Define ResourceReader interface for reading data from a resource identified by a Resource handle.
Ressolves gh-92.
This commit is contained in:
John Blum
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/*
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* Copyright 2020 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
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* or implied. See the License for the specific language governing
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* permissions and limitations under the License.
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*/
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package org.springframework.geode.core.io;
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import java.nio.ByteBuffer;
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import org.springframework.core.io.Resource;
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import org.springframework.lang.NonNull;
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import org.springframework.lang.Nullable;
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/**
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* Interface (contract) for readers to define the algorithm and strategy for reading data from a {@link Resource},
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* such as by using the {@link Resource Resource's} {@link Resource#getInputStream() InputStream}.
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*
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* @author John Blum
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* @see java.nio.ByteBuffer
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* @see org.springframework.core.io.Resource
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* @since 1.3.1
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*/
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@FunctionalInterface
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@SuppressWarnings("unused")
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public interface ResourceReader {
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/**
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* Reads data from the {@literal non-null} {@link Resource} into a byte array.
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*
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* This method should throw an {@link UnhandledResourceException} if the algorithm and strategy used by this reader
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* is not able to or capable of reading from the {@link Resource} at its location. This allows subsequent readers
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* in a composition to possibly handle the {@link Resource}. Any other {@link Throwable} thrown by this {@code read}
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* method will break the chain of read calls in the composition.
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*
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* @param resource {@link Resource} to read data from.
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* @return a {@literal non-null} byte array containing the data from the {@link Resource}.
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* @see org.springframework.core.io.Resource
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*/
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@NonNull byte[] read(@NonNull Resource resource);
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/**
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* Reads data from the {@literal non-null} {@link Resource} into a {@link ByteBuffer}.
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*
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* @param resource {@link Resource} to read data from.
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* @return a {@literal non-null} {@link ByteBuffer} containing the data from the {@link Resource}.
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* @see org.springframework.core.io.Resource
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* @see java.nio.ByteBuffer
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* @see #read(Resource)
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*/
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default @NonNull ByteBuffer readIntoByteBuffer(@NonNull Resource resource) {
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return ByteBuffer.wrap(read(resource));
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}
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/**
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* Composes this {@link ResourceReader} with the given {@link ResourceReader}
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* using the {@literal Composite Software Design Pattern}.
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*
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* @param reader {@link ResourceReader} to compose with this reader.
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* @return a composite {@link ResourceReader} composed of this {@link ResourceReader}
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* and the given {@link ResourceReader}. If the given {@link ResourceReader} is {@literal null},
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* then this {@link ResourceReader} is returned.
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* @see <a href="https://en.wikipedia.org/wiki/Composite_pattern">Compsite Software Design Pattern</a>
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* @see ResourceReader
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*/
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default @NonNull ResourceReader thenReadFrom(@Nullable ResourceReader reader) {
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return reader == null ? this
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: resource -> {
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try {
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return this.read(resource);
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}
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catch (UnhandledResourceException ignore) {
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return reader.read(resource);
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}
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};
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}
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}
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@@ -0,0 +1,141 @@
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/*
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* Copyright 2020 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
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* or implied. See the License for the specific language governing
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* permissions and limitations under the License.
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*/
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package org.springframework.geode.core.io;
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import static org.assertj.core.api.Assertions.assertThat;
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import static org.mockito.ArgumentMatchers.any;
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import static org.mockito.ArgumentMatchers.eq;
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import static org.mockito.Mockito.doCallRealMethod;
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import static org.mockito.Mockito.doReturn;
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import static org.mockito.Mockito.doThrow;
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import static org.mockito.Mockito.mock;
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import static org.mockito.Mockito.never;
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import static org.mockito.Mockito.times;
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import static org.mockito.Mockito.verify;
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import static org.mockito.Mockito.verifyNoInteractions;
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import java.nio.ByteBuffer;
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import org.junit.Test;
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import org.springframework.core.io.Resource;
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/**
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* Unit Tests for {@link ResourceReader}.
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*
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* @author John Blum
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* @see java.nio.ByteBuffer
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* @see org.junit.Test
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* @see org.mockito.Mockito
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* @see org.springframework.core.io.Resource
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* @see org.springframework.geode.core.io.ResourceReader
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* @since 1.3.1
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*/
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public class ResourceReaderUnitTests {
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@Test
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public void readIntoByteBufferCallsRead() {
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byte[] array = { (byte) 0xCA, (byte) 0xFE, (byte) 0xBA, (byte) 0xBE };
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Resource mockResource = mock(Resource.class);
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ResourceReader mockResourceReader = mock(ResourceReader.class);
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doReturn(array).when(mockResourceReader).read(eq(mockResource));
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doCallRealMethod().when(mockResourceReader).readIntoByteBuffer(any());
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ByteBuffer byteBuffer = mockResourceReader.readIntoByteBuffer(mockResource);
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assertThat(byteBuffer).isNotNull();
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assertThat(byteBuffer.array()).isEqualTo(array);
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verify(mockResourceReader, times(1)).read(eq(mockResource));
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verifyNoInteractions(mockResource);
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}
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@Test
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public void thenReadFromNullReturnsThis() {
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ResourceReader mockResourceReader = mock(ResourceReader.class);
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doCallRealMethod().when(mockResourceReader).thenReadFrom(any());
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assertThat(mockResourceReader.thenReadFrom(null)).isEqualTo(mockResourceReader);
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}
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@Test
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public void thenReadFromResourceReaderReturnsComposite() {
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ResourceReader thisMockResourceReader = mock(ResourceReader.class, "this");
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ResourceReader thatMockResourceReader = mock(ResourceReader.class, "that");
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doCallRealMethod().when(thisMockResourceReader).thenReadFrom(any());
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ResourceReader composite = thisMockResourceReader.thenReadFrom(thatMockResourceReader);
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assertThat(composite).isNotNull();
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assertThat(composite).isNotEqualTo(thisMockResourceReader);
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assertThat(composite).isNotEqualTo(thatMockResourceReader);
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}
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@Test
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public void thenReadFromResourceReaderReadsFromThis() {
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byte[] array = { (byte) 0xBA, (byte) 0xBE };
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Resource mockResource = mock(Resource.class);
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ResourceReader thisMockResourceReader = mock(ResourceReader.class, "this");
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ResourceReader thatMockResourceReader = mock(ResourceReader.class, "that");
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doCallRealMethod().when(thisMockResourceReader).thenReadFrom(any());
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doReturn(array).when(thisMockResourceReader).read(eq(mockResource));
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ResourceReader composite = thisMockResourceReader.thenReadFrom(thatMockResourceReader);
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assertThat(composite).isNotNull();
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assertThat(composite.read(mockResource)).isEqualTo(array);
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verify(thisMockResourceReader, times(1)).read(eq(mockResource));
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verify(thatMockResourceReader, never()).read(any());
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verifyNoInteractions(mockResource);
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}
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@Test
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public void thenReadFromResourceReaderReadsFromThat() {
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byte[] array = { (byte) 0xFA, (byte) 0xDE };
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Resource mockResource = mock(Resource.class);
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ResourceReader thisMockResourceReader = mock(ResourceReader.class, "this");
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ResourceReader thatMockResourceReader = mock(ResourceReader.class, "that");
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doCallRealMethod().when(thisMockResourceReader).thenReadFrom(any());
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doThrow(new UnhandledResourceException("TEST")).when(thisMockResourceReader).read(eq(mockResource));
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doReturn(array).when(thatMockResourceReader).read(eq(mockResource));
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ResourceReader composite = thisMockResourceReader.thenReadFrom(thatMockResourceReader);
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assertThat(composite).isNotNull();
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assertThat(composite.read(mockResource)).isEqualTo(array);
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verify(thisMockResourceReader, times(1)).read(eq(mockResource));
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verify(thatMockResourceReader, times(1)).read(eq(mockResource));
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verifyNoInteractions(mockResource);
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}
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}
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