Add mockito based mock testing for ReadBufferDataHandle

Author: gab1one

pom.xml

@@ -184,6 +184,11 @@ Konstanz, and KNIME GmbH.</license.copyrightOwners>
 			<artifactId>junit</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.mockito</groupId>
+			<artifactId>mockito-core</artifactId>
+			<scope>test</scope>
+			</dependency>
 	</dependencies>
 
 	<build>

src/test/java/org/scijava/io/handle/ReadBufferDataHandleMockTest.java

@@ -0,0 +1,128 @@
+
+package org.scijava.io.handle;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.AdditionalMatchers.aryEq;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyLong;
+
+import org.scijava.io.location.DummyLocation;
+import org.scijava.io.location.Location;
+
+import static org.mockito.Mockito.*;
+
+import java.io.IOException;
+
+public class ReadBufferDataHandleMockTest {
+
+	private DataHandle<Location> mock;
+	private AbstractDataHandle<Location> buf;
+	private byte[] byteArrayLen10;
+	private long innerOffset;
+
+	@SuppressWarnings("unchecked")
+	@Before
+	public void setup() throws IOException {
+		innerOffset = 0l;
+		mock = mock(DataHandle.class);
+
+		// needed to get around type checking in AbstractWrapperPlugin
+		when(mock.get()).thenReturn(new DummyLocation());
+		when(mock.getType()).thenReturn(Location.class);
+
+		buf = new ReadBufferDataHandle(mock, 10, 2);
+		byteArrayLen10 = new byte[10];
+
+		// update offset on mock read
+		when(mock.read(any(byte[].class))).thenAnswer(inv -> {
+			innerOffset += inv.<byte[]> getArgument(0).length;
+			return null;
+		});
+
+		// update offset on mock seek
+		doAnswer(inv -> {
+			innerOffset = inv.getArgument(0);
+			return null;
+		}).when(mock).seek(anyLong());
+
+		// mock offset
+		when(mock.offset()).then(inv -> {
+			return innerOffset;
+		});
+	}
+
+	@Test
+	public void testBufferingSequence() throws IOException {
+
+		// set length of stubbed handle
+		when(mock.length()).thenReturn(30l);
+
+		// read the first byte
+		buf.read();
+		verify(mock, times(0)).seek(0);
+		// buffer should read a whole page
+		verify(mock).read(aryEq(byteArrayLen10));
+
+		buf.seek(0);
+		// ensure seek was not called again
+		verify(mock, times(0)).seek(0);
+
+		// read over the edge of the current page
+		buf.read(new byte[12]);
+		verify(mock, times(0)).seek(anyLong());
+		verify(mock, times(2)).read(aryEq(byteArrayLen10));
+
+		assertEquals(12, buf.offset());
+
+		// read the last page
+		buf.read(new byte[12]);
+		verify(mock, times(0)).seek(anyLong());
+		verify(mock, times(3)).read(aryEq(byteArrayLen10));
+
+		// first page should no longer be buffered, must be reread in
+		buf.seek(0);
+		buf.read();
+		verify(mock).seek(0);
+		verify(mock, times(4)).read(aryEq(byteArrayLen10));
+	}
+
+	/**
+	 * Tests that we do not buffer pages that are not needed and
+	 *
+	 * @throws IOException
+	 */
+	@Test
+	public void testSkipForward() throws IOException {
+
+		// set length of stubbed handle
+		when(mock.length()).thenReturn(40l);
+
+		// read the first byte
+		buf.read();
+		verify(mock, times(0)).seek(anyLong());
+		verify(mock).read(aryEq(byteArrayLen10));
+
+		// skip the second page
+		buf.seek(30l);
+		buf.read();
+
+		// read the third page
+		verify(mock).seek(30l);
+		verify(mock, times(2)).read(aryEq(byteArrayLen10));
+
+		// go back to already buffered page
+		buf.seek(0l);
+		buf.read();
+
+		verify(mock, times(1)).seek(anyLong());
+
+		// go back to third page
+		buf.seek(35);
+		buf.read();
+		verify(mock, times(1)).seek(anyLong());
+		verify(mock, times(2)).read(any());
+	}
+}