[mlir-lsp] Add transport unit tests (#89855)

Add unit tests for some aspects of the JSON transport and message
handler. These will be expanded in future patches as behavior is
modified.

mlir/unittests/CMakeLists.txt

@@ -20,6 +20,7 @@ add_subdirectory(Support)
 add_subdirectory(Rewrite)
 add_subdirectory(TableGen)
 add_subdirectory(Target)
+add_subdirectory(Tools)
 add_subdirectory(Transforms)
 
 if(MLIR_ENABLE_EXECUTION_ENGINE)

mlir/unittests/Tools/CMakeLists.txt

@@ -0,0 +1 @@
+add_subdirectory(lsp-server-support)

mlir/unittests/Tools/lsp-server-support/CMakeLists.txt

@@ -0,0 +1,6 @@
+add_mlir_unittest(MLIRLspServerSupportTests
+  Transport.cpp
+)
+target_link_libraries(MLIRLspServerSupportTests
+  PRIVATE
+  MLIRLspServerSupportLib)

mlir/unittests/Tools/lsp-server-support/Transport.cpp

@@ -0,0 +1,65 @@
+//===- Transport.cpp - LSP JSON transport unit tests ----------------------===//
+//
+// 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 "mlir/Tools/lsp-server-support/Transport.h"
+#include "llvm/ADT/ScopeExit.h"
+#include "llvm/Support/FileSystem.h"
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+
+using namespace mlir;
+using namespace mlir::lsp;
+using namespace testing;
+
+namespace {
+
+TEST(TransportTest, SendReply) {
+  std::string out;
+  llvm::raw_string_ostream os(out);
+  JSONTransport transport(nullptr, os);
+  MessageHandler handler(transport);
+
+  transport.reply(1989, nullptr);
+  EXPECT_THAT(out, HasSubstr("\"id\":1989"));
+  EXPECT_THAT(out, HasSubstr("\"result\":null"));
+}
+
+TEST(TransportTest, MethodNotFound) {
+  auto tempOr = llvm::sys::fs::TempFile::create("lsp-unittest-%%%%%%.json");
+  ASSERT_TRUE((bool)tempOr);
+  auto discardTemp =
+      llvm::make_scope_exit([&]() { ASSERT_FALSE((bool)tempOr->discard()); });
+
+  {
+    std::error_code ec;
+    llvm::raw_fd_ostream os(tempOr->TmpName, ec);
+    ASSERT_FALSE(ec);
+    os << "{\"jsonrpc\":\"2.0\",\"id\":29,\"method\":\"ack\"}\n";
+    os.close();
+  }
+
+  std::string out;
+  llvm::raw_string_ostream os(out);
+  std::FILE *in = std::fopen(tempOr->TmpName.c_str(), "r");
+  auto closeIn = llvm::make_scope_exit([&]() { std::fclose(in); });
+
+  JSONTransport transport(in, os, JSONStreamStyle::Delimited);
+  MessageHandler handler(transport);
+
+  bool gotEOF = false;
+  llvm::Error err = llvm::handleErrors(
+      transport.run(handler), [&](const llvm::ECError &ecErr) {
+        gotEOF = ecErr.convertToErrorCode() == std::errc::io_error;
+      });
+  llvm::consumeError(std::move(err));
+  EXPECT_TRUE(gotEOF);
+  EXPECT_THAT(out, HasSubstr("\"id\":29"));
+  EXPECT_THAT(out, HasSubstr("\"error\""));
+  EXPECT_THAT(out, HasSubstr("\"message\":\"method not found: ack\""));
+}
+} // namespace