Function TestDB_WriteTo_and_Overwrite

db_test.go:800–903

TestDB_WriteTo_and_Overwrite verifies that `(tx *Tx) WriteTo` can still work even the underlying file is overwritten between the time a read-only transaction is created and the time the file is actually opened

(t *testing.T)

// work even the underlying file is overwritten between the time a read-only
// transaction is created and the time the file is actually opened
func TestDB_WriteTo_and_Overwrite(t *testing.T) {
	testCases := []struct {
		name      string
		writeFlag int
	}{
		{
			name:      "writeFlag not set",
			writeFlag: 0,
		},
		/* syscall.O_DIRECT not supported on some platforms, i.e. Windows and MacOS
		{
			name:      "writeFlag set",
			writeFlag: syscall.O_DIRECT,
		},*/
	}

	fRead := func(db *bolt.DB, bucketName []byte) map[string]string {
		data := make(map[string]string)
		_ = db.View(func(tx *bolt.Tx) error {
			b := tx.Bucket(bucketName)
			berr := b.ForEach(func(k, v []byte) error {
				data[string(k)] = string(v)
				return nil
			})
			require.NoError(t, berr)
			return nil
		})
		return data
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			db := btesting.MustCreateDBWithOption(t, &bolt.Options{
				PageSize: 4096,
			})
			filePathOfDb := db.Path()

			var (
				bucketName   = []byte("data")
				dataExpected map[string]string
				dataActual   map[string]string
			)

			t.Log("Populate some data")
			err := db.Update(func(tx *bolt.Tx) error {
				b, berr := tx.CreateBucket(bucketName)
				if berr != nil {
					return berr
				}
				for k := 0; k < 10; k++ {
					key, value := fmt.Sprintf("key_%d", rand.Intn(10)), fmt.Sprintf("value_%d", rand.Intn(100))
					if perr := b.Put([]byte(key), []byte(value)); perr != nil {
						return perr
					}
				}
				return nil
			})
			require.NoError(t, err)