Rewrite magic source

pkg/core/readbuffer_test.go

@@ -0,0 +1,64 @@
+package core
+
+import (
+	"bytes"
+	"io"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestReadSeeker(t *testing.T) {
+	b := []byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
+	buf := bytes.NewReader(b)
+
+	rd := NewReadBuffer(buf)
+	rd.BufferSize = ProbeSize
+
+	// 1. Read to buffer
+	b = make([]byte, 3)
+	n, err := rd.Read(b)
+	require.Nil(t, err)
+	require.Equal(t, []byte{0, 1, 2}, b[:n])
+
+	// 2. Seek to start
+	_, err = rd.Seek(0, io.SeekStart)
+	require.Nil(t, err)
+
+	// 3. Read from buffer
+	b = make([]byte, 2)
+	n, err = rd.Read(b)
+	require.Nil(t, err)
+	require.Equal(t, []byte{0, 1}, b[:n])
+
+	// 4. Read from buffer
+	n, err = rd.Read(b)
+	require.Nil(t, err)
+	require.Equal(t, []byte{2}, b[:n])
+
+	// 5. Read to buffer
+	n, err = rd.Read(b)
+	require.Nil(t, err)
+	require.Equal(t, []byte{3, 4}, b[:n])
+
+	// 6. Seek to start
+	_, err = rd.Seek(0, io.SeekStart)
+	require.Nil(t, err)
+
+	// 7. Disable buffer
+	rd.BufferSize = -1
+
+	// 8. Read from buffer
+	b = make([]byte, 10)
+	n, err = rd.Read(b)
+	require.Nil(t, err)
+	require.Equal(t, []byte{0, 1, 2, 3, 4}, b[:n])
+
+	// 9. Direct read
+	n, err = rd.Read(b)
+	require.Nil(t, err)
+	require.Equal(t, []byte{5, 6, 7, 8, 9}, b[:n])
+
+	// 10. Check buffer empty
+	require.Nil(t, rd.buf)
+}