feat(workshop): add bonus exercises for custom providers and currencies

Introduce optional bonus tasks in part4 covering:
- CSV-based exchange rate provider
- historical exchange rate provider with date handling
- custom currency (DKP) with bidirectional conversion

Provide exercise scaffolding and tests for all scenarios.

Signed-off-by: Marcus Fihlon <marcus@fihlon.swiss>

src/main/java/swiss/fihlon/workshop/money/part1/ArithmeticExercises.java

@@ -21,7 +21,7 @@ public class ArithmeticExercises {
      * @return sum of both amounts in the same currency
      */
     public MonetaryAmount addAmounts(MonetaryAmount firstAmount, MonetaryAmount secondAmount) {
-        return firstAmount.add(secondAmount);
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -34,7 +34,7 @@ public class ArithmeticExercises {
      * @return difference after subtraction in the same currency
      */
     public MonetaryAmount subtractAmounts(MonetaryAmount minuend, MonetaryAmount subtrahend) {
-        return minuend.subtract(subtrahend);
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -47,7 +47,7 @@ public class ArithmeticExercises {
      * @return product amount in the same currency
      */
     public MonetaryAmount multiplyAmount(MonetaryAmount amount, int factor) {
-        return amount.multiply(factor);
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -60,6 +60,6 @@ public class ArithmeticExercises {
      * @return {@code true} if first amount is greater, otherwise {@code false}
      */
     public boolean compareAmounts(MonetaryAmount firstAmount, MonetaryAmount secondAmount) {
-        return firstAmount.isGreaterThan(secondAmount);
+        throw new UnsupportedOperationException("TODO");
     }
 }

src/main/java/swiss/fihlon/workshop/money/part1/FormattingExercises.java

@@ -1,9 +1,6 @@
 package swiss.fihlon.workshop.money.part1;
 
-import java.util.Locale;
 import javax.money.MonetaryAmount;
-import javax.money.format.MonetaryAmountFormat;
-import javax.money.format.MonetaryFormats;
 
 /**
  * <p>Part 1 workshop exercises for formatting monetary amounts using JSR-354.</p>
@@ -24,7 +21,7 @@ public class FormattingExercises {
      * @return formatted amount string for Swiss German locale
      */
     public String formatSwissGerman(MonetaryAmount amount) {
-        return format(amount, "de-CH");
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -36,7 +33,7 @@ public class FormattingExercises {
      * @return formatted amount string for German locale
      */
     public String formatGerman(MonetaryAmount amount) {
-        return format(amount, "de-DE");
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -48,20 +45,6 @@ public class FormattingExercises {
      * @return formatted amount string for US locale
      */
     public String formatUs(MonetaryAmount amount) {
-        return format(amount, "en-US");
-    }
-
-    /**
-     * <p>Format the given amount using the specified locale.</p>
-     *
-     * <p>Use the provided language tag to obtain a locale-specific formatter.</p>
-     *
-     * @param amount the amount to format
-     * @param languageTag IETF BCP 47 language tag (e.g. {@code de-CH})
-     * @return formatted amount string
-     */
-    private String format(MonetaryAmount amount, String languageTag) {
-        MonetaryAmountFormat format = MonetaryFormats.getAmountFormat(Locale.forLanguageTag(languageTag));
-        return format.format(amount);
+        throw new UnsupportedOperationException("TODO");
     }
 }

src/main/java/swiss/fihlon/workshop/money/part1/IntegrationExercises.java

@@ -1,13 +1,5 @@
 package swiss.fihlon.workshop.money.part1;
 
-import java.util.Locale;
-import javax.money.Monetary;
-import javax.money.MonetaryAmount;
-import javax.money.MonetaryOperator;
-import javax.money.format.MonetaryAmountFormat;
-import javax.money.format.MonetaryFormats;
-import org.javamoney.moneta.Money;
-
 /**
  * <p>Part 1 workshop exercises for combining parsing, arithmetic, rounding, and formatting with JSR-354.</p>
  *
@@ -30,24 +22,6 @@ public class IntegrationExercises {
      * @return formatted final price text
      */
     public String calculateFinalPrice(String priceText) {
-        // setup locale and formatter
-        Locale swissGerman = Locale.forLanguageTag("de-CH");
-        MonetaryAmountFormat format = MonetaryFormats.getAmountFormat(swissGerman);
-
-        // parse
-        MonetaryAmount price = format.parse(priceText);
-
-        // constants
-        MonetaryAmount shipping = Money.of(4.95, "CHF");
-        MonetaryAmount discount = Money.of(2.00, "CHF");
-
-        // calculate
-        MonetaryAmount total = price.add(shipping).subtract(discount);
-
-        // round
-        MonetaryAmount roundedTotal = total.with(Monetary.getDefaultRounding());
-
-        // format
-        return format.format(roundedTotal);
+        throw new UnsupportedOperationException("TODO");
     }
 }

src/main/java/swiss/fihlon/workshop/money/part1/MoneyExercises.java

@@ -1,9 +1,6 @@
 package swiss.fihlon.workshop.money.part1;
 
-import org.javamoney.moneta.Money;
-
 import javax.money.CurrencyUnit;
-import javax.money.Monetary;
 import javax.money.MonetaryAmount;
 
 /**
@@ -22,7 +19,7 @@ public class MoneyExercises {
      * @return Swiss franc currency unit ({@code CHF})
      */
     public CurrencyUnit createSwissFranc() {
-        return Monetary.getCurrency("CHF");
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -32,7 +29,7 @@ public class MoneyExercises {
      * @return monetary amount {@code 19.95 CHF}
      */
     public MonetaryAmount createSwissFrancAmount() {
-        return Money.of(19.95, "CHF");
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -42,7 +39,7 @@ public class MoneyExercises {
      * @return monetary amount {@code 2500 JPY}
      */
     public MonetaryAmount createJapaneseYenAmount() {
-        return Money.of(2500, "JPY");
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -52,6 +49,6 @@ public class MoneyExercises {
      * @return monetary amount {@code 12.345 TND}
      */
     public MonetaryAmount createTunisianDinarAmount() {
-        return Money.of(12.345, "TND");
+        throw new UnsupportedOperationException("TODO");
     }
 }

src/main/java/swiss/fihlon/workshop/money/part1/ParsingExercises.java

@@ -1,9 +1,6 @@
 package swiss.fihlon.workshop.money.part1;
 
 import javax.money.MonetaryAmount;
-import javax.money.format.MonetaryAmountFormat;
-import javax.money.format.MonetaryFormats;
-import javax.money.format.MonetaryParseException;
 import java.util.Locale;
 
 /**
@@ -27,7 +24,7 @@ public class ParsingExercises {
      * @return parsed monetary amount
      */
     public MonetaryAmount parseSwissGerman(String text) {
-        return parse(text, "de-CH");
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -39,7 +36,7 @@ public class ParsingExercises {
      * @return parsed monetary amount
      */
     public MonetaryAmount parseGerman(String text) {
-        return parse(text, "de-DE");
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -51,22 +48,7 @@ public class ParsingExercises {
      * @return parsed monetary amount
      */
     public MonetaryAmount parseUs(String text) {
-        return parse(text, "en-US");
-    }
-
-    /**
-     * <p>Parse the given monetary amount text using the specified locale.</p>
-     *
-     * <p>Use the provided language tag to obtain a locale-specific parser.</p>
-     *
-     * @param text the input text to parse
-     * @param languageTag IETF BCP 47 language tag (e.g. {@code de-CH})
-     * @return parsed monetary amount
-     */
-    private MonetaryAmount parse(String text, String languageTag) {
-        MonetaryAmountFormat format =
-                MonetaryFormats.getAmountFormat(Locale.forLanguageTag(languageTag));
-        return format.parse(text);
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -79,12 +61,6 @@ public class ParsingExercises {
      * @return {@code true} if parsing succeeds, otherwise {@code false}
      */
     public boolean parseInvalidInput(String text, Locale locale) {
-        MonetaryAmountFormat format = MonetaryFormats.getAmountFormat(locale);
-        try {
-            format.parse(text);
-            return true;
-        } catch (MonetaryParseException exception) {
-            return false;
-        }
+        throw new UnsupportedOperationException("TODO");
     }
 }

src/main/java/swiss/fihlon/workshop/money/part1/RoundingExercises.java

@@ -1,8 +1,6 @@
 package swiss.fihlon.workshop.money.part1;
 
-import javax.money.Monetary;
 import javax.money.MonetaryAmount;
-import javax.money.MonetaryOperator;
 
 /**
  * <p>Part 1 workshop exercises for currency-aware rounding with JSR-354.</p>
@@ -22,7 +20,7 @@ public class RoundingExercises {
      * @return rounded amount
      */
     public MonetaryAmount applyDefaultRounding(MonetaryAmount amount) {
-        return amount.with(Monetary.getDefaultRounding());
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -35,7 +33,6 @@ public class RoundingExercises {
      * @return divided and rounded amount
      */
     public MonetaryAmount divideAndRound(MonetaryAmount amount, int divisor) {
-        return amount.divide(divisor)
-                .with(Monetary.getDefaultRounding());
+        throw new UnsupportedOperationException("TODO");
     }
 }

src/main/java/swiss/fihlon/workshop/money/part2/CurrencyConversionExercises.java

@@ -2,7 +2,6 @@ package swiss.fihlon.workshop.money.part2;
 
 import javax.money.MonetaryAmount;
 import javax.money.convert.CurrencyConversion;
-import javax.money.convert.MonetaryConversions;
 
 /**
  * <p>Part 2 workshop exercises for currency conversion using JSR-354.</p>
@@ -21,7 +20,7 @@ public class CurrencyConversionExercises {
      * @return currency conversion to EUR
      */
     public CurrencyConversion getEurConversion() {
-        return MonetaryConversions.getConversion("EUR", "ECB");
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -33,7 +32,6 @@ public class CurrencyConversionExercises {
      * @return converted amount in EUR
      */
     public MonetaryAmount convertChfToEur(MonetaryAmount amount) {
-        CurrencyConversion conversion = getEurConversion();
-        return amount.with(conversion);
+        throw new UnsupportedOperationException("TODO");
     }
 }

src/main/java/swiss/fihlon/workshop/money/part2/MonetaryContextExercises.java

@@ -22,7 +22,7 @@ public class MonetaryContextExercises {
      * @return monetary context of the amount
      */
     public MonetaryContext getMonetaryContext(MonetaryAmount amount) {
-        return amount.getContext();
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -34,7 +34,7 @@ public class MonetaryContextExercises {
      * @return maximum scale from the monetary context
      */
     public int getMaxScale(MonetaryAmount amount) {
-        return amount.getContext().getMaxScale();
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -47,7 +47,7 @@ public class MonetaryContextExercises {
      * @return {@code true} if both contexts are equal, otherwise {@code false}
      */
     public boolean compareContexts(MonetaryAmount firstAmount, MonetaryAmount secondAmount) {
-        return firstAmount.getContext().equals(secondAmount.getContext());
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -59,7 +59,6 @@ public class MonetaryContextExercises {
      * @return formatted context description
      */
     public String describeContext(MonetaryAmount amount) {
-        MonetaryContext context = amount.getContext();
-        return "precision=" + context.getPrecision() + ", maxScale=" + context.getMaxScale();
+        throw new UnsupportedOperationException("TODO");
     }
 }

src/main/java/swiss/fihlon/workshop/money/part2/MonetaryOperatorExercises.java

@@ -1,13 +1,14 @@
 package swiss.fihlon.workshop.money.part2;
 
-import java.math.BigDecimal;
 import javax.money.MonetaryAmount;
 import javax.money.MonetaryOperator;
 
 /**
  * <p>Part 2 workshop exercises for encapsulating domain logic with MonetaryOperator.</p>
  *
- * <p>The examples focus on applying reusable monetary operations such as discounts and VAT.</p>
+ * <p>The exercises focus on applying reusable monetary operations such as discounts and VAT.</p>
+ *
+ * <p>The methods are intentionally incomplete and should be implemented by making tests pass.</p>
  */
 public class MonetaryOperatorExercises {
 
@@ -20,8 +21,7 @@ public class MonetaryOperatorExercises {
      * @return discounted amount
      */
     public MonetaryAmount applyDiscount(MonetaryAmount amount) {
-        MonetaryOperator discount = createDiscountOperator();
-        return amount.with(discount);
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -33,8 +33,7 @@ public class MonetaryOperatorExercises {
      * @return amount after VAT
      */
     public MonetaryAmount applyVat(MonetaryAmount amount) {
-        MonetaryOperator vat = createVatOperator();
-        return amount.with(vat);
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -46,18 +45,7 @@ public class MonetaryOperatorExercises {
      * @return amount after discount and VAT
      */
     public MonetaryAmount applyDiscountThenVat(MonetaryAmount amount) {
-        MonetaryOperator discount = createDiscountOperator();
-        MonetaryOperator vat = createVatOperator();
-        return amount.with(discount).with(vat);
-    }
-
-    /**
-     * <p>Create a reusable 7.7% VAT monetary operator.</p>
-     *
-     * @return a reusable VAT operator
-     */
-    public MonetaryOperator createVatOperator() {
-        return monetaryAmount -> monetaryAmount.multiply(new BigDecimal("1.077"));
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -68,6 +56,6 @@ public class MonetaryOperatorExercises {
      * @return reusable discount operator
      */
     public MonetaryOperator createDiscountOperator() {
-        return monetaryAmount -> monetaryAmount.multiply(new BigDecimal("0.90"));
+        throw new UnsupportedOperationException("TODO");
     }
 }

src/main/java/swiss/fihlon/workshop/money/part2/MonetaryQueryExercises.java

@@ -7,7 +7,9 @@ import javax.money.MonetaryQuery;
 /**
  * <p>Part 2 workshop exercises for extracting information from monetary amounts with MonetaryQuery.</p>
  *
- * <p>The examples focus on encapsulating reusable query logic for monetary values and currencies.</p>
+ * <p>The exercises focus on encapsulating reusable query logic for monetary values and currencies.</p>
+ *
+ * <p>The methods are intentionally incomplete and should be implemented by making tests pass.</p>
  */
 public class MonetaryQueryExercises {
 
@@ -20,7 +22,7 @@ public class MonetaryQueryExercises {
      * @return currency code
      */
     public String queryCurrencyCode(MonetaryAmount amount) {
-        return amount.query(createCurrencyCodeQuery());
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -32,9 +34,7 @@ public class MonetaryQueryExercises {
      * @return default fraction digits of the currency
      */
     public int queryDefaultFractionDigits(MonetaryAmount amount) {
-        MonetaryQuery<Integer> query =
-                monetaryAmount -> monetaryAmount.getCurrency().getDefaultFractionDigits();
-        return amount.query(query);
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -46,9 +46,7 @@ public class MonetaryQueryExercises {
      * @return numeric value as BigDecimal
      */
     public BigDecimal queryNumberAsBigDecimal(MonetaryAmount amount) {
-        MonetaryQuery<BigDecimal> query =
-                monetaryAmount -> monetaryAmount.getNumber().numberValueExact(BigDecimal.class);
-        return amount.query(query);
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -59,6 +57,6 @@ public class MonetaryQueryExercises {
      * @return reusable query returning a currency code
      */
     public MonetaryQuery<String> createCurrencyCodeQuery() {
-        return monetaryAmount -> monetaryAmount.getCurrency().getCurrencyCode();
+        throw new UnsupportedOperationException("TODO");
     }
 }

src/main/java/swiss/fihlon/workshop/money/part2/RoundingStrategyExercises.java

@@ -1,15 +1,14 @@
 package swiss.fihlon.workshop.money.part2;
 
-import java.math.BigDecimal;
-import java.math.RoundingMode;
-import javax.money.Monetary;
 import javax.money.MonetaryAmount;
 import javax.money.MonetaryOperator;
 
 /**
- * <p>Part 2 workshop examples for applying different rounding strategies with JSR-354.</p>
+ * <p>Part 2 workshop exercises for applying different rounding strategies with JSR-354.</p>
  *
- * <p>The examples focus on treating rounding as an explicit domain decision that depends on the use case.</p>
+ * <p>The exercises focus on treating rounding as an explicit domain decision that depends on the use case.</p>
+ *
+ * <p>The methods are intentionally incomplete and should be implemented by making tests pass.</p>
  */
 public class RoundingStrategyExercises {
 
@@ -22,8 +21,7 @@ public class RoundingStrategyExercises {
      * @return amount rounded with default currency rounding
      */
     public MonetaryAmount applyDefaultRounding(MonetaryAmount amount) {
-        MonetaryOperator rounding = Monetary.getDefaultRounding();
-        return amount.with(rounding);
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -35,8 +33,7 @@ public class RoundingStrategyExercises {
      * @return CHF amount rounded to the nearest 0.05
      */
     public MonetaryAmount applySwissCashRounding(MonetaryAmount amount) {
-        MonetaryOperator swissCashRounding = createSwissCashRounding();
-        return amount.with(swissCashRounding);
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -47,19 +44,6 @@ public class RoundingStrategyExercises {
      * @return reusable Swiss cash rounding operator
      */
     public MonetaryOperator createSwissCashRounding() {
-        return monetaryAmount -> {
-            if (!"CHF".equals(monetaryAmount.getCurrency().getCurrencyCode())) {
-                throw new IllegalArgumentException("Swiss cash rounding only supports CHF.");
-            }
-
-            BigDecimal increment = new BigDecimal("0.05");
-            BigDecimal value = monetaryAmount.getNumber().numberValueExact(BigDecimal.class);
-            BigDecimal rounded = value.divide(increment, 0, RoundingMode.HALF_UP).multiply(increment);
-
-            return monetaryAmount.getFactory()
-                    .setCurrency(monetaryAmount.getCurrency())
-                    .setNumber(rounded)
-                    .create();
-        };
+        throw new UnsupportedOperationException("TODO");
     }
 }

src/main/java/swiss/fihlon/workshop/money/part3/OrderExercises.java

@@ -1,19 +1,14 @@
 package swiss.fihlon.workshop.money.part3;
 
-import java.math.BigDecimal;
-import java.util.Locale;
 import javax.money.CurrencyUnit;
-import javax.money.Monetary;
 import javax.money.MonetaryAmount;
-import javax.money.MonetaryOperator;
-import javax.money.convert.MonetaryConversions;
-import javax.money.format.MonetaryAmountFormat;
-import javax.money.format.MonetaryFormats;
 
 /**
- * <p>Part 3 workshop examples for integrating monetary calculations into a small order workflow.</p>
+ * <p>Part 3 workshop exercises for integrating monetary calculations into a small order workflow.</p>
  *
- * <p>The examples focus on combining subtotal calculation, discount, VAT, rounding, and formatting.</p>
+ * <p>The exercises focus on combining subtotal calculation, discount, VAT, rounding, and formatting.</p>
+ *
+ * <p>The methods are intentionally incomplete and should be implemented by making tests pass.</p>
  */
 public class OrderExercises {
 
@@ -27,7 +22,7 @@ public class OrderExercises {
      * @return subtotal amount
      */
     public MonetaryAmount calculateSubtotal(MonetaryAmount unitPrice, int quantity) {
-        return unitPrice.multiply(quantity);
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -39,8 +34,7 @@ public class OrderExercises {
      * @return discounted amount
      */
     public MonetaryAmount applyDiscount(MonetaryAmount subtotal) {
-        MonetaryOperator discount = amount -> amount.multiply(new BigDecimal("0.90"));
-        return subtotal.with(discount);
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -52,9 +46,7 @@ public class OrderExercises {
      * @return VAT-inclusive amount
      */
     public MonetaryAmount applyVat(MonetaryAmount discountedAmount) {
-        MonetaryAmount vatInclusiveAmount = discountedAmount.multiply(new BigDecimal("1.077"));
-        MonetaryOperator rounding = Monetary.getDefaultRounding();
-        return vatInclusiveAmount.with(rounding);
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -67,9 +59,7 @@ public class OrderExercises {
      * @return final total amount
      */
     public MonetaryAmount calculateTotal(MonetaryAmount unitPrice, int quantity) {
-        MonetaryAmount subtotal = calculateSubtotal(unitPrice, quantity);
-        MonetaryAmount discountedAmount = applyDiscount(subtotal);
-        return applyVat(discountedAmount);
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -81,8 +71,7 @@ public class OrderExercises {
      * @return formatted total string
      */
     public String formatTotal(MonetaryAmount total) {
-        MonetaryAmountFormat format = MonetaryFormats.getAmountFormat(Locale.forLanguageTag("de-CH"));
-        return format.format(total);
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -95,6 +84,6 @@ public class OrderExercises {
      * @return amount converted to the target currency
      */
     public MonetaryAmount convertToCurrency(MonetaryAmount amount, CurrencyUnit targetCurrency) {
-        return amount.with(MonetaryConversions.getConversion(targetCurrency, "ECB"));
+        throw new UnsupportedOperationException("TODO");
     }
 }

src/main/java/swiss/fihlon/workshop/money/part4/CsvExchangeRateProvider.java

@@ -1,30 +1,18 @@
 package swiss.fihlon.workshop.money.part4;
 
-import java.io.BufferedReader;
-import java.io.InputStream;
-import java.io.InputStreamReader;
-import java.math.BigDecimal;
-import java.nio.charset.StandardCharsets;
-import java.util.HashMap;
-import java.util.Map;
 import javax.money.convert.ConversionQuery;
-import javax.money.convert.ConversionContext;
-import javax.money.convert.ConversionContextBuilder;
 import javax.money.convert.CurrencyConversion;
 import javax.money.convert.ExchangeRate;
 import javax.money.convert.ExchangeRateProvider;
 import javax.money.convert.ProviderContext;
-import javax.money.convert.ProviderContextBuilder;
-import javax.money.convert.RateType;
-import org.javamoney.moneta.convert.ExchangeRateBuilder;
-import org.javamoney.moneta.spi.DefaultNumberValue;
-import org.javamoney.moneta.spi.LazyBoundCurrencyConversion;
 
 /**
  * <p>Bonus exercise 1 for implementing a local CSV-based exchange rate provider with JSR-354.</p>
  *
  * <p>The provider is intended for workshop usage and should read rates from the classpath resource
  * {@code exchange-rates.csv}.</p>
+ *
+ * <p>The implementation is intentionally incomplete and should be finished by making tests pass.</p>
  */
 public class CsvExchangeRateProvider implements ExchangeRateProvider {
 
@@ -32,10 +20,6 @@ public class CsvExchangeRateProvider implements ExchangeRateProvider {
      * <p>Name of the classpath CSV resource containing exchange rates.</p>
      */
     public static final String RESOURCE_NAME = "exchange-rates.csv";
-    private static final ProviderContext CONTEXT =
-            ProviderContextBuilder.of("csv-exchange-rate-provider", RateType.HISTORIC).build();
-
-    private final Map<CurrencyPair, BigDecimal> ratesByPair;
 
     /**
      * <p>Create a new provider instance.</p>
@@ -43,7 +27,6 @@ public class CsvExchangeRateProvider implements ExchangeRateProvider {
      * <p>The provider should load exchange rates from {@link #RESOURCE_NAME}.</p>
      */
     public CsvExchangeRateProvider() {
-        this.ratesByPair = loadRates();
     }
 
     /**
@@ -53,7 +36,7 @@ public class CsvExchangeRateProvider implements ExchangeRateProvider {
      */
     @Override
     public ProviderContext getContext() {
-        return CONTEXT;
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -64,16 +47,7 @@ public class CsvExchangeRateProvider implements ExchangeRateProvider {
      */
     @Override
     public ExchangeRate getExchangeRate(ConversionQuery conversionQuery) {
-        CurrencyPair currencyPair = CurrencyPair.from(conversionQuery);
-        BigDecimal factor = ratesByPair.get(currencyPair);
-        if (factor == null) {
-            return null;
-        }
-        return new ExchangeRateBuilder(getContext().getProviderName(), RateType.DEFERRED)
-                .setBase(conversionQuery.getBaseCurrency())
-                .setTerm(conversionQuery.getCurrency())
-                .setFactor(DefaultNumberValue.of(factor))
-                .build();
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -86,60 +60,6 @@ public class CsvExchangeRateProvider implements ExchangeRateProvider {
      */
     @Override
     public CurrencyConversion getCurrencyConversion(ConversionQuery conversionQuery) {
-        if (getExchangeRate(conversionQuery) == null) {
-            return null;
-        }
-        ConversionContext conversionContext = ConversionContextBuilder.create(getContext(), RateType.DEFERRED).build();
-        return new LazyBoundCurrencyConversion(conversionQuery, this, conversionContext);
-    }
-
-    /**
-     * <p>Load exchange rates from the classpath CSV resource into a lookup map.</p>
-     *
-     * <p>The CSV is expected to contain a header and records in the format
-     * {@code base,term,rate}.</p>
-     *
-     * @return map keyed by currency pair containing the configured exchange factor
-     */
-    private static Map<CurrencyPair, BigDecimal> loadRates() {
-        InputStream inputStream = CsvExchangeRateProvider.class.getClassLoader().getResourceAsStream(RESOURCE_NAME);
-        if (inputStream == null) {
-            throw new IllegalStateException("Could not load classpath resource: " + RESOURCE_NAME);
-        }
-
-        try (BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8))) {
-            Map<CurrencyPair, BigDecimal> rates = new HashMap<>();
-            reader.readLine();
-            String line;
-            while ((line = reader.readLine()) != null) {
-                String[] values = line.split(",");
-                CurrencyPair currencyPair = new CurrencyPair(values[0], values[1]);
-                BigDecimal factor = new BigDecimal(values[2]);
-                rates.put(currencyPair, factor);
-            }
-            return rates;
-        } catch (Exception exception) {
-            throw new IllegalStateException("Failed to parse exchange rates from: " + RESOURCE_NAME, exception);
-        }
-    }
-
-    /**
-     * <p>Simple key for identifying an exchange rate by base and term currency code.</p>
-     *
-     * @param baseCurrencyCode ISO currency code of the base currency
-     * @param termCurrencyCode ISO currency code of the term currency
-     */
-    private record CurrencyPair(String baseCurrencyCode, String termCurrencyCode) {
-        /**
-         * <p>Create a currency-pair key from a conversion query.</p>
-         *
-         * @param conversionQuery query containing base and term currency
-         * @return key for map-based rate lookup
-         */
-        private static CurrencyPair from(ConversionQuery conversionQuery) {
-            return new CurrencyPair(
-                    conversionQuery.getBaseCurrency().getCurrencyCode(),
-                    conversionQuery.getCurrency().getCurrencyCode());
-        }
+        throw new UnsupportedOperationException("TODO");
     }
 }

src/main/java/swiss/fihlon/workshop/money/part4/CsvHistoricalExchangeRateProvider.java

@@ -1,27 +1,11 @@
 package swiss.fihlon.workshop.money.part4;
 
-import java.io.BufferedReader;
-import java.io.InputStream;
-import java.io.InputStreamReader;
-import java.math.BigDecimal;
 import java.time.LocalDate;
-import java.nio.charset.StandardCharsets;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.NavigableMap;
-import java.util.TreeMap;
 import javax.money.convert.ConversionQuery;
-import javax.money.convert.ConversionContext;
-import javax.money.convert.ConversionContextBuilder;
 import javax.money.convert.CurrencyConversion;
 import javax.money.convert.ExchangeRate;
 import javax.money.convert.ExchangeRateProvider;
 import javax.money.convert.ProviderContext;
-import javax.money.convert.ProviderContextBuilder;
-import javax.money.convert.RateType;
-import org.javamoney.moneta.convert.ExchangeRateBuilder;
-import org.javamoney.moneta.spi.DefaultNumberValue;
-import org.javamoney.moneta.spi.LazyBoundCurrencyConversion;
 
 /**
  * <p>Bonus exercise 2 for implementing a local CSV-based historical exchange rate provider with JSR-354.</p>
@@ -30,6 +14,8 @@ import org.javamoney.moneta.spi.LazyBoundCurrencyConversion;
  * {@code exchange-rates-hist.csv}.</p>
  *
  * <p>The lookup should use base currency, term currency, and a date passed in the query context.</p>
+ *
+ * <p>The implementation is intentionally incomplete and should be finished by making tests pass.</p>
  */
 public class CsvHistoricalExchangeRateProvider implements ExchangeRateProvider {
 
@@ -42,10 +28,6 @@ public class CsvHistoricalExchangeRateProvider implements ExchangeRateProvider {
      * <p>Query key type for historical lookups.</p>
      */
     public static final Class<LocalDate> DATE_QUERY_KEY = LocalDate.class;
-    private static final ProviderContext CONTEXT =
-            ProviderContextBuilder.of("csv-historical-exchange-rate-provider", RateType.HISTORIC).build();
-
-    private final Map<CurrencyPair, NavigableMap<LocalDate, BigDecimal>> ratesByPairAndDate;
 
     /**
      * <p>Create a new provider instance.</p>
@@ -53,7 +35,6 @@ public class CsvHistoricalExchangeRateProvider implements ExchangeRateProvider {
      * <p>The provider should load exchange rates from {@link #RESOURCE_NAME}.</p>
      */
     public CsvHistoricalExchangeRateProvider() {
-        this.ratesByPairAndDate = loadRates();
     }
 
     /**
@@ -63,7 +44,7 @@ public class CsvHistoricalExchangeRateProvider implements ExchangeRateProvider {
      */
     @Override
     public ProviderContext getContext() {
-        return CONTEXT;
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -81,27 +62,7 @@ public class CsvHistoricalExchangeRateProvider implements ExchangeRateProvider {
      */
     @Override
     public ExchangeRate getExchangeRate(ConversionQuery conversionQuery) {
-        LocalDate requestedDate = conversionQuery.get(DATE_QUERY_KEY);
-        if (requestedDate == null) {
-            return null;
-        }
-
-        CurrencyPair currencyPair = CurrencyPair.from(conversionQuery);
-        NavigableMap<LocalDate, BigDecimal> ratesByDate = ratesByPairAndDate.get(currencyPair);
-        if (ratesByDate == null) {
-            return null;
-        }
-
-        Map.Entry<LocalDate, BigDecimal> bestMatch = ratesByDate.floorEntry(requestedDate);
-        if (bestMatch == null) {
-            return null;
-        }
-
-        return new ExchangeRateBuilder(getContext().getProviderName(), RateType.HISTORIC)
-                .setBase(conversionQuery.getBaseCurrency())
-                .setTerm(conversionQuery.getCurrency())
-                .setFactor(DefaultNumberValue.of(bestMatch.getValue()))
-                .build();
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -117,61 +78,6 @@ public class CsvHistoricalExchangeRateProvider implements ExchangeRateProvider {
      */
     @Override
     public CurrencyConversion getCurrencyConversion(ConversionQuery conversionQuery) {
-        if (getExchangeRate(conversionQuery) == null) {
-            return null;
-        }
-        ConversionContext conversionContext = ConversionContextBuilder.create(getContext(), RateType.HISTORIC).build();
-        return new LazyBoundCurrencyConversion(conversionQuery, this, conversionContext);
-    }
-
-    /**
-     * <p>Load historical exchange rates from the classpath CSV resource into a date-indexed lookup map.</p>
-     *
-     * <p>The CSV is expected to contain a header and records in the format
-     * {@code date,base,term,rate}.</p>
-     *
-     * @return map keyed by currency pair with a navigable date-to-rate mapping
-     */
-    private static Map<CurrencyPair, NavigableMap<LocalDate, BigDecimal>> loadRates() {
-        InputStream inputStream = CsvHistoricalExchangeRateProvider.class.getClassLoader().getResourceAsStream(RESOURCE_NAME);
-        if (inputStream == null) {
-            throw new IllegalStateException("Could not load classpath resource: " + RESOURCE_NAME);
-        }
-
-        try (BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8))) {
-            Map<CurrencyPair, NavigableMap<LocalDate, BigDecimal>> rates = new HashMap<>();
-            reader.readLine();
-            String line;
-            while ((line = reader.readLine()) != null) {
-                String[] values = line.split(",");
-                LocalDate date = LocalDate.parse(values[0]);
-                CurrencyPair currencyPair = new CurrencyPair(values[1], values[2]);
-                BigDecimal factor = new BigDecimal(values[3]);
-                rates.computeIfAbsent(currencyPair, key -> new TreeMap<>()).put(date, factor);
-            }
-            return rates;
-        } catch (Exception exception) {
-            throw new IllegalStateException("Failed to parse historical exchange rates from: " + RESOURCE_NAME, exception);
-        }
-    }
-
-    /**
-     * <p>Simple key for identifying a historical exchange-rate series by base and term currency code.</p>
-     *
-     * @param baseCurrencyCode ISO currency code of the base currency
-     * @param termCurrencyCode ISO currency code of the term currency
-     */
-    private record CurrencyPair(String baseCurrencyCode, String termCurrencyCode) {
-        /**
-         * <p>Create a currency-pair key from a conversion query.</p>
-         *
-         * @param conversionQuery query containing base and term currency
-         * @return key for map-based historical rate lookup
-         */
-        private static CurrencyPair from(ConversionQuery conversionQuery) {
-            return new CurrencyPair(
-                    conversionQuery.getBaseCurrency().getCurrencyCode(),
-                    conversionQuery.getCurrency().getCurrencyCode());
-        }
+        throw new UnsupportedOperationException("TODO");
     }
 }

src/main/java/swiss/fihlon/workshop/money/part4/DukePointsExchangeRateProvider.java

@@ -1,32 +1,20 @@
 package swiss.fihlon.workshop.money.part4;
 
-import java.math.BigDecimal;
 import javax.money.convert.ConversionQuery;
-import javax.money.convert.ConversionContext;
-import javax.money.convert.ConversionContextBuilder;
 import javax.money.convert.CurrencyConversion;
 import javax.money.convert.ExchangeRate;
 import javax.money.convert.ExchangeRateProvider;
 import javax.money.convert.ProviderContext;
-import javax.money.convert.ProviderContextBuilder;
-import javax.money.convert.RateType;
-import org.javamoney.moneta.convert.ExchangeRateBuilder;
-import org.javamoney.moneta.spi.DefaultNumberValue;
-import org.javamoney.moneta.spi.LazyBoundCurrencyConversion;
 
 /**
  * <p>Bonus exercise 3 for implementing local exchange rates between CHF and DukePoints.</p>
  *
  * <p>The provider should support deterministic conversion for {@code CHF -> DKP} and {@code DKP -> CHF}.</p>
+ *
+ * <p>The implementation is intentionally incomplete and should be finished by making tests pass.</p>
  */
 public class DukePointsExchangeRateProvider implements ExchangeRateProvider {
 
-    private static final BigDecimal CHF_TO_DKP_FACTOR = new BigDecimal("0.1");
-    private static final BigDecimal DKP_TO_CHF_FACTOR = new BigDecimal("10");
-    private static final ProviderContext CONTEXT =
-            ProviderContextBuilder.of("dkp-exchange-rate-provider", RateType.HISTORIC).build();
-    private static final String CHF = "CHF";
-
     /**
      * <p>Create a new exchange rate provider for DukePoints.</p>
      */
@@ -40,7 +28,7 @@ public class DukePointsExchangeRateProvider implements ExchangeRateProvider {
      */
     @Override
     public ProviderContext getContext() {
-        return CONTEXT;
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -53,19 +41,7 @@ public class DukePointsExchangeRateProvider implements ExchangeRateProvider {
      */
     @Override
     public ExchangeRate getExchangeRate(ConversionQuery conversionQuery) {
-        String baseCurrencyCode = conversionQuery.getBaseCurrency().getCurrencyCode();
-        String termCurrencyCode = conversionQuery.getCurrency().getCurrencyCode();
-
-        BigDecimal factor = resolveFactor(baseCurrencyCode, termCurrencyCode);
-        if (factor == null) {
-            return null;
-        }
-
-        return new ExchangeRateBuilder(getContext().getProviderName(), RateType.HISTORIC)
-                .setBase(conversionQuery.getBaseCurrency())
-                .setTerm(conversionQuery.getCurrency())
-                .setFactor(DefaultNumberValue.of(factor))
-                .build();
+        throw new UnsupportedOperationException("TODO");
     }
 
     /**
@@ -78,27 +54,6 @@ public class DukePointsExchangeRateProvider implements ExchangeRateProvider {
      */
     @Override
     public CurrencyConversion getCurrencyConversion(ConversionQuery conversionQuery) {
-        if (getExchangeRate(conversionQuery) == null) {
-            return null;
-        }
-        ConversionContext conversionContext = ConversionContextBuilder.create(getContext(), RateType.HISTORIC).build();
-        return new LazyBoundCurrencyConversion(conversionQuery, this, conversionContext);
-    }
-
-    /**
-     * <p>Resolve the conversion factor for a supported DukePoints currency pair.</p>
-     *
-     * @param baseCurrencyCode currency code of the base currency
-     * @param termCurrencyCode currency code of the target currency
-     * @return conversion factor for supported pairs, otherwise {@code null}
-     */
-    private BigDecimal resolveFactor(String baseCurrencyCode, String termCurrencyCode) {
-        if (CHF.equals(baseCurrencyCode) && DukePointsCurrencyFactory.DKP.equals(termCurrencyCode)) {
-            return CHF_TO_DKP_FACTOR;
-        }
-        if (DukePointsCurrencyFactory.DKP.equals(baseCurrencyCode) && CHF.equals(termCurrencyCode)) {
-            return DKP_TO_CHF_FACTOR;
-        }
-        return null;
+        throw new UnsupportedOperationException("TODO");
     }
 }

src/test/java/swiss/fihlon/workshop/money/part2/CurrencyConversionExercisesTest.java

@@ -1,13 +1,13 @@
 package swiss.fihlon.workshop.money.part2;
 
-import static org.assertj.core.api.Assertions.assertThat;
-
-import java.time.LocalDateTime;
-import javax.money.MonetaryAmount;
-import javax.money.convert.CurrencyConversion;
 import org.javamoney.moneta.Money;
 import org.junit.jupiter.api.Test;
 
+import javax.money.MonetaryAmount;
+import javax.money.convert.CurrencyConversion;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
 class CurrencyConversionExercisesTest {
 
     private final CurrencyConversionExercises exercises = new CurrencyConversionExercises();
@@ -29,25 +29,4 @@ class CurrencyConversionExercisesTest {
         assertThat(result).isNotNull();
         assertThat(result.getCurrency().getCurrencyCode()).isEqualTo("EUR");
     }
-
-    @Test
-    void shouldCreateEurConversionForTimestamp() {
-        LocalDateTime timestamp = LocalDateTime.of(2024, 1, 15, 10, 30);
-
-        CurrencyConversion conversion = exercises.getEurConversionForTimestamp(timestamp);
-
-        assertThat(conversion).isNotNull();
-        assertThat(conversion.getCurrency().getCurrencyCode()).isEqualTo("EUR");
-    }
-
-    @Test
-    void shouldConvertChfToEurAtTimestamp() {
-        MonetaryAmount chfAmount = Money.of(10, "CHF");
-        LocalDateTime timestamp = LocalDateTime.of(2024, 1, 15, 10, 30);
-
-        MonetaryAmount result = exercises.convertChfToEurAt(chfAmount, timestamp);
-
-        assertThat(result).isNotNull();
-        assertThat(result.getCurrency().getCurrencyCode()).isEqualTo("EUR");
-    }
 }

src/test/java/swiss/fihlon/workshop/money/part2/RoundingStrategyExercisesTest.java

@@ -1,11 +1,12 @@
 package swiss.fihlon.workshop.money.part2;
 
-import java.math.BigDecimal;
-import javax.money.MonetaryAmount;
-import javax.money.MonetaryOperator;
 import org.javamoney.moneta.Money;
 import org.junit.jupiter.api.Test;
 
+import javax.money.MonetaryAmount;
+import javax.money.MonetaryOperator;
+import java.math.BigDecimal;
+
 import static org.assertj.core.api.Assertions.assertThat;
 
 class RoundingStrategyExercisesTest {
@@ -23,17 +24,6 @@ class RoundingStrategyExercisesTest {
         assertThat(result.getNumber().numberValueExact(BigDecimal.class)).isEqualByComparingTo("10.02");
     }
 
-    @Test
-    void shouldRoundVatAmount() {
-        MonetaryAmount taxAmount = Money.of(1.537, "CHF");
-
-        MonetaryAmount result = exercises.roundVatAmount(taxAmount);
-
-        assertThat(result).isNotNull();
-        assertThat(result.getCurrency().getCurrencyCode()).isEqualTo("CHF");
-        assertThat(result.getNumber().numberValueExact(BigDecimal.class)).isEqualByComparingTo("1.54");
-    }
-
     @Test
     void shouldApplySwissCashRounding() {
         MonetaryAmount firstAmount = Money.of(10.02, "CHF");