Fix shm test failures on macOS

On macOS, the size of the allocated shared memory block might not
precisely match the request. But it needs to be at least as large as
the requested size. E.g.: sizes less than 16384 round up to 16384.

You might think it would be a good idea to make the size() method
of SharedMemory return the actually requested size, rather than the
weird rounded up size, but that's how it works on macOS on Python,
and we're trying to make the Java implementation match the Python
behavior as closely as possible, so... ¯\_(ツ)_/¯

src/test/java/org/apposed/appose/SharedMemoryTest.java

@@ -41,6 +41,7 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * Tests {@link SharedMemory}.
@@ -54,7 +55,7 @@ public void testShmCreate() throws IOException {
 		int size = 456;
 		try (SharedMemory shm = SharedMemory.create(null, size)) {
 			assertNotNull(shm.name());
-			assertEquals(size, shm.size());
+			assertTrue(shm.size() >= size);
 			assertNotNull(shm.pointer());
 
 			// Modify the memory contents.
@@ -74,8 +75,8 @@ public void testShmCreate() throws IOException {
 			String output = runPython(
 				"from multiprocessing.shared_memory import SharedMemory\n" +
 					"from sys import stdout\n" +
-					"shm = SharedMemory(name='" + shm.name() + "', size=" + shm.size() + ")\n" +
-					"matches = sum(1 for i in range(shm.size) if shm.buf[i] == (shm.size - i) % 256)\n" +
+					"shm = SharedMemory(name='" + shm.name() + "', size=" + size + ")\n" +
+					"matches = sum(1 for i in range(" + size + ") if shm.buf[i] == (" + size + " - i) % 256)\n" +
 					"stdout.write(f'{matches}\\n')\n" +
 					"stdout.flush()\n" +
 					"shm.unlink()\n" // HACK: to satisfy Python's overly aggressive resource tracker
@@ -112,7 +113,7 @@ public void testShmAttach() throws IOException {
 		assertNotNull(shmName);
 		assertFalse(shmName.isEmpty());
 		int shmSize = Integer.parseInt(shmInfo[1]);
-		assertEquals(345, shmSize);
+		assertTrue(shmSize >= 345);
 
 		// Attach to the shared memory and verify it matches expectations.
 		try (SharedMemory shm = SharedMemory.attach(shmName, shmSize)) {

src/test/java/org/apposed/appose/TypesTest.java

@@ -70,7 +70,7 @@ public class TypesTest {
 			"\"shm\":{" +
 				"\"appose_type\":\"shm\"," +
 				"\"name\":\"SHM_NAME\"," +
-				"\"size\":4000" +
+				"\"size\":SHM_SIZE" +
 			"}" +
 		"}" +
 	"}";
@@ -110,7 +110,9 @@ public void testEncode() {
 			data.put("ndArray", ndArray);
 			String json = Types.encode(data);
 			assertNotNull(json);
-			String expected = JSON.replaceAll("SHM_NAME", ndArray.shm().name());
+			String expected = JSON
+				.replaceAll("SHM_NAME", ndArray.shm().name())
+				.replaceAll("SHM_SIZE", "" + ndArray.shm().size());
 			assertEquals(expected, json);
 		}
 	}
@@ -119,11 +121,16 @@ public void testEncode() {
 	public void testDecode() {
 		Map<String, Object> data;
 		String shmName;
+		int shmSize;
 
 		// Create name shared memory segment and decode JSON block.
 		try (SharedMemory shm = SharedMemory.create(null, 4000)) {
 			shmName = shm.name();
-			data = Types.decode(JSON.replaceAll("SHM_NAME", shmName));
+			shmSize = shm.size();
+			String json = JSON
+				.replaceAll("SHM_NAME", shmName)
+				.replaceAll("SHM_SIZE", "" + shmSize);
+			data = Types.decode(json);
 		}
 
 		// Validate results.
@@ -158,7 +165,7 @@ public void testDecode() {
 			assertEquals(20, ndArray.shape().get(1));
 			assertEquals(25, ndArray.shape().get(2));
 			assertEquals(shmName, ndArray.shm().name());
-			assertEquals(4000, ndArray.shm().size());
+			assertEquals(shmSize, ndArray.shm().size());
 		}
 	}