Show square brackets in the neoirc-cli message window as written (closes #233)

The message window has colour tags on, so tview read square-bracket
text in nicks, channel names, reasons, topics and message text as
tags. It dropped that text or changed the colour of the rest of the
line.

A new escape in internal/cli/ui.go writes each "[" as "[[:]", and
app.go applies it to every part of a line that comes from the user or
the server. tview.Escape is not used: it misses bracket pairs holding
symbols such as "|", and tags with a URL.

Lines for other server commands now show the command, such as
"[MODE]", which tview had read as a tag.

Model: opus-5-5

internal/cli/app_internal_test.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"testing"
 	"time"
+	"unicode/utf8"
 
 	"github.com/gdamore/tcell/v2"
 	api "sneak.berlin/go/neoirc/internal/cli/api"
@@ -845,6 +846,109 @@ func TestOwnEventFromOtherClient(t *testing.T) {
 	}
 }
 
+// TestBracketsInMessageWindow checks that each kind of line drawn
+// from a server event shows nicks, texts, reasons and topics
+// holding square brackets as written.
+func TestBracketsInMessageWindow(t *testing.T) {
+	t.Parallel()
+
+	// Every event is sent to the channel and has a body of one line.
+	tests := []struct {
+		name    string
+		command string
+		from    string
+		body    string
+		// Whether the line goes to the channel's window rather than
+		// the status window, which is the one shown at start.
+		inChannel bool
+		// How the line ends, after the timestamps.
+		want string
+	}{
+		{
+			name: "message", command: irc.CmdPrivmsg, inChannel: true,
+			from: "bob[|[]", body: "x[^[] [:::y|z] [red]",
+			want: "<bob[|[]> x[^[] [:::y|z] [red]",
+		},
+		{
+			name: "joined", command: irc.CmdJoin, from: "x[^[]", inChannel: true,
+			want: "*** x[^[] has joined #chan",
+		},
+		{
+			name: "left", command: irc.CmdPart, inChannel: true,
+			from: "erin[away]", body: "[:::y|z]",
+			want: "*** erin[away] has left #chan ([:::y|z])",
+		},
+		{
+			name: "topic", command: irc.CmdTopic, inChannel: true,
+			from: "dave[afk]", body: "[red]news",
+			want: "*** dave[afk] set topic: [red]news",
+		},
+		{
+			name: "quit", command: irc.CmdQuit, from: "carol[x]", body: "bye [red]",
+			want: "*** carol[x] has quit (bye [red])",
+		},
+		{
+			name: "nick change", command: irc.CmdNick, from: "erin[m]", body: "erin[x]",
+			want: "*** erin[m] is now known as erin[x]",
+		},
+		{
+			name: "notice", command: irc.CmdNotice, from: "bob[]", body: "[::b]note",
+			want: "--bob[]-- [::b]note",
+		},
+		{
+			name: "other command", command: irc.CmdMode, body: "+v dave[afk]",
+			want: "[MODE] +v dave[afk]",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			t.Parallel()
+
+			app := &App{ui: NewUI(), nick: testNick}
+			screen := runUI(t, app.ui)
+
+			if test.inChannel {
+				app.ui.SwitchToBuffer(testChannel)
+			}
+
+			app.handleServerMessage(&api.Message{
+				Command: test.command, From: test.from, To: testChannel,
+				Body: []string{test.body},
+			})
+
+			got, _ := shownLine(app.ui, screen)
+			if !strings.HasSuffix(got, test.want) {
+				t.Fatalf("message window shows %q, want it to end %q", got, test.want)
+			}
+		})
+	}
+}
+
+// TestColourTagInMessage checks that a colour tag in a message
+// shows as written and leaves the message text white, as the
+// client draws it.
+func TestColourTagInMessage(t *testing.T) {
+	t.Parallel()
+
+	const want = "<bob> [red]x"
+
+	app := &App{ui: NewUI(), nick: testNick}
+	screen := runUI(t, app.ui)
+	app.ui.SwitchToBuffer(testChannel)
+
+	app.handleServerMessage(&api.Message{
+		Command: irc.CmdPrivmsg, From: testOtherNick, To: testChannel,
+		Body: []string{"[red]x"},
+	})
+
+	got, colour := shownLine(app.ui, screen)
+	if !strings.HasSuffix(got, want) || colour != tcell.ColorWhite {
+		t.Fatalf("message window shows %q, its last character in %v; "+
+			"want it to end %q, in white", got, colour, want)
+	}
+}
+
 // bufferState returns the number of lines in the named
 // buffer and how many of them are unread.
 func bufferState(ui *UI, name string) (int, int) {
@@ -872,6 +976,39 @@ func statusBarText(ui *UI) string {
 	return text
 }
 
+// shownLine returns the first line of the message window as the
+// screen shows it, without the blanks after it, and the colour of
+// its last character.
+func shownLine(
+	ui *UI, screen tcell.SimulationScreen,
+) (string, tcell.Color) {
+	var (
+		text   string
+		colour tcell.Color
+	)
+
+	ui.app.QueueUpdate(func() {
+		cells, width, _ := screen.GetContents()
+
+		var row strings.Builder
+
+		for _, cell := range cells[:width] {
+			row.WriteString(string(cell.Runes))
+		}
+
+		text = strings.TrimRight(row.String(), " ")
+		if text == "" {
+			return
+		}
+
+		// Each character in these tests takes one cell.
+		last := cells[utf8.RuneCountInString(text)-1]
+		colour, _, _ = last.Style.Decompose()
+	})
+
+	return text, colour
+}
+
 // handledLines makes app.ui pass each typed line to
 // app.handleInput, as Run does, and returns a channel that
 // receives each line once it has been handled.
@@ -964,11 +1101,15 @@ func waitPoll(t *testing.T, polled <-chan struct{}, server string) {
 	}
 }
 
-// runUI runs ui on a simulated screen until the test ends.
-func runUI(t *testing.T, ui *UI) {
+// runUI runs ui on a simulated screen until the test ends, and
+// returns the screen.
+//
+//nolint:ireturn // tcell has no exported type for the screen
+func runUI(t *testing.T, ui *UI) tcell.SimulationScreen {
 	t.Helper()
 
-	ui.app.SetScreen(tcell.NewSimulationScreen(""))
+	screen := tcell.NewSimulationScreen("")
+	ui.app.SetScreen(screen)
 
 	// One slot, so that Run's goroutine can end even after the
 	// cleanup below has stopped waiting for it.
@@ -988,4 +1129,6 @@ func runUI(t *testing.T, ui *UI) {
 			t.Error("the UI did not stop: its event loop stopped responding")
 		}
 	})
+
+	return screen
 }