Add abstract base class implementing the ObjectArrayToJsonConverter interface to encapsulate operation common to all implementations.

The abstract base class provides convert methods to convert arrays, Iterables and Map.values(). Additionally it contains support to configure the ObjectToJsonConverter used to convert individual Objects into JSON.

Resolves gh-67.

spring-geode/src/test/java/org/springframework/geode/data/json/converter/AbstractObjectArrayToJsonConverterUnitTests.java

@@ -0,0 +1,147 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+package org.springframework.geode.data.json.converter;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.ArgumentMatchers.isA;
+import static org.mockito.Mockito.doCallRealMethod;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Map;
+
+import org.junit.Test;
+import org.mockito.ArgumentMatchers;
+
+import example.app.crm.model.Customer;
+
+/**
+ * Unit Tests for {@link AbstractObjectArrayToJsonConverter}.
+ *
+ * @author John Blum
+ * @see org.junit.Test
+ * @see org.mockito.Mockito
+ * @see org.springframework.geode.data.json.converter.AbstractObjectArrayToJsonConverter
+ * @since 1.3.0
+ */
+public class AbstractObjectArrayToJsonConverterUnitTests {
+
+	@Test
+	public void convertIterable() {
+
+		Customer jonDoe = Customer.newCustomer(1L, "Jon Doe");
+		Customer janeDoe = Customer.newCustomer(2L, "Jane Doe");
+
+		Iterable<Object> iterable = Arrays.asList(jonDoe, janeDoe);
+
+		String jonDoeJson = "{ \"name\": \"Jon Doe\" }";
+		String janeDoeJson = "{ \"name\": \"Jane Doe\" }";
+		String json = String.format("[%s, %s]", jonDoeJson, janeDoeJson);
+
+		ObjectToJsonConverter mockConverter = mock(ObjectToJsonConverter.class);
+
+		doReturn(jonDoeJson).when(mockConverter).convert(eq(jonDoe));
+		doReturn(janeDoeJson).when(mockConverter).convert(eq(janeDoe));
+
+		AbstractObjectArrayToJsonConverter converter = mock(AbstractObjectArrayToJsonConverter.class);
+
+		doCallRealMethod().when(converter).convert(ArgumentMatchers.<Iterable<Object>>any());
+		doReturn(mockConverter).when(converter).getObjectToJsonConverter();
+
+		assertThat(converter.convert(iterable)).isEqualTo(json);
+
+		verify(converter, times(1)).getObjectToJsonConverter();
+		verify(mockConverter, times(1)).convert(eq(jonDoe));
+		verify(mockConverter, times(1)).convert(eq(janeDoe));
+	}
+
+	@Test
+	public void convertEmptyIterable() {
+
+		String json = "[]";
+
+		AbstractObjectArrayToJsonConverter converter = mock(AbstractObjectArrayToJsonConverter.class);
+
+		doCallRealMethod().when(converter).convert(ArgumentMatchers.<Iterable<Object>>any());
+
+		assertThat(converter.convert(Collections.emptySet())).isEqualTo(json);
+
+		verify(converter, times(1)).getObjectToJsonConverter();
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void convertNullIterable() {
+
+		AbstractObjectArrayToJsonConverter converter = mock(AbstractObjectArrayToJsonConverter.class);
+
+		doCallRealMethod().when(converter).convert(ArgumentMatchers.<Iterable<Object>>any());
+
+		try {
+			converter.convert((Iterable<Object>) null);
+		}
+		catch (IllegalArgumentException expected) {
+
+			assertThat(expected).hasMessage("Iterable must not be null");
+			assertThat(expected).hasNoCause();
+
+			throw expected;
+		}
+		finally {
+			verify(converter, never()).getObjectToJsonConverter();
+		}
+	}
+
+	@Test
+	@SuppressWarnings("unchecked")
+	public void convertMap() {
+
+		String json = "[{ ... }, { ... }]";
+
+		Map<?, ?> mockMap = mock(Map.class);
+
+		AbstractObjectArrayToJsonConverter converter = mock(AbstractObjectArrayToJsonConverter.class);
+
+		doCallRealMethod().when(converter).convert(any(Map.class));
+		doReturn(json).when(converter).convert(any(Iterable.class));
+
+		assertThat(converter.convert(mockMap)).isEqualTo(json);
+
+		verify(converter, times(1)).convert(eq(Collections.emptyList()));
+	}
+
+	@Test
+	@SuppressWarnings({ "rawtypes", "unchecked" })
+	public void convertMapIsNullSafe() {
+
+		String json = "[]";
+
+		AbstractObjectArrayToJsonConverter converter = mock(AbstractObjectArrayToJsonConverter.class);
+
+		doCallRealMethod().when(converter).convert(ArgumentMatchers.<Map>any());
+		doReturn(json).when(converter).convert(any(Iterable.class));
+
+		assertThat(converter.convert((Map) null)).isEqualTo(json);
+
+		verify(converter, times(1)).convert(isA(Iterable.class));
+	}
+}