Add [+UserDeserializationTest+]

src/test/java/UserDeserializationTest.java

@@ -0,0 +1,72 @@
+import com.fasterxml.jackson.annotation.JsonAlias;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.Test;
+
+import static java.util.Objects.hash;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+
+public class UserDeserializationTest {
+
+    public static class User {
+        private String username;
+        private int age;
+
+        public String getUsername() {
+            return username;
+        }
+
+        public void setUsername(String username) {
+            this.username = username;
+        }
+
+        public int getAge() {
+            return age;
+        }
+
+        public void setAge(int age) {
+            this.age = age;
+        }
+
+        @Override
+        public boolean equals(final Object o) {
+            return this == o
+                || (o instanceof User
+                 && hashCode() == o.hashCode());
+        }
+
+        @Override
+        public int hashCode() {
+            return hash(getUsername(),
+                        getAge());
+        }
+    }
+
+    abstract static class UserMixin {
+        public static final String USER_NAME = "user_name";
+        @JsonProperty
+        @JsonAlias(USER_NAME)
+        abstract void setUsername(String username);
+    }
+
+    @Test
+    public void testUserDeserializationWithSingleObjectMapper() throws Exception {
+
+        ObjectMapper mapper = new ObjectMapper();
+        mapper.addMixIn(User.class, UserMixin.class);
+
+        String json1 = "{\"username\": \"Bob\", \"age\": 25}";
+        assertThat(json1).doesNotContain(UserMixin.USER_NAME);
+
+        String json2 = json1.replace("username", UserMixin.USER_NAME);
+        assertThat(json2).contains(UserMixin.USER_NAME);
+
+        assertNotEquals(json1, json2);
+
+        User user1 = mapper.readValue(json1, User.class);
+        User user2 = mapper.readValue(json2, User.class);
+        assertEquals(user1, user2);
+    }
+}