tmux-tui-testing

# Enable mouse support in tmux (add to session or tmux.conf)
tmux set-option -t "$SESSION" mouse on

# Click at specific coordinates (x, y from top-left)
# Uses escape sequence: \e[<button;x;y;M for press, m for release
send_mouse_click() {
    local session="$1"
    local x="$2"
    local y="$3"

    # Send mouse press at (x, y) - button 0 = left click
    printf '\e[<0;%d;%dM' "$x" "$y" | tmux load-buffer -
    tmux paste-buffer -t "$session"

    # Send mouse release
    printf '\e[<0;%d;%dm' "$x" "$y" | tmux load-buffer -
    tmux paste-buffer -t "$session"
}

# Click at row 5, column 10
send_mouse_click "$SESSION" 10 5

# Alternative: Use send-keys with MouseDown/MouseUp (tmux 3.0+)
tmux send-keys -t "$SESSION" -M MouseDown1Pane 10 5
tmux send-keys -t "$SESSION" -M MouseUp1Pane 10 5

Clipboard Operations

# Copy text TO tmux buffer (for pasting into app)
echo "text to paste" | tmux load-buffer -

# Paste from tmux buffer into pane
tmux paste-buffer -t "$SESSION"

# Set buffer directly
tmux set-buffer "content to paste"

# Capture pane to buffer, then retrieve
tmux capture-pane -t "$SESSION" -b capture-buffer
tmux show-buffer -b capture-buffer

# For apps that use system clipboard, set DISPLAY for xclip/xsel
# or use pbcopy/pbpaste on macOS
tmux send-keys -t "$SESSION" "echo 'copied' | pbcopy" Enter

Multiple Panes

# Split window horizontally (top/bottom)
tmux split-window -t "$SESSION" -v

# Split window vertically (left/right)
tmux split-window -t "$SESSION" -h

# Address specific panes (0-indexed)
tmux send-keys -t "$SESSION:0.0" "left pane" Enter   # First pane
tmux send-keys -t "$SESSION:0.1" "right pane" Enter  # Second pane

# Resize panes
tmux resize-pane -t "$SESSION:0.0" -x 40  # Set width
tmux resize-pane -t "$SESSION:0.1" -y 10  # Set height

# Capture specific pane
tmux capture-pane -t "$SESSION:0.1" -p

# Select/focus a pane
tmux select-pane -t "$SESSION:0.1"

# List panes with their indices and dimensions
tmux list-panes -t "$SESSION" -F "#{pane_index}: #{pane_width}x#{pane_height}"

Pattern: Testing Split-Pane Apps

# Some TUIs use split layouts - test each pane independently
setup_split_test() {
    tmux new-session -d -s "$SESSION"
    tmux resize-window -t "$SESSION" -x 120 -y 40

    # Launch app that creates splits
    tmux send-keys -t "$SESSION" "./split-app" Enter
    sleep 1
}

verify_pane_content() {
    local pane="$1"
    local expected="$2"

    local content
    content=$(tmux capture-pane -t "$SESSION:0.$pane" -p)

    if echo "$content" | grep -q "$expected"; then
        echo "PASS: Pane $pane contains '$expected'"
        return 0
    else
        echo "FAIL: Pane $pane missing '$expected'"
        return 1
    fi
}

# Test left pane shows file list, right pane shows preview
verify_pane_content 0 "file1.txt"
verify_pane_content 1 "Preview:"

Pattern: Scrolling and Viewport

# Scroll up/down in pane (for apps with scrolling content)
tmux send-keys -t "$SESSION" PageUp
tmux send-keys -t "$SESSION" PageDown

# Enter copy mode to scroll (then exit)
tmux copy-mode -t "$SESSION"
tmux send-keys -t "$SESSION" -X scroll-up
tmux send-keys -t "$SESSION" -X scroll-down
tmux send-keys -t "$SESSION" q  # Exit copy mode

# Capture with scrollback (negative = lines above visible)
tmux capture-pane -t "$SESSION" -p -S -100 -E -1  # Last 100 lines of scrollback

# Capture everything (visible + all scrollback)
tmux capture-pane -t "$SESSION" -p -S - -E -

Pattern: Environment and Shell Setup

# Set environment variables before launching app
tmux send-keys -t "$SESSION" "export TERM=xterm-256color" Enter
tmux send-keys -t "$SESSION" "export NO_COLOR=1" Enter  # Disable colors for easier parsing
tmux send-keys -t "$SESSION" "export LC_ALL=en_US.UTF-8" Enter

# Start with clean shell
tmux send-keys -t "$SESSION" "env -i bash --norc --noprofile" Enter
tmux send-keys -t "$SESSION" "export TERM=xterm-256color" Enter

# Change directory
tmux send-keys -t "$SESSION" "cd /path/to/project" Enter

Pattern: Waiting for App Exit

wait_for_exit() {
    local session="$1"
    local timeout="${2:-30}"
    local elapsed=0

    while [ $elapsed -lt $timeout ]; do
        # Check if pane is showing shell prompt (app exited)
        if tmux capture-pane -t "$session" -p | grep -qE '^\$|^>|^%'; then
            return 0
        fi
        sleep 0.5
        elapsed=$((elapsed + 1))
    done
    return 1
}

# Run app and wait for it to finish
tmux send-keys -t "$SESSION" "./app --batch-mode" Enter
if wait_for_exit "$SESSION" 60; then
    echo "App completed"
else
    echo "App timed out"
    tmux send-keys -t "$SESSION" C-c  # Force quit
fi

Pattern: Capture with Line Numbers

# Useful for debugging - see exactly which line contains what
capture_with_lines() {
    local session="$1"
    tmux capture-pane -t "$session" -p | nl -ba
}

# Assert content at specific line
assert_line() {
    local session="$1"
    local line_num="$2"
    local expected="$3"

    local actual
    actual=$(tmux capture-pane -t "$session" -p | sed -n "${line_num}p")

    if [ "$actual" = "$expected" ]; then
        echo "PASS: Line $line_num matches"
        return 0
    else
        echo "FAIL: Line $line_num"
        echo "  Expected: '$expected'"
        echo "  Actual:   '$actual'"
        return 1
    fi
}

# Check that line 3 shows the header
assert_line "$SESSION" 3 "=== My App v1.0 ==="