feat: add PawSQL docs examples and image CI

internal/pgwire/startup_test.go

@@ -0,0 +1,76 @@
+package pgwire
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"io"
+	"net"
+	"testing"
+	"time"
+)
+
+func TestStartupMessageReadsDatabase(t *testing.T) {
+	raw := startupBytes("analytics", "ruckstack")
+	message, err := ReadStartupMessage(bytes.NewReader(raw))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if message.Database != "analytics" {
+		t.Fatalf("Database = %q", message.Database)
+	}
+}
+
+func TestReadStartupMessageRejectsMissingDatabase(t *testing.T) {
+	_, err := ReadStartupMessage(bytes.NewReader(startupBytes("", "ruckstack")))
+	if !errors.Is(err, ErrMissingDatabase) {
+		t.Errorf("ReadStartupMessage() error = %v, want ErrMissingDatabase", err)
+	}
+}
+
+func TestReplayForwardsStartupAndUnderlyingStream(t *testing.T) {
+	reader, writer := io.Pipe()
+	defer reader.Close()
+	go func() {
+		_, _ = writer.Write([]byte("tail"))
+		_ = writer.Close()
+	}()
+	connection := &readOnlyConn{Reader: reader}
+	replayed := Replay(connection, []byte("startup"))
+	got, err := io.ReadAll(replayed)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(got) != "startuptail" {
+		t.Errorf("Replay() = %q", got)
+	}
+}
+
+func startupBytes(database, user string) []byte {
+	body := make([]byte, 4)
+	binary.BigEndian.PutUint32(body, startupProtocolVersion)
+	if database != "" {
+		body = append(body, "database"...)
+		body = append(body, 0)
+		body = append(body, database...)
+		body = append(body, 0)
+	}
+	body = append(body, "user"...)
+	body = append(body, 0)
+	body = append(body, user...)
+	body = append(body, 0, 0)
+	message := make([]byte, 4, 4+len(body))
+	message = append(message, body...)
+	binary.BigEndian.PutUint32(message, uint32(len(message)))
+	return message
+}
+
+type readOnlyConn struct{ io.Reader }
+
+func (c *readOnlyConn) Write([]byte) (int, error)        { return 0, io.ErrClosedPipe }
+func (c *readOnlyConn) Close() error                     { return nil }
+func (c *readOnlyConn) LocalAddr() net.Addr              { return nil }
+func (c *readOnlyConn) RemoteAddr() net.Addr             { return nil }
+func (c *readOnlyConn) SetDeadline(time.Time) error      { return nil }
+func (c *readOnlyConn) SetReadDeadline(time.Time) error  { return nil }
+func (c *readOnlyConn) SetWriteDeadline(time.Time) error { return nil }