An Introduction to Vavr's Validation API - Alejandro Gervasio | alejandro.gervasio@gmail.com (#2526)

* Initial Commit

* Refactored Application class

* Refactored Application class

* Refactored Application class

* Refactored User class

* Added ValidationTest class

* Reorganized imports in ValidatorTest class

* Reformatted source code

* Reformatted source code

vavr/vavr-validation/src/main/java/com/baeldung/vavrvalidation/application/Application.java

@@ -0,0 +1,17 @@
+package com.baeldung.vavrvalidation.application;
+
+import com.baeldung.vavrvalidation.model.User;
+import com.baeldung.vavrvalidation.validator.UserValidator;
+import io.vavr.collection.Seq;
+import io.vavr.control.Validation;
+
+public class Application {
+
+    public static void main(String[] args) {
+        
+        UserValidator userValidator = new UserValidator();
+        Validation<Seq<String>, User> validation = userValidator.validateUser("John", "john@domain.com");
+        
+        // process validation results here
+	}	
+}

vavr/vavr-validation/src/main/java/com/baeldung/vavrvalidation/model/User.java

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+package com.baeldung.vavrvalidation.model;
+
+public class User {
+    private String name;
+    private String email;
+    
+    public User(String name, String email) {
+        this.name = name;
+        this.email = email;
+    }
+    
+    @Override
+    public String toString() {
+        return "User [name=" + name + ", email=" + email + "]";
+    }
+    
+    // standard setters and getters
+}

vavr/vavr-validation/src/main/java/com/baeldung/vavrvalidation/validator/UserValidator.java

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+package com.baeldung.vavrvalidation.validator;
+
+import com.baeldung.vavrvalidation.model.User;
+import io.vavr.collection.CharSeq;
+import io.vavr.collection.Seq;
+import io.vavr.control.Validation;
+
+public class UserValidator {
+    
+    private static final String NAME_PATTERN = "^[a-zA-Z0-9]+$";
+    private static final String NAME_ERROR = "Name contains invalid characters";
+    private static final String EMAIL_PATTERN =
+        "^[_A-Za-z0-9-\\+]+(\\.[_A-Za-z0-9-]+)*@"
+          + "[A-Za-z0-9-]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$";
+    private static final String EMAIL_ERROR = "Email must be a well-formed email address";
+    
+	public Validation<Seq<String>, User> validateUser(String name, String email) {
+        return Validation
+          .combine(validateField(name, NAME_PATTERN, NAME_ERROR)
+              ,validateField(email, EMAIL_PATTERN, EMAIL_ERROR))
+                .ap(User::new);
+    }
+    
+    private Validation<String, String> validateField(String field, String pattern, String error) {
+        return CharSeq.of(field).replaceAll(pattern, "").transform(seq -> seq.isEmpty()
+          ? Validation.valid(field) 
+            : Validation.invalid(error));
+    }
+}

vavr/vavr-validation/src/test/java/com/baeldung/vavrvalidation/validator/UserValidatorTest.java

@@ -0,0 +1,23 @@
+package com.baeldung.vavrvalidation.validator;
+
+import static org.junit.Assert.*;
+import static org.hamcrest.CoreMatchers.instanceOf;
+import org.junit.Test;
+import com.baeldung.vavrvalidation.validator.UserValidator;
+import io.vavr.control.Validation.Invalid;
+import io.vavr.control.Validation.Valid;
+
+public class UserValidatorTest {
+    
+    @Test
+    public void givenValidUserParams_whenValidated_thenInstanceOfValid() {
+        UserValidator userValidator = new UserValidator();
+        assertThat(userValidator.validateUser("John", "john@domain.com"), instanceOf(Valid.class));
+    }
+    
+    @Test
+    public void givenInvalidUserParams_whenValidated_thenInstanceOfInvalid() {
+        UserValidator userValidator = new UserValidator();
+        assertThat(userValidator.validateUser("John", "no-email"), instanceOf(Invalid.class));
+    }
+}

vavr/vavr-validation/src/test/java/com/baeldung/vavrvalidation/validator/ValidationTest.java

@@ -0,0 +1,68 @@
+package com.baeldung.vavrvalidation.validator;
+
+import static org.hamcrest.CoreMatchers.*;
+import static org.junit.Assert.*;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import com.baeldung.vavrvalidation.model.User;
+import io.vavr.collection.Seq;
+import io.vavr.control.Either.Right;
+import io.vavr.control.Validation.Invalid;
+import io.vavr.control.Validation.Valid;
+
+public class ValidationTest {
+	
+    private static UserValidator userValidator;
+    
+    @BeforeClass
+    public static void setUpUserValidatorInstance() {
+        userValidator = new UserValidator();
+    }
+    
+    @AfterClass
+    public static void teardownUserValidatorInstance() {
+        userValidator = null;
+    }
+    
+    @Test
+    public void givenInvalidUserParams_whenValidated_thenInvalidInstance() {
+        assertThat(userValidator.validateUser("John", "no-email"), instanceOf(Invalid.class));
+    }
+    
+    @Test
+    public void givenValidUserParams_whenValidated_thenValidInstance() {
+        assertThat(userValidator.validateUser("John", "john@domain.com"), instanceOf(Valid.class));
+    }
+    
+    @Test
+    public void givenInvalidUserParams_whenValidated_thenTrueWithIsInvalidMethod() {
+        assertTrue(userValidator.validateUser("John", "no-email").isInvalid());
+    }
+
+    @Test
+    public void givenValidUserParams_whenValidated_thenTrueWithIsValidMethod() {
+        assertTrue(userValidator.validateUser("John", "john@domain.com").isValid());
+    }
+    
+    @Test
+	public void givenInValidUserParams_withGetErrorMethod_thenGetErrorMessages() {
+        assertEquals("Name contains invalid characters, Email must be a well-formed email address", userValidator.validateUser(" ", "no-email")
+          .getError().intersperse(", ").fold("", String::concat));
+    }
+    
+    @Test
+    public void givenValidUserParams_withGetMethod_thenGetUserInstance() {
+        assertThat(userValidator.validateUser("John", "john@domain.com").get(), instanceOf(User.class));
+    }
+    
+    @Test
+    public void givenValidUserParams_withtoEitherMethod_thenRightInstance() {
+        assertThat(userValidator.validateUser("John", "john@domain.com").toEither(), instanceOf(Right.class));
+    }
+    
+    @Test
+    public void givenValidUserParams_withFoldMethodWithListlengthUserHashCode_thenEqualstoParamsLength() {
+        assertEquals(2, (int) userValidator.validateUser(" ", " ").fold(Seq::length, User::hashCode));
+    }
+}