隨記

說明

Methods must not exceed a cyclomatic complexity of 10. Classes must not exceed a total complexity of 50.

Cyclomatic complexity counts the number of independent paths through a method. Higher values mean more branches, harder testing, and higher bug probability.

為什麼重要

  • Testability — each path needs a test case; complexity 10 = minimum 10 test paths
  • Bug density — methods with complexity > 10 have 2-3x more defects
  • Readability — deeply nested logic is hard to follow

Enforcement

Rule: java:S1192 — Cyclomatic Complexity Quality Gate: new_coverage >= 80% AND new_duplicated_lines_density < 3%

正例

public OrderStatus getStatus(Order order) {
    if (order.isCancelled()) {
        return OrderStatus.CANCELLED;
    }
    if (order.isDelivered()) {
        return OrderStatus.DELIVERED;
    }
    return OrderStatus.IN_PROGRESS;
}

反例

public OrderStatus getStatus(Order order) {
    if (order != null) {
        if (!order.isCancelled()) {
            if (order.isDelivered()) {
                if (order.getDeliveryDate() != null) {
                    if (order.getDeliveryDate().isBefore(LocalDate.now())) {
                        // ❌ deeply nested, complexity = 6 just for this block
                    }
                }
            }
        }
    }
}