issue-299: split argument value when argument type is array

Jackson is able to convert an array of String values to an
array of other Java types. However, it does not parse a raw
String and split it if it is intended to be mapped to an array.

This commit prepares the data for Jackson by splitting the
value of `RandomizerArgument` when its type is an array.

NB: The goal is to cover simple use cases of comma separated
values like reported in #299. There is no plan to make this
feature support custom separator, date format, number format, etc.

random-beans/src/main/java/io/github/benas/randombeans/util/ReflectionUtils.java

@@ -466,7 +466,14 @@ private static Object[] convertArguments(final RandomizerArgument[] declaredArgu
         int numberOfArguments = declaredArguments.length;
         Object[] arguments = new Object[numberOfArguments];
         for (int i = 0; i < numberOfArguments; i++) {
-            arguments[i] = objectMapper.convertValue(declaredArguments[i].value(), declaredArguments[i].type());
+            Class<?> type = declaredArguments[i].type();
+            String argument = declaredArguments[i].value();
+            Object value = argument;
+            // issue 299: if argument type is array, split values before conversion
+            if (type.isArray()) {
+                value = Stream.of(argument.split(",")).map(String::trim).toArray();
+            }
+            arguments[i] = objectMapper.convertValue(value, type);
         }
         return arguments;
     }

random-beans/src/test/java/io/github/benas/randombeans/RandomizerAnnotationTest.java

@@ -27,6 +27,10 @@
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
+import io.github.benas.randombeans.annotation.RandomizerArgument;
+import io.github.benas.randombeans.api.EnhancedRandom;
+import io.github.benas.randombeans.randomizers.AbstractRandomizer;
+import lombok.Data;
 import org.junit.jupiter.api.Test;
 
 import io.github.benas.randombeans.api.ObjectGenerationException;
@@ -46,6 +50,59 @@ public void shouldThrowObjectGenerationExceptionWhenRandomizerUsedInRandomizerAn
         assertThatThrownBy(() -> aNewEnhancedRandom().nextObject(Bar.class)).isInstanceOf(ObjectGenerationException.class);
     }
 
+
+    @Test
+    void testRandomizerArgumentAsArray() {
+        Person person = EnhancedRandom.random(Person.class);
+
+        assertThat(person.getName()).isIn("foo", "bar");
+        assertThat(person.getAge()).isIn(1, 2, 3);
+    }
+
+    @Data
+    static class Person {
+
+        @io.github.benas.randombeans.annotation.Randomizer(value = MyStringRandomizer.class, args = {
+                @RandomizerArgument(value = "foo, bar", type = String[].class)
+        })
+        private String name;
+
+        @io.github.benas.randombeans.annotation.Randomizer(value = MyNumbersRandomizer.class, args = {
+                @RandomizerArgument(value = "1, 2, 3", type = Integer[].class)
+        })
+        private int age;
+    }
+
+    public static class MyStringRandomizer extends AbstractRandomizer<String> {
+
+        private String[] words;
+
+        public MyStringRandomizer(String[] words) {
+            this.words = words;
+        }
+
+        @Override
+        public String getRandomValue() {
+            int randomIndex = random.nextInt(words.length);
+            return words[randomIndex];
+        }
+    }
+
+    public static class MyNumbersRandomizer extends AbstractRandomizer<Integer> {
+
+        private Integer[] numbers;
+
+        public MyNumbersRandomizer(Integer[] numbers) {
+            this.numbers = numbers;
+        }
+
+        @Override
+        public Integer getRandomValue() {
+            int randomIndex = random.nextInt(numbers.length);
+            return numbers[randomIndex];
+        }
+    }
+
     private class Bar {
         @io.github.benas.randombeans.annotation.Randomizer(RandomizerWithoutDefaultConstrcutor.class)
         private String name;