Send peers the IRC listener user's QUIT reason (closes #216)

handleQuit now records the reason on the connection, and cleanup
passes it to BroadcastQuit, the same service call the HTTP API's
QUIT uses. A QUIT without a reason still gives Client quit. A
connection that ends without a QUIT still gives Connection closed.

The relay test that expected Connection closed for a bare QUIT now
expects Client quit.

Model: opus-5-5

internal/ircserver/server_test.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"context"
 	"database/sql"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"log/slog"
@@ -24,6 +25,7 @@ import (
 	"sneak.berlin/go/neoirc/internal/globals"
 	"sneak.berlin/go/neoirc/internal/ircserver"
 	"sneak.berlin/go/neoirc/internal/logger"
+	"sneak.berlin/go/neoirc/pkg/irc"
 
 	_ "modernc.org/sqlite"
 )
@@ -873,6 +875,112 @@ func TestQuit(t *testing.T) {
 	assertContains(t, lines, "goodbye", "QUIT reason")
 }
 
+// TestQuitReasonReachesPeers checks the reason that an IRC
+// listener user's channel peers see in its QUIT, on both the
+// IRC listener and the HTTP API. It is the reason the user
+// gave, Client quit for a QUIT without one, or Connection
+// closed when the connection ends without a QUIT.
+func TestQuitReasonReachesPeers(t *testing.T) {
+	t.Parallel()
+
+	for _, step := range []struct {
+		name, quit, want string
+	}{
+		{"QUIT with a reason", "QUIT :gone home", "gone home"},
+		{"QUIT without a reason", irc.CmdQuit, "Client quit"},
+		{"connection closed without QUIT", "", "Connection closed"},
+	} {
+		t.Run(step.name, func(t *testing.T) {
+			t.Parallel()
+
+			ircLine, apiBody := quitSeenByPeers(t, step.quit)
+
+			want := ":quitter!quitter@* QUIT :Quit: " + step.want
+			if ircLine != want {
+				t.Errorf("IRC peer got %q, want %q", ircLine, want)
+			}
+
+			if len(apiBody) != 1 || apiBody[0] != step.want {
+				t.Errorf("HTTP API peer got %q, want [%q]", apiBody, step.want)
+			}
+		})
+	}
+}
+
+// quitSeenByPeers starts a server on which quitter, ircpeer on
+// the IRC listener and apipeer on the HTTP API share a channel.
+// quitter sends the line quit, or closes its connection when
+// quit is empty. It returns the QUIT line ircpeer is sent and
+// the body of the QUIT apipeer is sent.
+func quitSeenByPeers(t *testing.T, quit string) (string, []string) {
+	t.Helper()
+
+	env := newTestEnv(t)
+	ctx := t.Context()
+
+	ircPeer := env.dial(t)
+	ircPeer.register("ircpeer")
+	ircPeer.joinAndDrain("#bye")
+
+	apiPeerID, apiPeerClientID, _, err := env.database.CreateSession(
+		ctx, "apipeer", "apipeer", "", "",
+	)
+	if err != nil {
+		t.Fatalf("create peer session: %v", err)
+	}
+
+	channelID, err := env.database.GetChannelByName(ctx, "#bye")
+	if err != nil {
+		t.Fatalf("get channel: %v", err)
+	}
+
+	err = env.database.JoinChannel(ctx, channelID, apiPeerID)
+	if err != nil {
+		t.Fatalf("join peer: %v", err)
+	}
+
+	quitter := env.dial(t)
+	quitter.register("quitter")
+	quitter.joinAndDrain("#bye")
+
+	if quit == "" {
+		err = quitter.conn.Close()
+		if err != nil {
+			t.Fatalf("close: %v", err)
+		}
+	} else {
+		quitter.send(quit)
+	}
+
+	lines := ircPeer.readUntil(func(l string) bool {
+		return strings.Contains(l, " QUIT ")
+	})
+
+	// The QUIT is queued to both peers at once, so apipeer has
+	// it by now.
+	msgs, _, err := env.database.PollMessages(ctx, apiPeerClientID, 0, 0)
+	if err != nil {
+		t.Fatalf("poll peer: %v", err)
+	}
+
+	for _, msg := range msgs {
+		if msg.Command == irc.CmdQuit && msg.From == "quitter" {
+			var body []string
+
+			err = json.Unmarshal(msg.Body, &body)
+			if err != nil {
+				t.Fatalf("decode QUIT body %s: %v", msg.Body, err)
+			}
+
+			return lines[len(lines)-1], body
+		}
+	}
+
+	t.Fatalf("apipeer was not sent the QUIT: %v", msgs)
+
+	return "", nil
+}
+
 // TestStopEndsSessions checks that stopping the server ends
 // a registered connection's session before Stop returns, as
 // closing the connection does: the session, its client and