Merge pull request 'NBP service works done' from currency-service into master

.editorconfig

@@ -6,5 +6,5 @@ indent_size = 4
 insert_final_newline = true
 trim_trailing_whitespace = true
 
-[*.yaml]
+[{*.yaml,*.json}]
 indent_size = 2

pom.xml

@@ -27,8 +27,10 @@
         <maven.compiler.target>${java.version}</maven.compiler.target>
 
         <!-- dependencies -->
+        <wiremock.version>3.5.4</wiremock.version>
 
         <!-- plugins -->
+        <jsonschema2pojo.version>1.2.1</jsonschema2pojo.version>
     </properties>
 
     <dependencies>
@@ -77,6 +79,12 @@
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.wiremock</groupId>
+            <artifactId>wiremock-standalone</artifactId>
+            <version>${wiremock.version}</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>
@@ -85,6 +93,22 @@
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-maven-plugin</artifactId>
             </plugin>
+            <plugin>
+                <groupId>org.jsonschema2pojo</groupId>
+                <artifactId>jsonschema2pojo-maven-plugin</artifactId>
+                <version>${jsonschema2pojo.version}</version>
+                <configuration>
+                    <sourceDirectory>${basedir}/src/main/resources/schema</sourceDirectory>
+                    <targetPackage>eu.ztsh.wymiana.model</targetPackage>
+                </configuration>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>generate</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
         </plugins>
     </build>
 

src/main/java/eu/ztsh/wymiana/config/ClockConfiguration.java

@@ -0,0 +1,16 @@
+package eu.ztsh.wymiana.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import java.time.Clock;
+
+@Configuration
+public class ClockConfiguration {
+
+    @Bean
+    public Clock clock() {
+        return Clock.systemDefaultZone();
+    }
+
+}

src/main/java/eu/ztsh/wymiana/config/RestClientConfiguration.java

@@ -0,0 +1,18 @@
+package eu.ztsh.wymiana.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.client.RestClient;
+
+@Configuration
+public class RestClientConfiguration {
+
+    @Bean
+    public RestClient restClient() {
+        return RestClient.builder()
+            .baseUrl("http://api.nbp.pl")
+            .defaultHeader("Accept", "application/json")
+            .build();
+    }
+
+}

src/main/java/eu/ztsh/wymiana/exception/NoDataException.java

@@ -0,0 +1,9 @@
+package eu.ztsh.wymiana.exception;
+
+public class NoDataException extends RuntimeException {
+
+    public NoDataException(String code, String date) {
+        super("No data for code %s and date %s".formatted(code, date));
+    }
+
+}

src/main/java/eu/ztsh/wymiana/service/NbpService.java

@@ -0,0 +1,89 @@
+package eu.ztsh.wymiana.service;
+
+import eu.ztsh.wymiana.exception.NoDataException;
+import eu.ztsh.wymiana.model.Rates;
+import lombok.RequiredArgsConstructor;
+import org.assertj.core.util.VisibleForTesting;
+import org.springframework.http.HttpStatusCode;
+import org.springframework.stereotype.Service;
+import org.springframework.web.client.RestClient;
+
+import java.time.Clock;
+import java.time.DayOfWeek;
+import java.time.LocalDate;
+import java.time.format.DateTimeFormatter;
+import java.time.temporal.TemporalAdjusters;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+
+/**
+ * NBP exchange rates service
+ */
+@Service
+@RequiredArgsConstructor
+public class NbpService {
+
+    private final Clock clock;
+    private final RestClient restClient;
+    private static final String URI_PATTERN = "/api/exchangerates/rates/c/{code}/{date}/";
+    private final DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd");
+
+    private final ConcurrentMap<String, RatesCache> cache = new ConcurrentHashMap<>(1);
+
+    public double getSellRate(String currency) {
+        return getCurrency(currency).sell();
+    }
+
+    public double getBuyRate(String currency) {
+        return getCurrency(currency).buy();
+    }
+
+    private synchronized RatesCache getCurrency(String currency) {
+        var today = getFetchDate();
+        var cacheObject = cache.get(currency);
+        if (cacheObject == null || cacheObject.date().isBefore(today)) {
+            var fresh = fetchData(currency, dtf.format(today));
+            var rate = fresh.getRates().get(0);
+            cacheObject = new RatesCache(
+                LocalDate.parse(rate.getEffectiveDate(), dtf),
+                rate.getBid(),
+                rate.getAsk()
+            );
+            cache.put(fresh.getCode(), cacheObject);
+        }
+        return cacheObject;
+    }
+
+    /**
+     * Calculates date for data fetch.
+     * <p>
+     * Usually this would be today, but as rates are set only Mon-Fri, during weekends it is needed to fetch last friday rates.
+     *
+     * @return date for data fetch
+     */
+    @VisibleForTesting
+    LocalDate getFetchDate() {
+        var today = LocalDate.now(clock);
+        return isWeekend(today) ? today.with(TemporalAdjusters.previous(DayOfWeek.FRIDAY)) : today;
+    }
+
+    @VisibleForTesting
+    Rates fetchData(String code, String date) {
+        return restClient.get().uri(URI_PATTERN, code.toLowerCase(), date)
+            .retrieve()
+            .onStatus(HttpStatusCode::is4xxClientError, ((request, response) -> {
+                throw new NoDataException(code, date);
+            }))
+            .body(Rates.class);
+    }
+
+    private static boolean isWeekend(LocalDate today) {
+        return today.getDayOfWeek() == DayOfWeek.SATURDAY
+            || today.getDayOfWeek() == DayOfWeek.SUNDAY;
+    }
+
+    private record RatesCache(LocalDate date, double buy, double sell) {
+
+    }
+
+}

src/main/java/eu/ztsh/wymiana/validation/ValidExchangeRequest.java

@@ -0,0 +1,24 @@
+package eu.ztsh.wymiana.validation;
+
+import jakarta.validation.Constraint;
+import jakarta.validation.Payload;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import static java.lang.annotation.ElementType.TYPE_USE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+
+@Retention(RUNTIME)
+@Target({ TYPE_USE })
+@Documented
+@Constraint(validatedBy = {ValidExchangeRequestValidator.class })
+public @interface ValidExchangeRequest {
+
+    String message() default "Exchange request is not valid";
+    Class<?>[] groups() default { };
+    Class<? extends Payload>[] payload() default { };
+
+}

src/main/java/eu/ztsh/wymiana/validation/ValidExchangeRequestValidator.java

@@ -0,0 +1,24 @@
+package eu.ztsh.wymiana.validation;
+
+import eu.ztsh.wymiana.web.model.CurrencyExchangeRequest;
+import jakarta.validation.ConstraintValidator;
+import jakarta.validation.ConstraintValidatorContext;
+
+public class ValidExchangeRequestValidator implements
+    ConstraintValidator<ValidExchangeRequest, CurrencyExchangeRequest> {
+
+    @Override
+    public boolean isValid(CurrencyExchangeRequest request,
+                           ConstraintValidatorContext constraintValidatorContext) {
+        if (request == null) {
+            return false;
+        }
+
+        return !request.from().equals(request.to())
+            && !((request.toBuy() == null && request.toSell() == null)
+                || (request.toBuy() != null && request.toSell() != null))
+            && ((request.toBuy() != null && request.toBuy() >= 0)
+                || (request.toSell() != null && request.toSell() >= 0));
+    }
+
+}

src/main/java/eu/ztsh/wymiana/web/model/CurrencyExchangeRequest.java

@@ -0,0 +1,18 @@
+package eu.ztsh.wymiana.web.model;
+
+import eu.ztsh.wymiana.validation.ValidExchangeRequest;
+import jakarta.validation.constraints.NotNull;
+import lombok.Builder;
+import org.hibernate.validator.constraints.pl.PESEL;
+
+@Builder
+@ValidExchangeRequest
+public record CurrencyExchangeRequest(
+    @PESEL String pesel,
+    @NotNull String from,
+    @NotNull String to,
+    Double toBuy,
+    Double toSell
+) {
+
+}

src/main/resources/schema/rates.json

@@ -0,0 +1,53 @@
+{
+  "$id": "https://api.nbp.pl/c/rates.json",
+  "$schema": "http://json-schema.org/draft/2020-12/schema",
+  "type": "object",
+  "def": {
+    "rate": {
+      "type": "object",
+      "properties": {
+        "no": {
+          "type": "string"
+        },
+        "effectiveDate": {
+          "type": "string"
+        },
+        "bid": {
+          "type": "number"
+        },
+        "ask": {
+          "type": "number"
+        }
+      },
+      "required": [
+        "no",
+        "effectiveDate",
+        "bid",
+        "ask"
+      ]
+    }
+  },
+  "properties": {
+    "table": {
+      "type": "string"
+    },
+    "currency": {
+      "type": "string"
+    },
+    "code": {
+      "type": "string"
+    },
+    "rates": {
+      "type": "array",
+      "items": {
+        "$ref": "#/def/rate"
+      }
+    }
+  },
+  "required": [
+    "table",
+    "currency",
+    "code",
+    "rates"
+  ]
+}

src/test/java/eu/ztsh/wymiana/EntityCreator.java

@@ -2,6 +2,9 @@ package eu.ztsh.wymiana;
 
 import eu.ztsh.wymiana.data.entity.CurrencyEntity;
 import eu.ztsh.wymiana.data.entity.UserEntity;
+import eu.ztsh.wymiana.model.Rate;
+import eu.ztsh.wymiana.model.Rates;
+import eu.ztsh.wymiana.web.model.CurrencyExchangeRequest;
 import eu.ztsh.wymiana.web.model.UserCreateRequest;
 
 import java.util.ArrayList;
@@ -16,6 +19,12 @@ public class EntityCreator {
         public static String NAME = "Janina";
         public static String SURNAME = "Kowalska";
         public static double PLN = 20.10;
+        public static double USD_SELL = 5.18;
+        public static double USD_BUY = 5.08;
+        public static String PLN_SYMBOL = "PLN";
+        public static String USD_SYMBOL = "USD";
+        public static double BUY_RATE = 3.8804;
+        public static double SELL_RATE = 3.9572;
 
     }
 
@@ -30,6 +39,24 @@ public class EntityCreator {
             .pln(Constants.PLN);
     }
 
+    public static CurrencyExchangeRequest.CurrencyExchangeRequestBuilder exchangeRequest() {
+        return CurrencyExchangeRequest.builder().pesel(Constants.PESEL);
+    }
+
+    public static Rates rates(String date) {
+        var rates = new Rates();
+        rates.setTable("C");
+        rates.setCurrency("dolar amerykański");
+        rates.setCode("USD");
+        var rate = new Rate();
+        rate.setNo("096/C/NBP/2024");
+        rate.setEffectiveDate(date);
+        rate.setBid(Constants.BUY_RATE);
+        rate.setAsk(Constants.SELL_RATE);
+        rates.setRates(List.of(rate));
+        return rates;
+    }
+
     public static class UserEntityBuilder {
 
         String name;

src/test/java/eu/ztsh/wymiana/WireMockExtension.java

@@ -0,0 +1,50 @@
+package eu.ztsh.wymiana;
+
+import com.github.tomakehurst.wiremock.WireMockServer;
+import com.github.tomakehurst.wiremock.client.WireMock;
+import org.junit.jupiter.api.extension.AfterEachCallback;
+import org.junit.jupiter.api.extension.BeforeAllCallback;
+import org.junit.jupiter.api.extension.ExtensionContext;
+
+import static com.github.tomakehurst.wiremock.client.WireMock.*;
+
+public class WireMockExtension implements BeforeAllCallback, AfterEachCallback, ExtensionContext.Store.CloseableResource {
+
+    public static final String baseUrl = "http://localhost:38080";
+
+    public static void response(String endpoint, int status, String body) {
+        configureFor(38080);
+        stubFor(get(urlEqualTo(endpoint))
+            .willReturn(WireMock.status(status)
+                .withHeader("Content-Type", "application/json")
+                .withBody(body)));
+    }
+
+    public static void verifyGet(int count, String url) {
+        verify(exactly(count), getRequestedFor(urlEqualTo(url)));
+    }
+
+    private static final WireMockServer wireMockServer = new WireMockServer(38080);
+    private boolean started;
+
+    @Override
+    public void beforeAll(ExtensionContext extensionContext) throws Exception {
+        if (!started) {
+            wireMockServer.start();
+            started = true;
+        }
+    }
+    @Override
+    public void afterEach(ExtensionContext extensionContext) throws Exception {
+        wireMockServer.listAllStubMappings().getMappings().forEach(wireMockServer::removeStub);
+        wireMockServer.findAllUnmatchedRequests().forEach(System.out::println);
+        wireMockServer.resetRequests();
+    }
+
+    @Override
+    public void close() throws Throwable {
+        wireMockServer.stop();
+    }
+
+
+}

src/test/java/eu/ztsh/wymiana/service/NbpServiceTest.java

@@ -0,0 +1,117 @@
+package eu.ztsh.wymiana.service;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import eu.ztsh.wymiana.EntityCreator;
+import eu.ztsh.wymiana.WireMockExtension;
+import eu.ztsh.wymiana.exception.NoDataException;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.EnumSource;
+import org.mockito.Mockito;
+import org.springframework.web.client.RestClient;
+
+import java.time.Clock;
+import java.time.DayOfWeek;
+import java.time.LocalDate;
+import java.time.Month;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+import java.time.temporal.TemporalAdjusters;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+@ExtendWith(WireMockExtension.class)
+class NbpServiceTest {
+
+    private static final ZoneId zone = ZoneId.of("Europe/Warsaw");
+    private static final LocalDate today = LocalDate.of(2024, Month.MAY, 12); // Sunday
+    private static Clock clock;
+    private final DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd");
+    private final RestClient restClient = RestClient.builder().baseUrl(WireMockExtension.baseUrl).build();
+    private NbpService nbpService;
+
+    @BeforeAll
+    static void prepare() {
+        clock = Mockito.mock(Clock.class);
+        Mockito.when(clock.getZone()).thenReturn(zone);
+    }
+
+    @BeforeEach
+    void prepareTest() {
+        nbpService = new NbpService(clock, restClient);
+    }
+
+    @DisplayName("Check if fetch date is calculated properly: weekdays")
+    @ParameterizedTest
+    @EnumSource(value = DayOfWeek.class, names = {"SATURDAY", "SUNDAY"}, mode = EnumSource.Mode.EXCLUDE)
+    void getFetchDateOnWorkingDayTest(DayOfWeek dayOfWeek) {
+        updateClock(dayOfWeek);
+        assertThat(nbpService.getFetchDate()).isEqualTo(
+            switch (dayOfWeek) {
+                case MONDAY -> LocalDate.of(2024, Month.MAY, 6);
+                case TUESDAY -> LocalDate.of(2024, Month.MAY, 7);
+                case WEDNESDAY -> LocalDate.of(2024, Month.MAY, 8);
+                case THURSDAY -> LocalDate.of(2024, Month.MAY, 9);
+                case FRIDAY -> LocalDate.of(2024, Month.MAY, 10);
+                default -> null;
+            }
+        );
+    }
+
+    @DisplayName("Check if fetch date is calculated properly: weekends")
+    @ParameterizedTest
+    @EnumSource(value = DayOfWeek.class, names = {"SATURDAY", "SUNDAY"})
+    void getFetchDateOnWeekendTest(DayOfWeek dayOfWeek) {
+        updateClock(dayOfWeek);
+        assertThat(nbpService.getFetchDate()).isEqualTo(LocalDate.of(2024, Month.MAY, 10));
+    }
+
+    @DisplayName("Fetch rates straight from server")
+    @Test
+    void getWithoutCacheTest() throws JsonProcessingException {
+        var date = dtf.format(updateClock(DayOfWeek.FRIDAY));
+        var url = "/api/exchangerates/rates/c/usd/%s/".formatted(date);
+        WireMockExtension.response(url, 200, new ObjectMapper().writeValueAsString(EntityCreator.rates(date)));
+        try {
+            assertThat(nbpService.getSellRate(EntityCreator.Constants.USD_SYMBOL)).isEqualTo(EntityCreator.Constants.SELL_RATE);
+        } finally {
+            WireMockExtension.verifyGet(1, url);
+        }
+    }
+
+    @DisplayName("Fetch rates from cache")
+    @Test
+    void getWithCacheTest() throws JsonProcessingException {
+        var date = dtf.format(updateClock(DayOfWeek.FRIDAY));
+        var url = "/api/exchangerates/rates/c/usd/%s/".formatted(date);
+        WireMockExtension.response(url, 200, new ObjectMapper().writeValueAsString(EntityCreator.rates(date)));
+        // save to cache
+        assertThat(nbpService.getSellRate(EntityCreator.Constants.USD_SYMBOL)).isEqualTo(EntityCreator.Constants.SELL_RATE);
+        // get from cache
+        assertThat(nbpService.getBuyRate(EntityCreator.Constants.USD_SYMBOL)).isEqualTo(EntityCreator.Constants.BUY_RATE);
+        WireMockExtension.verifyGet(1, url);
+    }
+
+    @DisplayName("Support 404: invalid currency or no data")
+    @Test
+    void getInvalidCurrencyTest() {
+        var date = dtf.format(updateClock(DayOfWeek.FRIDAY));
+        var url = "/api/exchangerates/rates/c/usb/%s/".formatted(date);
+        WireMockExtension.response(url, 404, "404 NotFound - Not Found - Brak danych");
+        assertThatThrownBy(() -> nbpService.getSellRate("usb")).isInstanceOf(NoDataException.class);
+        WireMockExtension.verifyGet(1, url);
+    }
+
+    private LocalDate updateClock(DayOfWeek dayOfWeek) {
+        var date = today.with(TemporalAdjusters.previousOrSame(dayOfWeek));
+        Mockito.when(clock.instant()).thenReturn(date.atStartOfDay(zone).toInstant());
+        return LocalDate.from(date);
+    }
+
+}

src/test/java/eu/ztsh/wymiana/validation/AdultValidatorTest.java

@@ -1,58 +1,42 @@
 package eu.ztsh.wymiana.validation;
 
-import jakarta.validation.ConstraintValidatorContext;
-import org.hibernate.validator.internal.engine.DefaultClockProvider;
-import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
-import org.mockito.Mockito;
 
-import static org.assertj.core.api.Assertions.assertThat;
+class AdultValidatorTest extends ValidatorTest<AdultValidator, String> {
 
-class AdultValidatorTest {
-
-    private static AdultValidator validator;
-    private static ConstraintValidatorContext validatorContext;
-
-    @BeforeAll
-    static void prepare() {
-        validator = new AdultValidator();
-        validatorContext = Mockito.mock(ConstraintValidatorContext.class);
-        Mockito.when(validatorContext.getClockProvider()).thenReturn(DefaultClockProvider.INSTANCE);
+    protected AdultValidatorTest() {
+        super(new AdultValidator());
     }
 
     @Test
     @DisplayName("No digits in PESEL")
     void invalidPatternTest() {
-        assertThat(call("notAPesel")).isFalse();
+        assertThatValidation("notAPesel").isFalse();
     }
 
     @Test
     @DisplayName("Not an adult")
     void notAnAdultTest() {
-        assertThat(call("24242400000")).isFalse();
+        assertThatValidation("24242400000").isFalse();
     }
 
     @Test
     @DisplayName("Adult")
     void adultTest() {
-        assertThat(call("88010100000")).isTrue();
+        assertThatValidation("88010100000").isTrue();
     }
 
     @Test
     @DisplayName("Elderly person")
     void seniorTest() {
-        assertThat(call("00010100000")).isTrue();
+        assertThatValidation("00010100000").isTrue();
     }
 
     @Test
     @DisplayName("Invalid date")
     void notAValidDateTest() {
-        assertThat(call("00919100000")).isFalse();
-    }
-
-    private boolean call(String value) {
-        return validator.isValid(value, validatorContext);
+        assertThatValidation("00919100000").isFalse();
     }
 
 }

src/test/java/eu/ztsh/wymiana/validation/ValidExchangeRequestValidatorTest.java

@@ -0,0 +1,128 @@
+package eu.ztsh.wymiana.validation;
+
+import eu.ztsh.wymiana.EntityCreator;
+import eu.ztsh.wymiana.web.model.CurrencyExchangeRequest;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.util.stream.Stream;
+
+import static eu.ztsh.wymiana.EntityCreator.Constants.*;
+
+class ValidExchangeRequestValidatorTest extends ValidatorTest<ValidExchangeRequestValidator, CurrencyExchangeRequest> {
+
+    protected ValidExchangeRequestValidatorTest() {
+        super(new ValidExchangeRequestValidator());
+    }
+
+    @Test
+    @DisplayName("Valid request with buy value specified")
+    void validRequestWithBuyTest() {
+        assertThatValidation(EntityCreator.exchangeRequest()
+            .from(PLN_SYMBOL)
+            .to(USD_SYMBOL)
+            .toBuy(USD_BUY)
+            .build()).isTrue();
+    }
+
+    @Test
+    @DisplayName("Valid request with sell value specified")
+    void validRequestWithSellTest() {
+        assertThatValidation(EntityCreator.exchangeRequest()
+            .from(PLN_SYMBOL)
+            .to(USD_SYMBOL)
+            .toSell(USD_SELL)
+            .build()).isTrue();
+    }
+
+    @Disabled("Already validated (has field annotation)")
+    @DisplayName("Invalid PESEL value")
+    @ParameterizedTest
+    @MethodSource
+    void invalidPeselTest(String pesel) {
+        assertThatValidation(EntityCreator.exchangeRequest()
+            .pesel(pesel)
+            .from(PLN_SYMBOL)
+            .to(USD_SYMBOL)
+            .toSell(USD_SELL)
+            .build()).isFalse();
+    }
+
+    @Test
+    @DisplayName("From and To have same value")
+    void sameFromToTest() {
+        assertThatValidation(EntityCreator.exchangeRequest()
+            .from(USD_SYMBOL)
+            .to(USD_SYMBOL)
+            .toSell(USD_SELL)
+            .build()).isFalse();
+    }
+
+    @Test
+    @DisplayName("Empty amounts")
+    void emptyBuySellTest() {
+        assertThatValidation(EntityCreator.exchangeRequest()
+            .from(PLN_SYMBOL)
+            .to(USD_SYMBOL)
+            .build()).isFalse();
+    }
+
+    @Disabled("Already validated (has field annotation)")
+    @Test
+    @DisplayName("Empty 'from' value")
+    void emptyFromTest() {
+        assertThatValidation(EntityCreator.exchangeRequest()
+            .to(USD_SYMBOL)
+            .toSell(USD_SELL)
+            .build()).isFalse();
+    }
+
+    @Disabled("Already validated (has field annotation)")
+    @Test
+    @DisplayName("Empty 'to' value")
+    void emptyToTest() {
+        assertThatValidation(EntityCreator.exchangeRequest()
+            .from(PLN_SYMBOL)
+            .toSell(USD_SELL)
+            .build()).isFalse();
+    }
+
+    @Test
+    @DisplayName("Both Buy and Sell params filled in")
+    void bothFilledBuySellTest() {
+        assertThatValidation(EntityCreator.exchangeRequest()
+            .from(PLN_SYMBOL)
+            .to(USD_SYMBOL)
+            .toBuy(USD_BUY)
+            .toSell(USD_SELL)
+            .build()).isFalse();
+    }
+
+    @Test
+    @DisplayName("Negative buy amount value")
+    void negativeBuyAmountTest() {
+        assertThatValidation(EntityCreator.exchangeRequest()
+            .from(PLN_SYMBOL)
+            .to(USD_SYMBOL)
+            .toBuy(-1.0)
+            .build()).isFalse();
+    }
+
+    @Test
+    @DisplayName("Negative sell amount value")
+    void negativeSellAmountTest() {
+        assertThatValidation(EntityCreator.exchangeRequest()
+            .from(PLN_SYMBOL)
+            .to(USD_SYMBOL)
+            .toSell(-1.0)
+            .build()).isFalse();
+    }
+
+    private static Stream<String> invalidPeselTest() {
+        return Stream.of("INVALID", PESEL.replace('6', '7'));
+    }
+
+}

src/test/java/eu/ztsh/wymiana/validation/ValidatorTest.java

@@ -0,0 +1,31 @@
+package eu.ztsh.wymiana.validation;
+
+import jakarta.validation.ConstraintValidator;
+import jakarta.validation.ConstraintValidatorContext;
+import org.assertj.core.api.AbstractBooleanAssert;
+import org.hibernate.validator.internal.engine.DefaultClockProvider;
+import org.junit.jupiter.api.BeforeAll;
+import org.mockito.Mockito;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public abstract class ValidatorTest<V extends ConstraintValidator<?, C>, C> {
+
+    private final V validator;
+    private static ConstraintValidatorContext validatorContext;
+
+    protected ValidatorTest(V validator) {
+        this.validator = validator;
+    }
+
+    @BeforeAll
+    static void prepare() {
+        validatorContext = Mockito.mock(ConstraintValidatorContext.class);
+        Mockito.when(validatorContext.getClockProvider()).thenReturn(DefaultClockProvider.INSTANCE);
+    }
+
+    protected AbstractBooleanAssert<?> assertThatValidation(C value) {
+        return assertThat(validator.isValid(value, validatorContext));
+    }
+
+}