/pine-backtester

name: pine-backtester
description: Implements comprehensive backtesting and performance metrics. Use when adding trade analysis, equity curves, or statistical validation.
allowed-tools: Read, Edit, Grep, Glob

Pine Script Backtester

Specialized in adding comprehensive testing and validation capabilities to Pine Script indicators and strategies.

Core Responsibilities

Strategy Performance Metrics

• Win rate and profit factor
• Maximum drawdown analysis
• Sharpe and Sortino ratios
• Risk-adjusted returns
• Trade distribution analysis

Indicator Accuracy Testing

• Signal accuracy measurements
• False positive/negative rates
• Lag analysis
• Divergence detection accuracy
• Multi-timeframe validation

Statistical Analysis

• Monte Carlo simulations
• Walk-forward analysis
• Confidence intervals
• Statistical significance tests
• Correlation analysis

Pine Script v6 2025 Backtesting Features

Enhanced Reporting (August 2025: 40,960 char strings)

Now possible: comprehensive multi-section reports:

// Build detailed performance report (up to 40K chars!)
var string fullReport = ""
fullReport := "═══════════════════════════════════════════\n"
fullReport += "           COMPREHENSIVE BACKTEST REPORT    \n"
fullReport += "═══════════════════════════════════════════\n\n"
fullReport += "PERFORMANCE SUMMARY\n"
fullReport += "───────────────────\n"
fullReport += "Win Rate: " + str.tostring(winRate, "#.##") + "%\n"
fullReport += "Profit Factor: " + str.tostring(pf, "#.##") + "\n"
fullReport += "Sharpe Ratio: " + str.tostring(sharpe, "#.##") + "\n\n"
fullReport += "TRADE DISTRIBUTION\n"
fullReport += "───────────────────\n"
// ... Can include much more detailed analysis

Use `for...in` for Trade Arrays (March 2025)

The preferred way to iterate over trade data arrays:

// ✅ BEST: Use for...in for arrays (safe, clean)
for tradeReturn in tradeReturns
    // Process each return directly

// ✅ BEST: With index when needed
for [i, tradeReturn] in tradeReturns
    // Have both index and value

// ❌ AVOID: Traditional for with dynamic boundary
for i = 0 to array.size(tradeReturns) - 1
    array.push(newArray, processedValue)  // Can infinite loop!

// ✅ FALLBACK: If traditional for needed, cache boundary
arrSize = array.size(tradeReturns)
for i = 0 to arrSize - 1
    // Safe processing

Conditional Backtest Settings (July 2025)

Use `active` parameter to show relevant settings:

showAdvancedMetrics = input.bool(false, "Show Advanced Metrics", group="Backtest")
sharpeRiskFreeRate = input.float(0.02, "Risk-Free Rate",
    group="Backtest",
    active=showAdvancedMetrics,  // Only show when advanced enabled
    tooltip="Annual risk-free rate for Sharpe calculation")

Visual Line Styles (September 2025)

Differentiate backtest visualization with line styles:

// Primary metrics: solid
plot(strategy.equity, "Equity", color.blue, linestyle=plot.linestyle_solid)
// Benchmarks: dashed
plot(benchmarkEquity, "Benchmark", color.gray, linestyle=plot.linestyle_dashed)
// Projections: dotted
plot(projectedEquity, "Projected", color.yellow, linestyle=plot.linestyle_dotted)

⚠️ UDT-First Trade Tracking

**For comprehensive trade analysis, use UDTs to track individual trades.**

Trade UDT Pattern

// Define Trade UDT for detailed tracking
type Trade
    // Time coordinates (for historical analysis)
    int entryTime
    int exitTime
    int entryBar
    int exitBar

    // Trade data
    float entryPrice
    float exitPrice
    float positionSize
    bool isLong
    string exitReason

    // Calculated metrics
    float pnl = 0.0
    float pnlPercent = 0.0
    int duration = 0

    // Visualization (optional)
    line tradeLine = na
    label entryLabel = na
    label exitLabel = na

// Methods for trade analysis
method calculate(Trade this) =>
    this.duration := this.exitBar - this.entryBar
    if this.isLong
        this.pnl := (this.exitPrice - this.entryPrice) * this.positionSize
        this.pnlPercent := ((this.exitPrice - this.entryPrice) / this.entryPrice) * 100
    else
        this.pnl := (this.entryPrice - this.exitPrice) * this.positionSize
        this.pnlPercent := ((this.entryPrice - this.exitPrice) / this.entryPrice) * 100

method draw(Trade this, color winColor, color loseColor) =>
    tradeColor = this.pnl >= 0 ? winColor : loseColor
    // Use xloc.bar_time for unlimited lookback!
    this.tradeLine := line.new(this.entryTime, this.entryPrice,
         this.exitTime, this.exitPrice,
         xloc=xloc.bar_time, color=tradeColor, width=2)

// Storage
var array<Trade> completedTrades = array.new<Trade>()
var Trade currentTrade = na

Trade Analysis with for...in

// Analyze all trades using for...in
if barstate.islastconfirmedhistory
    totalPnl = 0.0
    wins = 0
    losses = 0
    totalDuration = 0

    for trade in completedTrades
        totalPnl += trade.pnl
        if trade.pnl >= 0
            wins += 1
        else
            losses += 1
        totalDuration += trade.duration

    winRate = array.size(completedTrades) > 0 ? (wins / array.size(completedTrades)) * 100 : 0
    avgDuration = array.size(completedTrades) > 0 ? totalDuration / array.size(completedTrades) : 0

Trade Distribution with UDT Arrays

// Categorize trades by exit reason
var array<Trade> stopLossTrades = array.new<Trade>()
var array<Trade> takeProfitTrades = array.new<Trade>()
var array<Trade> timeoutTrades = array.new<Trade>()

// When trade closes, categorize it
if tradeJustClosed
    if currentTrade.exitReason == "SL"
        array.push(stopLossTrades, currentTrade)
    else if currentTrade.exitReason == "TP"
        array.push(takeProfitTrades, currentTrade)
    else
        array.push(timeoutTrades, currentTrade)

// Analyze by category
if barstate.islast
    slCount = array.size(stopLossTrades)
    tpCount = array.size(takeProfitTrades)
    // ... di