Make Chunkreader an internal implementation detail

pgproto3/chunkreader_test.go

@@ -0,0 +1,116 @@
+package pgproto3
+
+import (
+	"bytes"
+	"math/rand"
+	"testing"
+)
+
+func TestChunkReaderNextDoesNotReadIfAlreadyBuffered(t *testing.T) {
+	server := &bytes.Buffer{}
+	r := newChunkReader(server, 4)
+
+	src := []byte{1, 2, 3, 4}
+	server.Write(src)
+
+	n1, err := r.Next(2)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if bytes.Compare(n1, src[0:2]) != 0 {
+		t.Fatalf("Expected read bytes to be %v, but they were %v", src[0:2], n1)
+	}
+
+	n2, err := r.Next(2)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if bytes.Compare(n2, src[2:4]) != 0 {
+		t.Fatalf("Expected read bytes to be %v, but they were %v", src[2:4], n2)
+	}
+
+	if bytes.Compare(r.buf, src) != 0 {
+		t.Fatalf("Expected r.buf to be %v, but it was %v", src, r.buf)
+	}
+	if r.rp != 4 {
+		t.Fatalf("Expected r.rp to be %v, but it was %v", 4, r.rp)
+	}
+	if r.wp != 4 {
+		t.Fatalf("Expected r.wp to be %v, but it was %v", 4, r.wp)
+	}
+}
+
+func TestChunkReaderNextExpandsBufAsNeeded(t *testing.T) {
+	server := &bytes.Buffer{}
+	r := newChunkReader(server, 4)
+
+	src := []byte{1, 2, 3, 4, 5, 6, 7, 8}
+	server.Write(src)
+
+	n1, err := r.Next(5)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if bytes.Compare(n1, src[0:5]) != 0 {
+		t.Fatalf("Expected read bytes to be %v, but they were %v", src[0:5], n1)
+	}
+	if len(r.buf) != 5 {
+		t.Fatalf("Expected len(r.buf) to be %v, but it was %v", 5, len(r.buf))
+	}
+}
+
+func TestChunkReaderDoesNotReuseBuf(t *testing.T) {
+	server := &bytes.Buffer{}
+	r := newChunkReader(server, 4)
+
+	src := []byte{1, 2, 3, 4, 5, 6, 7, 8}
+	server.Write(src)
+
+	n1, err := r.Next(4)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if bytes.Compare(n1, src[0:4]) != 0 {
+		t.Fatalf("Expected read bytes to be %v, but they were %v", src[0:4], n1)
+	}
+
+	n2, err := r.Next(4)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if bytes.Compare(n2, src[4:8]) != 0 {
+		t.Fatalf("Expected read bytes to be %v, but they were %v", src[4:8], n2)
+	}
+
+	if bytes.Compare(n1, src[0:4]) != 0 {
+		t.Fatalf("Expected KeepLast to prevent Next from overwriting buf, expected %v but it was %v", src[0:4], n1)
+	}
+}
+
+type randomReader struct {
+	rnd *rand.Rand
+}
+
+// Read reads a random number of random bytes.
+func (r *randomReader) Read(p []byte) (n int, err error) {
+	n = r.rnd.Intn(len(p) + 1)
+	return r.rnd.Read(p[:n])
+}
+
+func TestChunkReaderNextFuzz(t *testing.T) {
+	rr := &randomReader{rnd: rand.New(rand.NewSource(1))}
+	r := newChunkReader(rr, 8192)
+
+	randomSizes := rand.New(rand.NewSource(0))
+
+	for i := 0; i < 100000; i++ {
+		size := randomSizes.Intn(16384) + 1
+		buf, err := r.Next(size)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if len(buf) != size {
+			t.Fatalf("Expected to get %v bytes but got %v bytes", size, len(buf))
+		}
+	}
+}