Merge pull request #3558 from nguyennamthai/BAEL-1515

Initial commit for BAEL-1515

testing-modules/testing/pom.xml

@@ -154,6 +154,16 @@
                     </execution>
                 </executions>
             </plugin>
+            <plugin>
+                <groupId>org.assertj</groupId>
+                <artifactId>assertj-assertions-generator-maven-plugin</artifactId>
+                <version>${assertj-generator.version}</version>
+                <configuration>
+                    <classes>
+                        <param>com.baeldung.testing.assertj.custom.Person</param>
+                    </classes>
+                </configuration>
+            </plugin>
         </plugins>
     </build>
 
@@ -164,6 +174,7 @@
         <guava.version>21.0</guava.version>
         <assertj-guava.version>3.1.0</assertj-guava.version>
         <assertj-core.version>3.6.1</assertj-core.version>
+        <assertj-generator.version>2.1.0</assertj-generator.version>
         <truth.version>0.32</truth.version>
         <jUnitParams.version>1.1.0</jUnitParams.version>
         <jgotesting.version>0.12</jgotesting.version>

testing-modules/testing/src/main/java/com/baeldung/testing/assertj/custom/Person.java

@@ -0,0 +1,32 @@
+package com.baeldung.testing.assertj.custom;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Person {
+    private String fullName;
+    private int age;
+    private List<String> nicknames;
+
+    public Person(String fullName, int age) {
+        this.fullName = fullName;
+        this.age = age;
+        this.nicknames = new ArrayList<>();
+    }
+
+    public void addNickname(String nickname) {
+        nicknames.add(nickname);
+    }
+
+    public String getFullName() {
+        return fullName;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public List<String> getNicknames() {
+        return nicknames;
+    }
+}

testing-modules/testing/src/test/java/com/baeldung/testing/assertj/custom/AssertJCustomAssertionsUnitTest.java

@@ -0,0 +1,44 @@
+package com.baeldung.testing.assertj.custom;
+
+import static com.baeldung.testing.assertj.custom.Assertions.assertThat;
+import static org.junit.Assert.fail;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+public class AssertJCustomAssertionsUnitTest {
+    @Rule
+    public ExpectedException thrown = ExpectedException.none();
+
+    @Test
+    public void whenPersonNameMatches_thenCorrect() {
+        Person person = new Person("John Doe", 20);
+        assertThat(person).hasFullName("John Doe");
+    }
+
+    @Test
+    public void whenPersonAgeLessThanEighteen_thenNotAdult() {
+        Person person = new Person("Jane Roe", 16);
+
+        try {
+            assertThat(person).isAdult();
+            fail();
+        } catch (AssertionError e) {
+            org.assertj.core.api.Assertions.assertThat(e).hasMessage("Expected person to be adult");
+        }
+    }
+
+    @Test
+    public void whenPersonDoesNotHaveAMatchingNickname_thenIncorrect() {
+        Person person = new Person("John Doe", 20);
+        person.addNickname("Nick");
+
+        try {
+            assertThat(person).hasNickname("John");
+            fail();
+        } catch (AssertionError e) {
+            org.assertj.core.api.Assertions.assertThat(e).hasMessage("Expected person to have nickname John");
+        }
+    }
+}

testing-modules/testing/src/test/java/com/baeldung/testing/assertj/custom/Assertions.java

@@ -0,0 +1,9 @@
+package com.baeldung.testing.assertj.custom;
+
+public class Assertions {
+    public static PersonAssert assertThat(Person actual) {
+        return new PersonAssert(actual);
+    }
+
+    // static factory methods of other assertion classes
+}

testing-modules/testing/src/test/java/com/baeldung/testing/assertj/custom/PersonAssert.java

@@ -0,0 +1,38 @@
+package com.baeldung.testing.assertj.custom;
+
+import org.assertj.core.api.AbstractAssert;
+
+public class PersonAssert extends AbstractAssert<PersonAssert, Person> {
+
+    public PersonAssert(Person actual) {
+        super(actual, PersonAssert.class);
+    }
+
+    public static PersonAssert assertThat(Person actual) {
+        return new PersonAssert(actual);
+    }
+
+    public PersonAssert hasFullName(String fullName) {
+        isNotNull();
+        if (!actual.getFullName().equals(fullName)) {
+            failWithMessage("Expected person to have full name %s but was %s", fullName, actual.getFullName());
+        }
+        return this;
+    }
+
+    public PersonAssert isAdult() {
+        isNotNull();
+        if (actual.getAge() < 18) {
+            failWithMessage("Expected person to be adult");
+        }
+        return this;
+    }
+
+    public PersonAssert hasNickname(String nickName) {
+        isNotNull();
+        if (!actual.getNicknames().contains(nickName)) {
+            failWithMessage("Expected person to have nickname %s", nickName);
+        }
+        return this;
+    }
+}