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Extract hardcoded discount description strings to named constants #31

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9158a59
Initial plan
Copilot Feb 20, 2026
5419d3a
Clean up magic strings in Python, Java, C#, and TypeScript implementa…
Copilot Feb 20, 2026
cccbd17
Clean up magic strings in Go, Ruby, Elixir, Lisp, Kotlin, PHP, Swift,…
Copilot Feb 20, 2026
1fa30ed
Fix spacing consistency in Go and Common Lisp discount descriptions
Copilot Feb 20, 2026
4a7e2b8
Fix Go and Common Lisp formatting for percent off suffix
Copilot Feb 20, 2026
93bc23d
Add leading space to percent off suffix constants for consistent form…
Copilot Feb 20, 2026
af4499c
Finalize magic string cleanup across all implementations
Copilot Feb 20, 2026
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1 change: 1 addition & 0 deletions _codeql_detected_source_root
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@@ -0,0 +1 @@
.
8 changes: 6 additions & 2 deletions common-lisp/source/shopping-cart.lisp
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Expand Up @@ -2,6 +2,10 @@

(in-package :supermarket-receipt)

;; Discount description constants
(defconstant +three-for-two-description+ "3 for 2")
(defconstant +percent-off-suffix+ " % off")

(defclass shopping-cart ()
((items :initform nil
:type list
Expand Down Expand Up @@ -56,12 +60,12 @@
(* (mod floored-quantity 3) a-unit-price)))))
(setf a-discount (make-instance 'discount
:product a-product
:description "3 for 2"
:description +three-for-two-description+
:amount (- discount-amount)))))
(when (eq the-offer-type 'ten-percent-discount)
(setf a-discount (make-instance 'discount
:product a-product
:description (format nil "~S % off" (offer-argument offer-for-product))
:description (format nil "~A~A" (offer-argument offer-for-product) +percent-off-suffix+)
:amount (/ (* (- a-quantity) a-unit-price (offer-argument offer-for-product)) 100.0))))
(when (and (eq the-offer-type 'five-for-amount)
(>= floored-quantity 5))
Expand Down
8 changes: 6 additions & 2 deletions cpp/src/ShoppingCart.cpp
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@@ -1,5 +1,9 @@
#include "ShoppingCart.h"

// Discount description constants
static const std::string THREE_FOR_TWO_DESCRIPTION = "3 for 2";
static const std::string PERCENT_OFF_SUFFIX = " % off";

void addItemQuantity(const Product& product, double quantity);

std::vector<ProductQuantity> ShoppingCart::getItems() const {
Expand Down Expand Up @@ -49,10 +53,10 @@ void ShoppingCart::handleOffers(Receipt& receipt, std::map<Product, Offer> offer
int numberOfXs = quantityAsInt / x;
if (offer.getOfferType() == SpecialOfferType::ThreeForTwo && quantityAsInt > 2) {
double discountAmount = quantity * unitPrice - ((numberOfXs * 2 * unitPrice) + quantityAsInt % 3 * unitPrice);
discount = new Discount("3 for 2", -discountAmount, product);
discount = new Discount(THREE_FOR_TWO_DESCRIPTION, -discountAmount, product);
}
if (offer.getOfferType() == SpecialOfferType::TenPercentDiscount) {
discount = new Discount(std::to_string(offer.getArgument()) + "% off", -quantity * unitPrice * offer.getArgument() / 100.0, product);
discount = new Discount(std::to_string(offer.getArgument()) + PERCENT_OFF_SUFFIX, -quantity * unitPrice * offer.getArgument() / 100.0, product);
}
if (offer.getOfferType() == SpecialOfferType::FiveForAmount && quantityAsInt >= 5) {
double discountTotal = unitPrice * quantity - (offer.getArgument() * numberOfXs + quantityAsInt % 5 * unitPrice);
Expand Down
8 changes: 6 additions & 2 deletions csharp-ms/SupermarketReceipt/ShoppingCart.cs
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Expand Up @@ -4,6 +4,10 @@ namespace SupermarketReceipt
{
public class ShoppingCart
{
// Discount description constants
private const string THREE_FOR_TWO_DESCRIPTION = "3 for 2";
private const string PERCENT_OFF_SUFFIX = " % off";

private readonly List<ProductQuantity> _items = new List<ProductQuantity>();
private readonly Dictionary<Product, double> _productQuantities = new Dictionary<Product, double>();

Expand Down Expand Up @@ -65,10 +69,10 @@ public void HandleOffers(Receipt receipt, Dictionary<Product, Offer> offers, Sup
if (offer.OfferType == SpecialOfferType.ThreeForTwo && quantityAsInt > 2)
{
var discountAmount = quantity * unitPrice - (numberOfXs * 2 * unitPrice + quantityAsInt % 3 * unitPrice);
discount = new Discount(p, "3 for 2", -discountAmount);
discount = new Discount(p, THREE_FOR_TWO_DESCRIPTION, -discountAmount);
}

if (offer.OfferType == SpecialOfferType.TenPercentDiscount) discount = new Discount(p, offer.Argument + "% off", -quantity * unitPrice * offer.Argument / 100.0);
if (offer.OfferType == SpecialOfferType.TenPercentDiscount) discount = new Discount(p, offer.Argument + PERCENT_OFF_SUFFIX, -quantity * unitPrice * offer.Argument / 100.0);
if (offer.OfferType == SpecialOfferType.FiveForAmount && quantityAsInt >= 5)
{
var discountTotal = unitPrice * quantity - (offer.Argument * numberOfXs + quantityAsInt % 5 * unitPrice);
Expand Down
8 changes: 6 additions & 2 deletions csharp/SupermarketReceipt/ShoppingCart.cs
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Expand Up @@ -5,6 +5,10 @@ namespace SupermarketReceipt
{
public class ShoppingCart
{
// Discount description constants
private const string THREE_FOR_TWO_DESCRIPTION = "3 for 2";
private const string PERCENT_OFF_SUFFIX = " % off";

private readonly List<ProductQuantity> _items = new List<ProductQuantity>();
private readonly Dictionary<Product, double> _productQuantities = new Dictionary<Product, double>();
private static readonly CultureInfo Culture = CultureInfo.CreateSpecificCulture("en-GB");
Expand Down Expand Up @@ -67,10 +71,10 @@ public void HandleOffers(Receipt receipt, Dictionary<Product, Offer> offers, Sup
if (offer.OfferType == SpecialOfferType.ThreeForTwo && quantityAsInt > 2)
{
var discountAmount = quantity * unitPrice - (numberOfXs * 2 * unitPrice + quantityAsInt % 3 * unitPrice);
discount = new Discount(p, "3 for 2", -discountAmount);
discount = new Discount(p, THREE_FOR_TWO_DESCRIPTION, -discountAmount);
}

if (offer.OfferType == SpecialOfferType.TenPercentDiscount) discount = new Discount(p, offer.Argument + "% off", -quantity * unitPrice * offer.Argument / 100.0);
if (offer.OfferType == SpecialOfferType.TenPercentDiscount) discount = new Discount(p, offer.Argument + PERCENT_OFF_SUFFIX, -quantity * unitPrice * offer.Argument / 100.0);
if (offer.OfferType == SpecialOfferType.FiveForAmount && quantityAsInt >= 5)
{
var discountTotal = unitPrice * quantity - (offer.Argument * numberOfXs + quantityAsInt % 5 * unitPrice);
Expand Down
8 changes: 6 additions & 2 deletions elixir/lib/supermarket/model/shopping_cart.ex
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Expand Up @@ -5,6 +5,10 @@ defmodule Supermarket.Model.ShoppingCart do
alias Supermarket.Model.Receipt
alias Supermarket.Model.SupermarketCatalog

# Discount description constants
@three_for_two_description "3 for 2"
@percent_off_suffix " % off"

defstruct [:items, :product_quantities]

def new, do: %__MODULE__{items: [], product_quantities: %{}}
Expand Down Expand Up @@ -70,12 +74,12 @@ defmodule Supermarket.Model.ShoppingCart do
quantity * unit_price -
(number_of_xs * 2 * unit_price + Integer.mod(quantity_as_int, 3) * unit_price)

Discount.new(p, "3 for 2", -discount_amount)
Discount.new(p, @three_for_two_description, -discount_amount)

offer.offer_type == :ten_percent_discount ->
Discount.new(
p,
"#{offer.argument}% off",
"#{offer.argument}#{@percent_off_suffix}",
-quantity * unit_price * offer.argument / 100.0
)

Expand Down
10 changes: 8 additions & 2 deletions go/supermarket/shopping_cart.go
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Expand Up @@ -5,6 +5,12 @@ import (
"math"
)

// Discount description constants
const (
threeForTwoDescription = "3 for 2"
percentOffSuffix = " % off"
)

type ProductQuantity struct {
product Product
quantity float64
Expand Down Expand Up @@ -62,10 +68,10 @@ func (c *ShoppingCart) handleOffers(receipt *Receipt, offers map[Product]Special
var numberOfXs int = quantityAsInt / x;
if offer.offerType == ThreeForTwo && quantityAsInt > 2 {
var discountAmount = quantity * unitPrice - (float64(numberOfXs * 2) * unitPrice + float64(quantityAsInt % 3) * unitPrice)
discount = &Discount{product: p, description: "3 for 2", discountAmount: -discountAmount}
discount = &Discount{product: p, description: threeForTwoDescription, discountAmount: -discountAmount}
}
if offer.offerType == TenPercentDiscount {
discount = &Discount{product: p, description: fmt.Sprintf("%.0f %% off", offer.argument), discountAmount: -quantity * unitPrice * offer.argument / 100.0}
discount = &Discount{product: p, description: fmt.Sprintf("%.0f%s", offer.argument, percentOffSuffix), discountAmount: -quantity * unitPrice * offer.argument / 100.0}
}
if offer.offerType == FiveForAmount && quantityAsInt >= 5 {
var discountTotal = unitPrice * quantity - (offer.argument * float64(numberOfXs) + float64(quantityAsInt % 5) * unitPrice)
Expand Down
8 changes: 6 additions & 2 deletions java/src/main/java/dojo/supermarket/model/ShoppingCart.java
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Expand Up @@ -8,6 +8,10 @@

public class ShoppingCart {

// Discount description constants
private static final String THREE_FOR_TWO_DESCRIPTION = "3 for 2";
private static final String PERCENT_OFF_SUFFIX = " % off";

private final List<ProductQuantity> items = new ArrayList<>();
private final Map<Product, Double> productQuantities = new HashMap<>();

Expand Down Expand Up @@ -58,10 +62,10 @@ void handleOffers(Receipt receipt, Map<Product, Offer> offers, SupermarketCatalo
int numberOfXs = quantityAsInt / x;
if (offer.offerType == SpecialOfferType.THREE_FOR_TWO && quantityAsInt > 2) {
double discountAmount = quantity * unitPrice - ((numberOfXs * 2 * unitPrice) + quantityAsInt % 3 * unitPrice);
discount = new Discount(p, "3 for 2", -discountAmount);
discount = new Discount(p, THREE_FOR_TWO_DESCRIPTION, -discountAmount);
}
if (offer.offerType == SpecialOfferType.TEN_PERCENT_DISCOUNT) {
discount = new Discount(p, offer.argument + "% off", -quantity * unitPrice * offer.argument / 100.0);
discount = new Discount(p, offer.argument + PERCENT_OFF_SUFFIX, -quantity * unitPrice * offer.argument / 100.0);
}
if (offer.offerType == SpecialOfferType.FIVE_FOR_AMOUNT && quantityAsInt >= 5) {
double discountTotal = unitPrice * quantity - (offer.argument * numberOfXs + quantityAsInt % 5 * unitPrice);
Expand Down
10 changes: 8 additions & 2 deletions kotlin/src/main/kotlin/supermarket/model/ShoppingCart.kt
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Expand Up @@ -5,6 +5,12 @@ import java.util.HashMap

class ShoppingCart {

// Discount description constants
companion object {
private const val THREE_FOR_TWO_DESCRIPTION = "3 for 2"
private const val PERCENT_OFF_SUFFIX = " % off"
}

private val items = ArrayList<ProductQuantity>()
internal var productQuantities: MutableMap<Product, Double> = HashMap()

Expand Down Expand Up @@ -59,11 +65,11 @@ class ShoppingCart {
if (offer.offerType === SpecialOfferType.ThreeForTwo && quantityAsInt > 2) {
val discountAmount =
quantity * unitPrice - (numberOfXs.toDouble() * 2.0 * unitPrice + quantityAsInt % 3 * unitPrice)
discount = Discount(p, "3 for 2", discountAmount)
discount = Discount(p, THREE_FOR_TWO_DESCRIPTION, discountAmount)
}
if (offer.offerType === SpecialOfferType.TenPercentDiscount) {
discount =
Discount(p, offer.argument.toString() + "% off", quantity * unitPrice * offer.argument / 100.0)
Discount(p, offer.argument.toString() + PERCENT_OFF_SUFFIX, quantity * unitPrice * offer.argument / 100.0)
}
if (offer.offerType === SpecialOfferType.FiveForAmount && quantityAsInt >= 5) {
val discountTotal =
Expand Down
8 changes: 6 additions & 2 deletions php/src/Model/ShoppingCart.php
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Expand Up @@ -8,6 +8,10 @@

class ShoppingCart
{
// Discount description constants
private const THREE_FOR_TWO_DESCRIPTION = '3 for 2';
private const PERCENT_OFF_SUFFIX = ' % off';

/**
* @var ProductQuantity[]
*/
Expand Down Expand Up @@ -81,13 +85,13 @@ public function handleOffers(Receipt $receipt, Map $offers, SupermarketCatalog $
$numberOfXs = intdiv($quantityAsInt, $x);
if ($offer->getOfferType()->equals(SpecialOfferType::THREE_FOR_TWO()) && $quantityAsInt > 2) {
$discountAmount = $quantity * $unitPrice - ($numberOfXs * 2 * $unitPrice + $quantityAsInt % 3 * $unitPrice);
$discount = new Discount($p, '3 for 2', -$discountAmount);
$discount = new Discount($p, self::THREE_FOR_TWO_DESCRIPTION, -$discountAmount);
}

if ($offer->getOfferType()->equals(SpecialOfferType::TEN_PERCENT_DISCOUNT())) {
$discount = new Discount(
$p,
"{$offer->getArgument()}% off",
"{$offer->getArgument()}" . self::PERCENT_OFF_SUFFIX,
-$quantity * $unitPrice * $offer->getArgument() / 100.0
);
}
Expand Down
13 changes: 9 additions & 4 deletions python/shopping_cart.py
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Expand Up @@ -3,6 +3,11 @@
from model_objects import ProductQuantity, SpecialOfferType, Discount


# Discount description constants
THREE_FOR_TWO_DESCRIPTION = "3 for 2"
PERCENT_OFF_SUFFIX = " % off"


class ShoppingCart:

def __init__(self):
Expand Down Expand Up @@ -44,7 +49,7 @@ def handle_offers(self, receipt, offers, catalog):
if quantity_as_int >= 2:
total = offer.argument * (quantity_as_int / x) + quantity_as_int % 2 * unit_price
discount_n = unit_price * quantity - total
discount = Discount(p, "2 for " + str(offer.argument), -discount_n)
discount = Discount(p, f"2 for {offer.argument}", -discount_n)

if offer.offer_type == SpecialOfferType.FIVE_FOR_AMOUNT:
x = 5
Expand All @@ -53,16 +58,16 @@ def handle_offers(self, receipt, offers, catalog):
if offer.offer_type == SpecialOfferType.THREE_FOR_TWO and quantity_as_int > 2:
discount_amount = quantity * unit_price - (
(number_of_x * 2 * unit_price) + quantity_as_int % 3 * unit_price)
discount = Discount(p, "3 for 2", -discount_amount)
discount = Discount(p, THREE_FOR_TWO_DESCRIPTION, -discount_amount)

if offer.offer_type == SpecialOfferType.TEN_PERCENT_DISCOUNT:
discount = Discount(p, str(offer.argument) + "% off",
discount = Discount(p, f"{offer.argument}{PERCENT_OFF_SUFFIX}",
-quantity * unit_price * offer.argument / 100.0)

if offer.offer_type == SpecialOfferType.FIVE_FOR_AMOUNT and quantity_as_int >= 5:
discount_total = unit_price * quantity - (
offer.argument * number_of_x + quantity_as_int % 5 * unit_price)
discount = Discount(p, str(x) + " for " + str(offer.argument), -discount_total)
discount = Discount(p, f"{x} for {offer.argument}", -discount_total)

if discount:
receipt.add_discount(discount)
13 changes: 9 additions & 4 deletions python_pytest/src/shopping_cart.py
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Expand Up @@ -3,6 +3,11 @@
from model_objects import ProductQuantity, SpecialOfferType, Discount


# Discount description constants
THREE_FOR_TWO_DESCRIPTION = "3 for 2"
PERCENT_OFF_SUFFIX = " % off"


class ShoppingCart:

def __init__(self):
Expand Down Expand Up @@ -44,7 +49,7 @@ def handle_offers(self, receipt, offers, catalog):
if quantity_as_int >= 2:
total = offer.argument * (quantity_as_int / x) + quantity_as_int % 2 * unit_price
discount_n = unit_price * quantity - total
discount = Discount(p, "2 for " + str(offer.argument), -discount_n)
discount = Discount(p, f"2 for {offer.argument}", -discount_n)

if offer.offer_type == SpecialOfferType.FIVE_FOR_AMOUNT:
x = 5
Expand All @@ -53,16 +58,16 @@ def handle_offers(self, receipt, offers, catalog):
if offer.offer_type == SpecialOfferType.THREE_FOR_TWO and quantity_as_int > 2:
discount_amount = quantity * unit_price - (
(number_of_x * 2 * unit_price) + quantity_as_int % 3 * unit_price)
discount = Discount(p, "3 for 2", -discount_amount)
discount = Discount(p, THREE_FOR_TWO_DESCRIPTION, -discount_amount)

if offer.offer_type == SpecialOfferType.TEN_PERCENT_DISCOUNT:
discount = Discount(p, str(offer.argument) + "% off",
discount = Discount(p, f"{offer.argument}{PERCENT_OFF_SUFFIX}",
-quantity * unit_price * offer.argument / 100.0)

if offer.offer_type == SpecialOfferType.FIVE_FOR_AMOUNT and quantity_as_int >= 5:
discount_total = unit_price * quantity - (
offer.argument * number_of_x + quantity_as_int % 5 * unit_price)
discount = Discount(p, str(x) + " for " + str(offer.argument), -discount_total)
discount = Discount(p, f"{x} for {offer.argument}", -discount_total)

if discount:
receipt.add_discount(discount)
8 changes: 6 additions & 2 deletions ruby/lib/models/shopping_cart.rb
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@@ -1,5 +1,9 @@
class ShoppingCart

# Discount description constants
THREE_FOR_TWO_DESCRIPTION = "3 for 2"
PERCENT_OFF_SUFFIX = " % off"

def initialize
@items = []
@product_quantities = {}
Expand Down Expand Up @@ -54,10 +58,10 @@ def handle_offers(receipt, offers, catalog)
number_of_x = quantity_as_int / x
if offer.offer_type == SpecialOfferType::THREE_FOR_TWO && quantity_as_int > 2
discount_amount = quantity * unit_price - ((number_of_x * 2 * unit_price) + quantity_as_int % 3 * unit_price)
discount = Discount.new(p, "3 for 2", discount_amount)
discount = Discount.new(p, THREE_FOR_TWO_DESCRIPTION, discount_amount)
end
if offer.offer_type == SpecialOfferType::TEN_PERCENT_DISCOUNT
discount = Discount.new(p, offer.argument.to_s + "% off", quantity * unit_price * offer.argument / 100.0)
discount = Discount.new(p, offer.argument.to_s + PERCENT_OFF_SUFFIX, quantity * unit_price * offer.argument / 100.0)
end
if offer.offer_type == SpecialOfferType::FIVE_FOR_AMOUNT && quantity_as_int >= 5
discount_total = unit_price * quantity - (offer.argument * number_of_x + quantity_as_int % 5 * unit_price)
Expand Down
8 changes: 6 additions & 2 deletions swift/SupermarketReceipt/ShoppingCart.swift
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@@ -1,5 +1,9 @@
public class ShoppingCart {

// Discount description constants
private static let threeForTwoDescription = "3 for 2"
private static let percentOffSuffix = " % off"

public var items = [ProductQuantity]()
public var productQuantities = [Product: Double]()

Expand Down Expand Up @@ -52,10 +56,10 @@ public class ShoppingCart {
var right = Double(quantityAsInt % 3) * unitPrice
var lastPart = left + right
var discountAmount = ((quantity ?? 1) * unitPrice) - lastPart
discount = Discount(description: "3 for 2", discountAmount: discountAmount, product: p)
discount = Discount(description: ShoppingCart.threeForTwoDescription, discountAmount: discountAmount, product: p)
}
if offer?.offerType == SpecialOfferType.TenPercentDiscount {
discount = Discount(description: "\(offer!.argument)% off", discountAmount: (quantity ?? 1) * unitPrice * (offer?.argument ?? 1) / 100.0, product: p)
discount = Discount(description: "\(offer!.argument)\(ShoppingCart.percentOffSuffix)", discountAmount: (quantity ?? 1) * unitPrice * (offer?.argument ?? 1) / 100.0, product: p)
}
if offer?.offerType == SpecialOfferType.FiveForAmount && quantityAsInt >= 5 {
var left = (unitPrice * (quantity ?? 1))
Expand Down
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