added constraint on class api to ValidatorBuilder

src/main/java/am/ik/yavi/builder/ValidatorBuilder.java

@@ -15,29 +15,6 @@
  */
 package am.ik.yavi.builder;
 
-import java.math.BigDecimal;
-import java.math.BigInteger;
-import java.time.Instant;
-import java.time.LocalDate;
-import java.time.LocalDateTime;
-import java.time.LocalTime;
-import java.time.OffsetDateTime;
-import java.time.Year;
-import java.time.YearMonth;
-import java.time.ZonedDateTime;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.Deque;
-import java.util.LinkedHashMap;
-import java.util.LinkedList;
-import java.util.List;
-import java.util.Map;
-import java.util.function.Consumer;
-import java.util.function.Function;
-import java.util.function.Predicate;
-import java.util.function.Supplier;
-
 import am.ik.yavi.constraint.BigDecimalConstraint;
 import am.ik.yavi.constraint.BigIntegerConstraint;
 import am.ik.yavi.constraint.BooleanConstraint;
@@ -111,6 +88,29 @@
 import am.ik.yavi.meta.YearMonthConstraintMeta;
 import am.ik.yavi.meta.ZonedDateTimeConstraintMeta;
 
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.time.Instant;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.LocalTime;
+import java.time.OffsetDateTime;
+import java.time.Year;
+import java.time.YearMonth;
+import java.time.ZonedDateTime;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Deque;
+import java.util.LinkedHashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Consumer;
+import java.util.function.Function;
+import java.util.function.Predicate;
+import java.util.function.Supplier;
+
 public class ValidatorBuilder<T> implements Cloneable {
 	private static final String DEFAULT_SEPARATOR = ".";
 
@@ -732,6 +732,33 @@ public ValidatorBuilder<T> _doubleArray(ToDoubleArray<T> f, String name,
 		return this.constraint(f, name, c, DoubleArrayConstraint::new);
 	}
 
+	/**
+	 * @since 0.14.0
+	 */
+	public <C extends T> ValidatorBuilder<T> constraintOnClass(Class<C> clazz,
+			Validator<C> cValidator) {
+		Validator<T> TValidator = new ValidatorBuilder<T>()
+				.nest(clazz::cast, clazz.getName(), cValidator).build();
+
+		return constraintOnCondition(getClassConstraintCondition(clazz), TValidator);
+	}
+
+	/**
+	 * @since 0.14.0
+	 */
+	public <C extends T> ValidatorBuilder<T> constraintOnClass(Class<C> clazz,
+			ValidatorBuilderConverter<C> converter) {
+		ValidatorBuilderConverter<T> tConverter = tValidatorBuilder -> tValidatorBuilder
+				.nest(clazz::cast, clazz.getName(), converter);
+
+		return constraintOnCondition(getClassConstraintCondition(clazz), tConverter);
+	}
+
+	private <C extends T> ConstraintCondition<T> getClassConstraintCondition(
+			Class<C> classCondition) {
+		return (t, c) -> classCondition.isInstance(t);
+	}
+
 	/**
 	 * @since 0.11.0
 	 */

src/test/java/am/ik/yavi/core/ConstraintOnClassTest.java

@@ -0,0 +1,71 @@
+package am.ik.yavi.core;
+
+import am.ik.yavi.User;
+import am.ik.yavi.builder.ValidatorBuilder;
+import am.ik.yavi.constraint.CharSequenceConstraint;
+import org.junit.jupiter.api.TestInstance;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.util.function.Function;
+import java.util.stream.Stream;
+
+import static com.google.common.truth.Truth.assertThat;
+
+public class ConstraintOnClassTest {
+
+	@ParameterizedTest
+	@MethodSource("provideValidators")
+	void testConstraintOnConditionClass(Validator<User> validator) {
+		User validAdmin = new Admin("admin123", "admin@gmail", 27, "yavi123");
+		User invalidAdmin = new Admin("Niraz", "niraz@gmail", 23, "user");
+
+		assertThat(validator.validate(validAdmin).isValid()).isTrue();
+		assertThat(validator.validate(invalidAdmin).isValid()).isFalse();
+	}
+
+	@ParameterizedTest
+	@MethodSource("provideValidators")
+	void testConstraintOnNonConditionClass(Validator<User> validator) {
+		User validUser = new User("Rawad", "rawad@gmail", 25);
+		User invalidUser = new User("Almog", "almog@gmail", 19);
+
+		assertThat(validator.validate(validUser).isValid()).isTrue();
+		assertThat(validator.validate(invalidUser).isValid()).isFalse();
+	}
+
+	static Stream<Arguments> provideValidators() {
+		ValidatorBuilder<User> userValidatorBuilder = ValidatorBuilder.of(User.class)
+				.constraint(User::getAge, "age", c -> c.greaterThan(20));
+		Function<CharSequenceConstraint<Admin, String>, CharSequenceConstraint<Admin, String>> startsWithAdmin = (
+				CharSequenceConstraint<Admin, String> c) -> c.startsWith("yavi");
+
+		return Stream
+				.of(Arguments.of(new ValidatorBuilder<>(userValidatorBuilder)
+						.constraintOnClass(Admin.class,
+								ValidatorBuilder.of(Admin.class)
+										.constraint(Admin::getGroup, "group",
+												startsWithAdmin)
+										.build())
+						.build()), Arguments
+								.of(new ValidatorBuilder<>(userValidatorBuilder)
+										.constraintOnClass(Admin.class,
+												b -> b.constraint(Admin::getGroup,
+														"group", startsWithAdmin))
+										.build()));
+	}
+
+	private static class Admin extends User {
+		private String group;
+
+		public Admin(String name, String email, int age, String group) {
+			super(name, email, age);
+			this.group = group;
+		}
+
+		public String getGroup() {
+			return group;
+		}
+	}
+}