[clangd] Set up machinery for gtests of ClangdLSPServer.

[sammccall]

Summary

This is going to be needed to test e.g. diagnostics regeneration on
didSave where files changed on disk. Coordinating such changes is too
hard in lit tests.

[sammccall]

It seems fairly likely that this is a big complicated thing we end up using for 1 or 2 tests that are too hard to test with lit but can't be tested at a lower level than ClangdLSPServer.
Suggestions on how to make it more lightweight would be welcome!

[kadircet]

LGTM, mostly nits.

Unfortunately I don't see any way to make it simpler :/

clang-tools-extra/clangd/unittests/ClangdLSPServerTests.cpp

105

nit: move this to top of the file

clang-tools-extra/clangd/unittests/LSPClient.cpp

66

put methods before fields

69

i think logging errors here could help with debugging.

72

nit: static_cast

100

this check should happen before accessing Actions.front

107

put public before private

158

ah, the !Action check for stop now makes sense :D maybe get rid of the Stop flag inside transportimpl and say an empty action terminates the loop or make this invoke a T->stop(); which sets the flag

198

URI is not an optional field, so shouldn't !U -> ADD_FAILURE() ?

200

again diagnostics is not optional

clang-tools-extra/clangd/unittests/LSPClient.h

45

nit: put it before members, also some comments about "multiple call is failure" might be nice

[sammccall]

Address review comments

clang-tools-extra/clangd/unittests/LSPClient.cpp

66

Done - I don't care much, but curious where this guideline comes from?
My impression is LLVM puts members at the very top of the class or at the very bottom (like google-style).
DependentSizedArrayType is a random example.

69

Errors don't have bodies, the mesasge is already logged by clangdlspserver. Added a comment.

[kadircet]

clang-tools-extra/clangd/unittests/LSPClient.cpp

66

i believe most of the code in LLVM puts the members at the top of the class. but my impression was in clangd code we tend to put members at the very bottom, hence i suggested that. personally i actually find having members at the top more useful.

clang-tools-extra/clangd/unittests/CMakeLists.txt

 add_custom_target(ClangdUnitTests)
 add_unittest(ClangdUnitTests ClangdTests
   Annotations.cpp
   ASTTests.cpp
   BackgroundIndexTests.cpp
   CancellationTests.cpp
   CanonicalIncludesTests.cpp
   ClangdTests.cpp
+  ClangdLSPServerTests.cpp
   CodeCompleteTests.cpp
   CodeCompletionStringsTests.cpp
   CollectMacrosTests.cpp
   CompileCommandsTests.cpp
   ContextTests.cpp
   DexTests.cpp
   DiagnosticsTests.cpp
   DraftStoreTests.cpp
add_unittest(ClangdUnitTests ClangdTests
   FuzzyMatchTests.cpp
   GlobalCompilationDatabaseTests.cpp
   HeadersTests.cpp
   HeaderSourceSwitchTests.cpp
   HoverTests.cpp
   IndexActionTests.cpp
   IndexTests.cpp
   JSONTransportTests.cpp
+  LSPClient.cpp
   ParsedASTTests.cpp
   PathMappingTests.cpp
   PrintASTTests.cpp
   QualityTests.cpp
   RenameTests.cpp
   RIFFTests.cpp
   SelectionTests.cpp
   SemanticHighlightingTests.cpp

clang-tools-extra/clangd/unittests/ClangdLSPServerTests.cpp

+//===-- ClangdLSPServerTests.cpp ------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "Annotations.h"
+#include "ClangdLSPServer.h"
+#include "CodeComplete.h"
+#include "LSPClient.h"
+#include "Logger.h"
+#include "Protocol.h"
+#include "TestFS.h"
+#include "refactor/Rename.h"
+#include "llvm/Support/JSON.h"
+#include "llvm/Testing/Support/SupportHelpers.h"
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+
+namespace clang {
+namespace clangd {
+namespace {
+
+MATCHER_P(DiagMessage, M, "") {
+  if (const auto *O = arg.getAsObject()) {
+    if (const auto Msg = O->getString("message"))
+      return *Msg == M;
+  }
+  return false;
+}
+
+class LSPTest : public ::testing::Test, private clangd::Logger {
+protected:
+  LSPTest() : LogSession(*this) {}
+
+  LSPClient &start() {
+    EXPECT_FALSE(Server.hasValue()) << "Already initialized";
+    Server.emplace(Client.transport(), FS, CCOpts, RenameOpts,
+                   /*CompileCommandsDir=*/llvm::None, /*UseDirBasedCDB=*/false,
+                   /*ForcedOffsetEncoding=*/llvm::None, Opts);
+    ServerThread.emplace([&] { EXPECT_TRUE(Server->run()); });
+    Client.call("initialize", llvm::json::Object{});
+    return Client;
+  }
+
+  void stop() {
+    assert(Server);
+    Client.call("shutdown", nullptr);
+    Client.notify("exit", nullptr);
+    Client.stop();
+    ServerThread->join();
+    Server.reset();
+    ServerThread.reset();
+  }
+
+  ~LSPTest() {
+    if (Server)
+      stop();
+  }
+
+  MockFSProvider FS;
+  CodeCompleteOptions CCOpts;
+  RenameOptions RenameOpts;
+  ClangdServer::Options Opts = ClangdServer::optsForTest();
+
+private:
+  // Color logs so we can distinguish them from test output.
+  void log(Level L, const llvm::formatv_object_base &Message) override {
+    raw_ostream::Colors Color;
+    switch (L) {
+    case Level::Verbose:
+      Color = raw_ostream::BLUE;
+      break;
+    case Level::Error:
+      Color = raw_ostream::RED;
+      break;
+    default:
+      Color = raw_ostream::YELLOW;
+      break;
+    }
+    std::lock_guard<std::mutex> Lock(LogMu);
+    (llvm::outs().changeColor(Color) << Message << "\n").resetColor();
+  }
+  std::mutex LogMu;
+
+  LoggingSession LogSession;
+  llvm::Optional<ClangdLSPServer> Server;
+  llvm::Optional<std::thread> ServerThread;
+  LSPClient Client;
+};
+
+TEST_F(LSPTest, GoToDefinition) {
+  Annotations Code(R"cpp(
+    int [[fib]](int n) {
+      return n >= 2 ? ^fib(n - 1) + fib(n - 2) : 1;
+    }
+  )cpp");
+  auto &Client = start();
+  Client.didOpen("foo.cpp", Code.code());
+  auto &Def = Client.call("textDocument/definition",
+                          llvm::json::Object{
+                              {"textDocument", Client.documentID("foo.cpp")},
+                              {"position", Code.point()},
+                          });
+  llvm::json::Value Want = llvm::json::Array{llvm::json::Object{
+      {"uri", Client.uri("foo.cpp")}, {"range", Code.range()}}};
+  EXPECT_EQ(Def.takeValue(), Want);
+}
+
+TEST_F(LSPTest, Diagnostics) {
+  auto &Client = start();
+  Client.didOpen("foo.cpp", "void main(int, char**);");
+  EXPECT_THAT(Client.diagnostics("foo.cpp"),
+              llvm::ValueIs(testing::ElementsAre(
+                  DiagMessage("'main' must return 'int' (fix available)"))));
+
+  Client.didChange("foo.cpp", "int x = \"42\";");
+  EXPECT_THAT(Client.diagnostics("foo.cpp"),
+              llvm::ValueIs(testing::ElementsAre(
+                  DiagMessage("Cannot initialize a variable of type 'int' with "
+                              "an lvalue of type 'const char [3]'"))));
+
+  Client.didClose("foo.cpp");
+  EXPECT_THAT(Client.diagnostics("foo.cpp"), llvm::ValueIs(testing::IsEmpty()));
+}
+
+} // namespace
+} // namespace clangd
+} // namespace clang

clang-tools-extra/clangd/unittests/LSPClient.h

+//===-- LSPClient.h - Helper for ClangdLSPServer tests ----------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <condition_variable>
+#include <deque>
+#include <llvm/ADT/Optional.h>
+#include <llvm/Support/Error.h>
+#include <llvm/Support/JSON.h>
+#include <mutex>
+
+namespace clang {
+namespace clangd {
+class Transport;
+
+// A client library for talking to ClangdLSPServer in tests.
+// Manages serialization of messages, pairing requests/repsonses, and implements
+// the Transport abstraction.
+class LSPClient {
+  class TransportImpl;
+  std::unique_ptr<TransportImpl> T;
+
+public:
+  // Represents the result of an LSP call: a promise for a result or error.
+  class CallResult {
+  public:
+    ~CallResult();
+    // Blocks up to 10 seconds for the result to be ready.
+    // Records a test failure if there was no reply.
+    llvm::Expected<llvm::json::Value> take();
+    // Like take(), but records a test failure if the result was an error.
+    llvm::json::Value takeValue();
+
+  private:
+    // Should be called once to provide the value.
+    void set(llvm::Expected<llvm::json::Value> V);
+
+    llvm::Optional<llvm::Expected<llvm::json::Value>> Value;
+    std::mutex Mu;
+    std::condition_variable CV;
+
+    friend TransportImpl; // Calls set().
+  };
+
+  LSPClient();
+  ~LSPClient();
+  LSPClient(LSPClient &&) = delete;
+  LSPClient &operator=(LSPClient &&) = delete;
+
+  // Enqueue an LSP method call, returns a promise for the reply. Threadsafe.
+  CallResult &call(llvm::StringRef Method, llvm::json::Value Params);
+  // Enqueue an LSP notification. Threadsafe.
+  void notify(llvm::StringRef Method, llvm::json::Value Params);
+  // Returns matching notifications since the last call to takeNotifications.
+  std::vector<llvm::json::Value> takeNotifications(llvm::StringRef Method);
+  // The transport is shut down after all pending messages are sent.
+  void stop();
+
+  // Shorthand for common LSP methods. Relative paths are passed to testPath().
+  static llvm::json::Value uri(llvm::StringRef Path);
+  static llvm::json::Value documentID(llvm::StringRef Path);
+  void didOpen(llvm::StringRef Path, llvm::StringRef Content);
+  void didChange(llvm::StringRef Path, llvm::StringRef Content);
+  void didClose(llvm::StringRef Path);
+  // Blocks until the server is idle (using the 'sync' protocol extension).
+  void sync();
+  // sync()s to ensure pending diagnostics arrive, and returns the newest set.
+  llvm::Optional<std::vector<llvm::json::Value>>
+  diagnostics(llvm::StringRef Path);
+
+  // Get the transport used to connect this client to a ClangdLSPServer.
+  Transport &transport();
+
+private:
+};
+
+} // namespace clangd
+} // namespace clang

clang-tools-extra/clangd/unittests/LSPClient.cpp

+#include "LSPClient.h"
+#include "gtest/gtest.h"
+#include <condition_variable>
+
+#include "Protocol.h"
+#include "TestFS.h"
+#include "Threading.h"
+#include "Transport.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/raw_ostream.h"
+#include <queue>
+
+namespace clang {
+namespace clangd {
+
+llvm::Expected<llvm::json::Value> clang::clangd::LSPClient::CallResult::take() {
+  std::unique_lock<std::mutex> Lock(Mu);
+  if (!clangd::wait(Lock, CV, timeoutSeconds(10),
+                    [this] { return Value.hasValue(); })) {
+    ADD_FAILURE() << "No result from call after 10 seconds!";
+    return llvm::json::Value(nullptr);
+  }
+  return std::move(*Value);
+}
+
+llvm::json::Value LSPClient::CallResult::takeValue() {
+  auto ExpValue = take();
+  if (!ExpValue) {
+    ADD_FAILURE() << "takeValue(): " << llvm::toString(ExpValue.takeError());
+    return llvm::json::Value(nullptr);
+  }
+  return std::move(*ExpValue);
+}
+
+void LSPClient::CallResult::set(llvm::Expected<llvm::json::Value> V) {
+  std::lock_guard<std::mutex> Lock(Mu);
+  if (Value) {
+    ADD_FAILURE() << "Multiple replies";
+    llvm::consumeError(V.takeError());
+    return;
+  }
+  Value = std::move(V);
+  CV.notify_all();
+}
+
+LSPClient::CallResult::~CallResult() {
+  if (Value && !*Value) {
+    ADD_FAILURE() << llvm::toString(Value->takeError());
+  }
+}
+
+static void logBody(llvm::StringRef Method, llvm::json::Value V, bool Send) {
+  // We invert <<< and >>> as the combined log is from the server's viewpoint.
+  vlog("{0} {1}: {2:2}", Send ? "<<<" : ">>>", Method, V);
+}
+
+class LSPClient::TransportImpl : public Transport {
+public:
+  std::pair<llvm::json::Value, CallResult *> addCallSlot() {
+    std::lock_guard<std::mutex> Lock(Mu);
+    unsigned ID = CallResults.size();
+    CallResults.emplace_back();
+    return {ID, &CallResults.back()};
+  }
+
+  // A null action causes the transport to shut down.
+  void enqueue(std::function<void(MessageHandler &)> Action) {
+    std::lock_guard<std::mutex> Lock(Mu);
+    Actions.push(std::move(Action));
+    CV.notify_all();
+  }
+
+  std::vector<llvm::json::Value> takeNotifications(llvm::StringRef Method) {
+    std::vector<llvm::json::Value> Result;
+    {
+      std::lock_guard<std::mutex> Lock(Mu);
+      std::swap(Result, Notifications[Method]);
+    }
+    return Result;
+  }
+
+private:
+  void reply(llvm::json::Value ID,
+             llvm::Expected<llvm::json::Value> V) override {
+    if (V) // Nothing additional to log for error.
+      logBody("reply", *V, /*Send=*/false);
+    std::lock_guard<std::mutex> Lock(Mu);
+    if (auto I = ID.getAsInteger()) {
+      if (*I >= 0 && *I < static_cast<int64_t>(CallResults.size())) {
+        CallResults[*I].set(std::move(V));
+        return;
+      }
+    }
+    ADD_FAILURE() << "Invalid reply to ID " << ID;
+    llvm::consumeError(std::move(V).takeError());
+  }
+
+  void notify(llvm::StringRef Method, llvm::json::Value V) override {
+    logBody(Method, V, /*Send=*/false);
+    std::lock_guard<std::mutex> Lock(Mu);
+    Notifications[Method].push_back(std::move(V));
+  }
+
+  void call(llvm::StringRef Method, llvm::json::Value Params,
+            llvm::json::Value ID) override {
+    logBody(Method, Params, /*Send=*/false);
+    ADD_FAILURE() << "Unexpected server->client call " << Method;
+  }
+
+  llvm::Error loop(MessageHandler &H) override {
+    std::unique_lock<std::mutex> Lock(Mu);
+    while (true) {
+      CV.wait(Lock, [&] { return !Actions.empty(); });
+      if (!Actions.front()) // Stop!
+        return llvm::Error::success();
+      auto Action = std::move(Actions.front());
+      Actions.pop();
+      Lock.unlock();
+      Action(H);
+      Lock.lock();
+    }
+  }
+
+  std::mutex Mu;
+  std::deque<CallResult> CallResults;
+  std::queue<std::function<void(Transport::MessageHandler &)>> Actions;
+  std::condition_variable CV;
+  llvm::StringMap<std::vector<llvm::json::Value>> Notifications;
+};
+
+LSPClient::LSPClient() : T(std::make_unique<TransportImpl>()) {}
+LSPClient::~LSPClient() = default;
+
+LSPClient::CallResult &LSPClient::call(llvm::StringRef Method,
+                                       llvm::json::Value Params) {
+  auto Slot = T->addCallSlot();
+  T->enqueue([ID(Slot.first), Method(Method.str()),
+              Params(std::move(Params))](Transport::MessageHandler &H) {
+    logBody(Method, Params, /*Send=*/true);
+    H.onCall(Method, std::move(Params), ID);
+  });
+  return *Slot.second;
+}
+
+void LSPClient::notify(llvm::StringRef Method, llvm::json::Value Params) {
+  T->enqueue([Method(Method.str()),
+              Params(std::move(Params))](Transport::MessageHandler &H) {
+    logBody(Method, Params, /*Send=*/true);
+    H.onNotify(Method, std::move(Params));
+  });
+}
+
+std::vector<llvm::json::Value>
+LSPClient::takeNotifications(llvm::StringRef Method) {
+  return T->takeNotifications(Method);
+}
+
+void LSPClient::stop() { T->enqueue(nullptr); }
+
+Transport &LSPClient::transport() { return *T; }
+
+using Obj = llvm::json::Object;
+
+llvm::json::Value LSPClient::uri(llvm::StringRef Path) {
+  std::string Storage;
+  if (!llvm::sys::path::is_absolute(Path))
+    Path = Storage = testPath(Path);
+  return toJSON(URIForFile::canonicalize(Path, Path));
+}
+llvm::json::Value LSPClient::documentID(llvm::StringRef Path) {
+  return Obj{{"uri", uri(Path)}};
+}
+
+void LSPClient::didOpen(llvm::StringRef Path, llvm::StringRef Content) {
+  notify(
+      "textDocument/didOpen",
+      Obj{{"textDocument",
+           Obj{{"uri", uri(Path)}, {"text", Content}, {"languageId", "cpp"}}}});
+}
+void LSPClient::didChange(llvm::StringRef Path, llvm::StringRef Content) {
+  notify("textDocument/didChange",
+         Obj{{"textDocument", documentID(Path)},
+             {"contentChanges", llvm::json::Array{Obj{{"text", Content}}}}});
+}
+void LSPClient::didClose(llvm::StringRef Path) {
+  notify("textDocument/didClose", Obj{{"textDocument", documentID(Path)}});
+}
+
+void LSPClient::sync() { call("sync", nullptr).takeValue(); }
+
+llvm::Optional<std::vector<llvm::json::Value>>
+LSPClient::diagnostics(llvm::StringRef Path) {
+  sync();
+  auto Notifications = takeNotifications("textDocument/publishDiagnostics");
+  for (const auto &Notification : llvm::reverse(Notifications)) {
+    if (const auto *PubDiagsParams = Notification.getAsObject()) {
+      auto U = PubDiagsParams->getString("uri");
+      auto *D = PubDiagsParams->getArray("diagnostics");
+      if (!U || !D) {
+        ADD_FAILURE() << "Bad PublishDiagnosticsParams: " << PubDiagsParams;
+        continue;
+      }
+      if (*U == uri(Path))
+        return std::vector<llvm::json::Value>(D->begin(), D->end());
+    }
+  }
+  return {};
+}
+
+} // namespace clangd
+} // namespace clang