Failing test With "Duplicate in union:com.fasterxml.jackson.dataformat.avro.schema.RecordVisitor_schemaCreationTest.Cat"

Author: MichalFoksa

avro/src/test/java/com/fasterxml/jackson/dataformat/avro/schema/PolymorphicTypeAnnotations_failingTest.java

@@ -0,0 +1,63 @@
+package com.fasterxml.jackson.dataformat.avro.schema;
+
+import com.fasterxml.jackson.annotation.JsonSubTypes;
+import com.fasterxml.jackson.databind.JsonMappingException;
+import com.fasterxml.jackson.dataformat.avro.AvroMapper;
+import org.apache.avro.Schema;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class PolymorphicTypeAnnotations_failingTest {
+
+    private static final AvroMapper MAPPER = AvroMapper.builder().build();
+    // it is easier maintain string schema representation when namespace is constant, rather than being inferend from this class package name
+    private static final String TEST_NAMESPACE = "test";
+
+    @JsonSubTypes({
+            @JsonSubTypes.Type(value = AbstractMammal.class),
+            @JsonSubTypes.Type(value = Cat.class),
+            // Cat being twice in @JsonSubTypes causes Duplicate in union:com.fasterxml.jackson.dataformat.avro.schema.RecordVisitor_schemaCreationTest.Cat"
+            @JsonSubTypes.Type(value = Cat.class),
+            @JsonSubTypes.Type(value = Dog.class),
+    })
+    private interface Animal {
+    }
+
+    @JsonSubTypes({
+            @JsonSubTypes.Type(value = Cat.class),
+            @JsonSubTypes.Type(value = Dog.class),
+    })
+    private static abstract class AbstractMammal implements Animal {
+        public int legs;
+    }
+
+    static class Cat extends AbstractMammal {
+        public String color;
+    }
+
+    static class Dog extends AbstractMammal {
+        public int size;
+    }
+
+    // It fails cause Cat and Dog are references twice as subTypes and this gets  twice into a union
+    // Easiest way to reproduce it is to add class twice into @JsonSubTypes
+    // Causes Duplicate in union:com.fasterxml.jackson.dataformat.avro.schema.RecordVisitor_schemaCreationTest.Cat"
+    @Test
+    public void class_is_referenced_twice_in_hierarchy_test() throws JsonMappingException {
+        // GIVEN
+        final Schema catSchema = MAPPER.schemaFor(Cat.class).getAvroSchema();
+        final Schema dogSchema = MAPPER.schemaFor(Dog.class).getAvroSchema();
+
+        // WHEN
+        Schema actualSchema = MAPPER.schemaFor(Animal.class).getAvroSchema();
+
+        System.out.println("Animal schema:\n" + actualSchema.toString(true));
+
+        // THEN
+        assertThat(actualSchema.getType()).isEqualTo(Schema.Type.UNION);
+        // Because Animal is interface and Mammal is abstract, they are not expected to be among types in union
+        assertThat(actualSchema.getTypes()).containsExactlyInAnyOrder(catSchema, dogSchema);
+    }
+
+}