Void return types need to always be null value

Void type in Java cannot be instantiated, therefore if a type is declared as Void the fromJson should always set that value to null. If you want to have a generic return type that allows non-null and null results, use a type other than Void as the return type. Fixes #721
eclipse-lsp4j · May 9, 2023 · 79df5e2 · 79df5e2
1 parent 3d55fa0
commit 79df5e2
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Showing 4 changed files with 101 additions and 25 deletions.
diff --git a/...sonrpc.debug/src/test/java/org/eclipse/lsp4j/jsonrpc/debug/test/DebugIntegrationTest.java b/...sonrpc.debug/src/test/java/org/eclipse/lsp4j/jsonrpc/debug/test/DebugIntegrationTest.java
@@ -56,6 +56,12 @@ public static interface MyServer {
 		CompletableFuture<MyParam> askServer(MyParam param);
 	}
 
+
+	public static interface MyVoidServer {
+		@JsonRequest
+		CompletableFuture<Void> askServer(MyParam param);
+	}
+
 	public static interface MyClient {
 		@JsonRequest
 		CompletableFuture<MyParam> askClient(MyParam param);
@@ -99,6 +105,45 @@ public CompletableFuture<MyParam> askServer(MyParam param) {
 		Assert.assertEquals("BAR", barFuture.get(TIMEOUT, TimeUnit.MILLISECONDS).value);
 	}
 
+	@Test
+	public void testVoidResponse() throws Exception {
+		// create client side
+		PipedInputStream in = new PipedInputStream();
+		PipedOutputStream out = new PipedOutputStream();
+		PipedInputStream in2 = new PipedInputStream();
+		PipedOutputStream out2 = new PipedOutputStream();
+
+		in.connect(out2);
+		out.connect(in2);
+
+		MyClient client = new MyClient() {
+			@Override
+			public CompletableFuture<MyParam> askClient(MyParam param) {
+				throw new UnsupportedOperationException("Unused by this test");
+			}
+		};
+		Launcher<MyVoidServer> clientSideLauncher = DebugLauncher.createLauncher(client, MyVoidServer.class, in, out);
+
+		// create server side
+		MyServer server = new MyServer() {
+			@Override
+			public CompletableFuture<MyParam> askServer(MyParam param) {
+				return CompletableFuture.completedFuture(param);
+			}
+		};
+		Launcher<MyClient> serverSideLauncher = DebugLauncher.createLauncher(server, MyClient.class, in2, out2);
+
+		clientSideLauncher.startListening();
+		serverSideLauncher.startListening();
+
+		// We call a method that is declared as returning Void, but the other end returns a non-null value
+		// make sure that the json parsing discards that result
+		CompletableFuture<Void> fooFuture = clientSideLauncher.getRemoteProxy().askServer(new MyParam("FOO"));
+
+		Void void1 = fooFuture.get(TIMEOUT, TimeUnit.MILLISECONDS);
+		Assert.assertNull(void1);
+	}
+
 	@Test
 	public void testCancellation() throws Exception {
 		// create client side

diff --git a/.../src/test/java/org/eclipse/lsp4j/jsonrpc/debug/test/json/DebugMessageJsonHandlerTest.java b/.../src/test/java/org/eclipse/lsp4j/jsonrpc/debug/test/json/DebugMessageJsonHandlerTest.java
@@ -850,7 +850,7 @@ public void testParseSyntaxErrorRequest() {
 		}
 	}
 
-	private Object voidResponse(String body) {
+	private void voidResponse(String body) {
 		Map<String, JsonRpcMethod> supportedMethods = new LinkedHashMap<>();
 		supportedMethods.put("foo", JsonRpcMethod.request("foo", new TypeToken<Void>() {
 		}.getType(), new TypeToken<Void>() {
@@ -870,56 +870,42 @@ private Object voidResponse(String body) {
 				+ "\"success\":true"//
 				+ bodyField //
 				+ "}\n");
-		return ((ResponseMessage) message).getResult();
+		Object result = ((ResponseMessage) message).getResult();
+		Assert.assertNull(result);
 	}
 
 	@Test
 	public void testVoidResponse_noBody() {
-		Assert.assertNull(voidResponse(null));
+		voidResponse(null);
 	}
 
 	@Test
 	public void testVoidResponse_null() {
-		Assert.assertNull(voidResponse("null"));
-
+		voidResponse("null");
 	}
 
 	@Test
 	public void testVoidResponse_primitive() {
-		Object result = voidResponse("true");
-		JsonPrimitive jsonPrimitive = (JsonPrimitive) result;
-		Assert.assertTrue(jsonPrimitive.getAsBoolean());
+		voidResponse("true");
 	}
 
 	@Test
 	public void testVoidResponse_emptyArray() {
-		Object result = voidResponse("[]");
-		JsonArray jsonArray = (JsonArray) result;
-		Assert.assertTrue(jsonArray.isEmpty());
+		voidResponse("[]");
 	}
 
 	@Test
 	public void testVoidResponse_array() {
-		Object result = voidResponse("[1,2,3]");
-		JsonArray jsonArray = (JsonArray) result;
-		Assert.assertEquals(1, jsonArray.get(0).getAsInt());
-		Assert.assertEquals(2, jsonArray.get(1).getAsInt());
-		Assert.assertEquals(3, jsonArray.get(2).getAsInt());
+		voidResponse("[1,2,3]");
 	}
 
 	@Test
 	public void testVoidResponse_emptyObject() {
-		Object result = voidResponse("{}");
-		Assert.assertTrue(result instanceof JsonObject);
-		JsonObject jsonObject = (JsonObject) result;
-		Assert.assertTrue(jsonObject.entrySet().isEmpty());
+		voidResponse("{}");
 	}
 
 	@Test
 	public void testVoidResponse_object() {
-		Object result = voidResponse("{\"allThreadsContinued\":false}");
-		Assert.assertTrue(result instanceof JsonObject);
-		JsonObject jsonObject = (JsonObject) result;
-		Assert.assertFalse(jsonObject.getAsJsonPrimitive("allThreadsContinued").getAsBoolean());
+		voidResponse("{\"allThreadsContinued\":false}");
 	}
 }
diff --git a/...p4j.jsonrpc/src/main/java/org/eclipse/lsp4j/jsonrpc/json/adapters/MessageTypeAdapter.java b/...p4j.jsonrpc/src/main/java/org/eclipse/lsp4j/jsonrpc/json/adapters/MessageTypeAdapter.java
@@ -350,7 +350,7 @@ protected Object fromJson(JsonElement element, Type type) {
 			return null;
 		}
 		if (isNullOrVoidType(type)) {
-			return element;
+			return null;
 		}
 		Object value = gson.fromJson(element, type);
 		if (isNull(value)) {

diff --git a/org.eclipse.lsp4j.jsonrpc/src/test/java/org/eclipse/lsp4j/jsonrpc/test/IntegrationTest.java b/org.eclipse.lsp4j.jsonrpc/src/test/java/org/eclipse/lsp4j/jsonrpc/test/IntegrationTest.java
@@ -31,6 +31,7 @@
 import org.eclipse.lsp4j.jsonrpc.Launcher;
 import org.eclipse.lsp4j.jsonrpc.RemoteEndpoint;
 import org.eclipse.lsp4j.jsonrpc.ResponseErrorException;
+
 import org.eclipse.lsp4j.jsonrpc.json.StreamMessageProducer;
 import org.eclipse.lsp4j.jsonrpc.messages.Either;
 import org.eclipse.lsp4j.jsonrpc.services.GenericEndpoint;
@@ -88,6 +89,11 @@ public static interface MyServer {
 		@JsonRequest
 		CompletableFuture<MyParam> askServer(MyParam param);
 	}
+
+	public static interface MyVoidServer {
+		@JsonRequest
+		CompletableFuture<Void> askServer(MyParam param);
+	}
 
 	public static class MyServerImpl implements MyServer {
 		@Override
@@ -224,6 +230,45 @@ public void testEitherNull() throws Exception {
 				out.toString());
 	}
 
+	@Test
+	public void testVoidResponse() throws Exception {
+		// create client side
+		PipedInputStream in = new PipedInputStream();
+		PipedOutputStream out = new PipedOutputStream();
+		PipedInputStream in2 = new PipedInputStream();
+		PipedOutputStream out2 = new PipedOutputStream();
+
+		in.connect(out2);
+		out.connect(in2);
+
+		MyClient client = new MyClient() {
+			@Override
+			public CompletableFuture<MyParam> askClient(MyParam param) {
+				throw new UnsupportedOperationException("Unused by this test");
+			}
+		};
+		Launcher<MyVoidServer> clientSideLauncher = Launcher.createLauncher(client, MyVoidServer.class, in, out);
+
+		// create server side
+		MyServer server = new MyServer() {
+			@Override
+			public CompletableFuture<MyParam> askServer(MyParam param) {
+				return CompletableFuture.completedFuture(param);
+			}
+		};
+		Launcher<MyClient> serverSideLauncher = Launcher.createLauncher(server, MyClient.class, in2, out2);
+
+		clientSideLauncher.startListening();
+		serverSideLauncher.startListening();
+
+		// We call a method that is declared as returning Void, but the other end returns a non-null value
+		// make sure that the json parsing discards that result
+		CompletableFuture<Void> fooFuture = clientSideLauncher.getRemoteProxy().askServer(new MyParam("FOO"));
+
+		Void void1 = fooFuture.get(TIMEOUT, TimeUnit.MILLISECONDS);
+		Assert.assertNull(void1);
+	}
+
 
 	@Test
 	public void testCancellation() throws Exception {