
+		ctx := m.ScanAndClean()
+		is.Equal(ctx.SeenTracks(), expSeen)
+		is.Equal(ctx.SeenTracksNew(), expNew)
+		is.Equal(ctx.TracksMissing(), 0)
+		is.Equal(ctx.AlbumsMissing(), 0)
+		is.Equal(ctx.ArtistsMissing(), 0)
+		is.Equal(ctx.GenresMissing(), 0)
+	}
+
+	f.Fuzz(func(t *testing.T, data []byte) {
+		is := is.NewRelaxed(t)
+		m := mockfs.New(t)
+		defer m.CleanUp()
+
+		const toAdd = 1000
+		for i := 0; i < toAdd; i++ {
+			path := fmt.Sprintf("artist-%d/album-%d/track-%d.flac", i/6, i/3, i)
+			m.AddTrack(path)
+			m.SetTags(path, func(tags *mockfs.Tags) { fuzzStruct(i, data, tags) })
+		}
+
+		checkDelta(is, m, toAdd, toAdd) // we added all tracks, 0 delta
+		checkDelta(is, m, toAdd, 0)     // we added 0 tracks, 0 delta
+	})
+}
+
+func fuzzStruct(taken int, data []byte, dest interface{}) {
+	if len(data) == 0 {
+		return
+	}
+
+	r := seedRand(data)
+	v := reflect.ValueOf(dest)
+	for i := 0; i < v.Elem().NumField(); i++ {
+		if r.Float64() < 0.1 {
+			continue
+		}
+
+		take := int(r.Float64() * 12)
+		b := make([]byte, take)
+		for i := range b {
+			b[i] = data[(i+taken)%len(data)]
+		}
+		taken += take
+
+		switch f := v.Elem().Field(i); f.Kind() {
+		case reflect.Bool:
+			f.SetBool(b[0] < 128)
+		case reflect.String:
+			f.SetString(string(b))
+		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+			f.SetInt(int64(b[0]))
+		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+			f.SetUint(uint64(b[0]))
+		case reflect.Float32, reflect.Float64:
+			f.SetFloat(float64(b[0]))
+		case reflect.Struct:
+			fuzzStruct(taken, data, f.Addr().Interface())
+		}
+	}
+}
+
+func seedRand(seed []byte) *rand.Rand {
+	b := make([]byte, 8)
+	for i := range b {
+		b[i] = seed[i%len(seed)]
+	}
+	return rand.New(rand.NewSource(int64(binary.BigEndian.Uint64(b))))
+}

server/scanner/testdata/fuzz/FuzzScanner/50640a7a67794863f262b749f288aff8610f2cac65b7cf65b8708eb0ea104519

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("001")

server/scanner/testdata/fuzz/FuzzScanner/caf81e9797b19c76c1fc4dbf537d4d81f389524539f402d13aa01f93a65ac7e9

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("")