Adapt timeseries tests to avoid mockito on ByteBuffer failing on java19

We get an exception:
    org.mockito.exceptions.base.MockitoException:
    Mockito cannot mock this class: class java.nio.ByteBuffer.

Try to use java.nio APIs to use no resources (sparse, private), not sure
how this works on all platforms..

Signed-off-by: HARPER Jon <jon.harper87@gmail.com>

time-series/time-series-api/src/test/java/com/powsybl/timeseries/AbstractBigBufferTest.java

@@ -0,0 +1,58 @@
+/**
+ * Copyright (c) 2023, RTE (http://www.rte-france.com)
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+package com.powsybl.timeseries;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.AfterEach;
+
+import java.nio.file.StandardOpenOption;
+import java.nio.channels.FileChannel;
+import java.nio.ByteBuffer;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import java.util.List;
+import java.util.ArrayList;
+
+/**
+ * @author Jon Harper <jon.harper at rte-france.com>
+ */
+abstract class AbstractBigBufferTest {
+
+    private Path tempdir;
+    protected List<FileChannel> channels;
+
+    protected ByteBuffer testAllocator(int capacity) {
+        try {
+            FileChannel channel = FileChannel.open(
+                tempdir.resolve(Integer.toString(channels.size())),
+                StandardOpenOption.READ, StandardOpenOption.WRITE,
+                StandardOpenOption.CREATE_NEW, StandardOpenOption.SPARSE,
+                StandardOpenOption.DELETE_ON_CLOSE);
+            channels.add(channel);
+            ByteBuffer bytebuffer = channel.map(FileChannel.MapMode.PRIVATE, 0, capacity);
+            return bytebuffer;
+        } catch (Exception e) {
+            throw new RuntimeException("error in allocator test", e);
+        }
+    }
+
+    @BeforeEach
+    void before() throws Exception {
+        tempdir = Files.createTempDirectory("powsybltimeseriestest");
+        channels = new ArrayList<>();
+    }
+
+    @AfterEach
+    void after() throws Exception {
+        for (FileChannel channel : channels) {
+            channel.close();
+        }
+        Files.delete(tempdir);
+    }
+
+}

time-series/time-series-api/src/test/java/com/powsybl/timeseries/BigDoubleBufferTest.java

@@ -6,52 +6,19 @@
  */
 package com.powsybl.timeseries;
 
-import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
-import org.mockito.Mockito;
-
-import java.nio.ByteBuffer;
-import java.nio.DoubleBuffer;
-import java.util.HashMap;
-import java.util.Map;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.mockito.Mockito.*;
 
 /**
  * @author Jon Harper <jon.harper at rte-france.com>
  */
-class BigDoubleBufferTest {
+class BigDoubleBufferTest extends AbstractBigBufferTest {
 
     private static final int BUFFER_SIZE_DOUBLES = 1 << 27;
 
-    private int allocatorCount;
-
-    private ByteBuffer testDoubleAllocator(int capacity) {
-        allocatorCount++;
-        ByteBuffer mockbyte = Mockito.mock(ByteBuffer.class);
-        DoubleBuffer mockdouble = Mockito.mock(DoubleBuffer.class);
-        when(mockbyte.asDoubleBuffer()).thenReturn(mockdouble);
-        Map<Integer, Double> map = new HashMap<>();
-        when(mockdouble.put(anyInt(), anyDouble())).thenAnswer(invocation -> {
-            Object[] args = invocation.getArguments();
-            DoubleBuffer mock = (DoubleBuffer) invocation.getMock();
-            map.put((int) args[0], (double) args[1]);
-            return mock;
-        });
-        when(mockdouble.get(anyInt())).thenAnswer(invocation -> {
-            return map.get(invocation.getArguments()[0]);
-        });
-        return mockbyte;
-    }
-
-    @BeforeEach
-    void before() {
-        allocatorCount = 0;
-    }
-
     private void bufferTester(long size) {
-        BigDoubleBuffer buffer = new BigDoubleBuffer(this::testDoubleAllocator, size);
+        BigDoubleBuffer buffer = new BigDoubleBuffer(this::testAllocator, size);
         //Simple writes at the begining
         for (int i = 0; i < 10; i++) {
             buffer.put(i, i);
@@ -83,36 +50,36 @@ private void bufferTester(long size) {
     @Test
     void testSimple() {
         bufferTester(10);
-        assertEquals(1, allocatorCount);
+        assertEquals(1, channels.size());
     }
 
     @Test
     void testMultipleBuffers() {
         bufferTester(200000000);
-        assertEquals(2, allocatorCount);
+        assertEquals(2, channels.size());
     }
 
     @Test
     void testHuge() {
         bufferTester(10000000000L);
-        assertEquals(75, allocatorCount);
+        assertEquals(75, channels.size());
     }
 
     @Test
     void testSizeBufferMinus1() {
         bufferTester(BUFFER_SIZE_DOUBLES - 1);
-        assertEquals(1, allocatorCount);
+        assertEquals(1, channels.size());
     }
 
     @Test
     void testSizeBufferExact() {
         bufferTester(BUFFER_SIZE_DOUBLES);
-        assertEquals(1, allocatorCount);
+        assertEquals(1, channels.size());
     }
 
     @Test
     void testSizeBufferPlus1() {
         bufferTester(BUFFER_SIZE_DOUBLES + 1);
-        assertEquals(2, allocatorCount);
+        assertEquals(2, channels.size());
     }
 }

time-series/time-series-api/src/test/java/com/powsybl/timeseries/BigStringBufferTest.java

@@ -6,53 +6,19 @@
  */
 package com.powsybl.timeseries;
 
-import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
-import org.mockito.Mockito;
-
-import java.nio.ByteBuffer;
-import java.nio.IntBuffer;
-import java.util.HashMap;
-import java.util.Map;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.mockito.Mockito.anyInt;
-import static org.mockito.Mockito.when;
 
 /**
  * @author Jon Harper <jon.harper at rte-france.com>
  */
-class BigStringBufferTest {
+class BigStringBufferTest extends AbstractBigBufferTest {
 
     private static final int BUFFER_SIZE_INTS = 1 << 28;
 
-    private int allocatorCount;
-
-    private ByteBuffer testStringAllocator(int capacity) {
-        allocatorCount++;
-        ByteBuffer mockbyte = Mockito.mock(ByteBuffer.class);
-        IntBuffer mockint = Mockito.mock(IntBuffer.class);
-        when(mockbyte.asIntBuffer()).thenReturn(mockint);
-        Map<Integer, Integer> map = new HashMap<>();
-        when(mockint.put(anyInt(), anyInt())).thenAnswer(invocation -> {
-            Object[] args = invocation.getArguments();
-            IntBuffer mock = (IntBuffer) invocation.getMock();
-            map.put((int) args[0], (int) args[1]);
-            return mock;
-        });
-        when(mockint.get(anyInt())).thenAnswer(invocation -> {
-            return map.get(invocation.getArguments()[0]);
-        });
-        return mockbyte;
-    }
-
-    @BeforeEach
-    void before() {
-        allocatorCount = 0;
-    }
-
     private void bufferTester(long size) {
-        BigStringBuffer buffer = new BigStringBuffer(this::testStringAllocator, size);
+        BigStringBuffer buffer = new BigStringBuffer(this::testAllocator, size);
         //Simple writes at the begining
         for (int i = 0; i < 10; i++) {
             buffer.putString(i, Integer.toString(i));
@@ -84,36 +50,36 @@ private void bufferTester(long size) {
     @Test
     void testSimple() {
         bufferTester(10);
-        assertEquals(1, allocatorCount);
+        assertEquals(1, channels.size());
     }
 
     @Test
     void testMultipleBuffers() {
         bufferTester(400000000);
-        assertEquals(2, allocatorCount);
+        assertEquals(2, channels.size());
     }
 
     @Test
     void testHuge() {
         bufferTester(10000000000L);
-        assertEquals(38, allocatorCount);
+        assertEquals(38, channels.size());
     }
 
     @Test
     void testSizeBufferMinus1() {
         bufferTester(BUFFER_SIZE_INTS - 1);
-        assertEquals(1, allocatorCount);
+        assertEquals(1, channels.size());
     }
 
     @Test
     void testSizeBufferExact() {
         bufferTester(BUFFER_SIZE_INTS);
-        assertEquals(1, allocatorCount);
+        assertEquals(1, channels.size());
     }
 
     @Test
     void testSizeBufferPlus1() {
         bufferTester(BUFFER_SIZE_INTS + 1);
-        assertEquals(2, allocatorCount);
+        assertEquals(2, channels.size());
     }
 }