[lldb-dap] Setup DAP for unit testing. (#139937)

This is a very simple case that currently only validates we can create a
DAP instance and send a message over the transport layer. More in-depth
tests will require additional helpers and possibly refactors of DAP to
make it more testable, however this is some ground work to have basic
support for unit tests.

---------

Co-authored-by: Jonas Devlieghere <jonas@devlieghere.com>

7 files changed, 207 insertions, 16 deletions

diff --git a/lldb/tools/lldb-dap/DAP.h b/lldb/tools/lldb-dap/DAP.h
index 9065995f5d72..c1a1130b1e59 100644
--- a/lldb/tools/lldb-dap/DAP.h
+++ b/lldb/tools/lldb-dap/DAP.h
@@ -226,7 +226,8 @@ struct DAP {
   /// \param[in] default_repl_mode
   ///     Default repl mode behavior, as configured by the binary.
   /// \param[in] pre_init_commands
-  ///     LLDB commands to execute as soon as the debugger instance is allocaed.
+  ///     LLDB commands to execute as soon as the debugger instance is
+  ///     allocated.
   /// \param[in] transport
   ///     Transport for this debug session.
   DAP(Log *log, const ReplMode default_repl_mode,
diff --git a/lldb/unittests/DAP/CMakeLists.txt b/lldb/unittests/DAP/CMakeLists.txt
index 110733e93b19..af7d11e2e95e 100644
--- a/lldb/unittests/DAP/CMakeLists.txt
+++ b/lldb/unittests/DAP/CMakeLists.txt
@@ -1,8 +1,11 @@
 add_lldb_unittest(DAPTests
+  DAPTest.cpp
+  Handler/DisconnectTest.cpp
   JSONUtilsTest.cpp
   LLDBUtilsTest.cpp
-  TransportTest.cpp
   ProtocolTypesTest.cpp
+  TestBase.cpp
+  TransportTest.cpp
 
   LINK_LIBS
     lldbDAP
diff --git a/lldb/unittests/DAP/DAPTest.cpp b/lldb/unittests/DAP/DAPTest.cpp
new file mode 100644
index 000000000000..5fb6bf7e564a
--- /dev/null
+++ b/lldb/unittests/DAP/DAPTest.cpp
@@ -0,0 +1,38 @@
+//===-- DAPTest.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 "DAP.h"
+#include "Protocol/ProtocolBase.h"
+#include "TestBase.h"
+#include "Transport.h"
+#include "llvm/Testing/Support/Error.h"
+#include "gtest/gtest.h"
+#include <chrono>
+#include <memory>
+#include <optional>
+
+using namespace llvm;
+using namespace lldb;
+using namespace lldb_dap;
+using namespace lldb_dap_tests;
+using namespace lldb_dap::protocol;
+
+class DAPTest : public TransportBase {};
+
+TEST_F(DAPTest, SendProtocolMessages) {
+  DAP dap{
+      /*log=*/nullptr,
+      /*default_repl_mode=*/ReplMode::Auto,
+      /*pre_init_commands=*/{},
+      /*transport=*/*to_dap,
+  };
+  dap.Send(Event{/*event=*/"my-event", /*body=*/std::nullopt});
+  ASSERT_THAT_EXPECTED(from_dap->Read(std::chrono::milliseconds(1)),
+                       HasValue(testing::VariantWith<Event>(testing::FieldsAre(
+                           /*event=*/"my-event", /*body=*/std::nullopt))));
+}
diff --git a/lldb/unittests/DAP/Handler/DisconnectTest.cpp b/lldb/unittests/DAP/Handler/DisconnectTest.cpp
new file mode 100644
index 000000000000..6f3470239e97
--- /dev/null
+++ b/lldb/unittests/DAP/Handler/DisconnectTest.cpp
@@ -0,0 +1,35 @@
+//===-- DisconnectTest.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 "DAP.h"
+#include "Handler/RequestHandler.h"
+#include "Protocol/ProtocolBase.h"
+#include "TestBase.h"
+#include "llvm/Testing/Support/Error.h"
+#include "gtest/gtest.h"
+#include <memory>
+#include <optional>
+
+using namespace llvm;
+using namespace lldb;
+using namespace lldb_dap;
+using namespace lldb_dap_tests;
+using namespace lldb_dap::protocol;
+
+class DisconnectRequestHandlerTest : public DAPTestBase {};
+
+TEST_F(DisconnectRequestHandlerTest, DisconnectingTriggersTerminated) {
+  DisconnectRequestHandler handler(*dap);
+  EXPECT_FALSE(dap->disconnecting);
+  ASSERT_THAT_ERROR(handler.Run(std::nullopt), Succeeded());
+  EXPECT_TRUE(dap->disconnecting);
+  std::vector<Message> messages = DrainOutput();
+  EXPECT_THAT(messages,
+              testing::Contains(testing::VariantWith<Event>(testing::FieldsAre(
+                  /*event=*/"terminated", /*body=*/std::nullopt))));
+}
diff --git a/lldb/unittests/DAP/TestBase.cpp b/lldb/unittests/DAP/TestBase.cpp
new file mode 100644
index 000000000000..eb146cb2fa9f
--- /dev/null
+++ b/lldb/unittests/DAP/TestBase.cpp
@@ -0,0 +1,70 @@
+//===-- TestBase.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 "TestBase.h"
+#include "Protocol/ProtocolBase.h"
+#include "lldb/Host/File.h"
+#include "lldb/Host/Pipe.h"
+#include "llvm/Testing/Support/Error.h"
+
+using namespace llvm;
+using namespace lldb;
+using namespace lldb_dap;
+using namespace lldb_dap::protocol;
+using namespace lldb_dap_tests;
+using lldb_private::File;
+using lldb_private::NativeFile;
+using lldb_private::Pipe;
+
+void PipeBase::SetUp() {
+  ASSERT_THAT_ERROR(input.CreateNew(false).ToError(), Succeeded());
+  ASSERT_THAT_ERROR(output.CreateNew(false).ToError(), Succeeded());
+}
+
+void TransportBase::SetUp() {
+  PipeBase::SetUp();
+  to_dap = std::make_unique<Transport>(
+      "to_dap", nullptr,
+      std::make_shared<NativeFile>(input.GetReadFileDescriptor(),
+                                   File::eOpenOptionReadOnly,
+                                   NativeFile::Unowned),
+      std::make_shared<NativeFile>(output.GetWriteFileDescriptor(),
+                                   File::eOpenOptionWriteOnly,
+                                   NativeFile::Unowned));
+  from_dap = std::make_unique<Transport>(
+      "from_dap", nullptr,
+      std::make_shared<NativeFile>(output.GetReadFileDescriptor(),
+                                   File::eOpenOptionReadOnly,
+                                   NativeFile::Unowned),
+      std::make_shared<NativeFile>(input.GetWriteFileDescriptor(),
+                                   File::eOpenOptionWriteOnly,
+                                   NativeFile::Unowned));
+}
+
+void DAPTestBase::SetUp() {
+  TransportBase::SetUp();
+  dap = std::make_unique<DAP>(
+      /*log=*/nullptr,
+      /*default_repl_mode=*/ReplMode::Auto,
+      /*pre_init_commands=*/std::vector<std::string>(),
+      /*transport=*/*to_dap);
+}
+
+std::vector<Message> DAPTestBase::DrainOutput() {
+  std::vector<Message> msgs;
+  output.CloseWriteFileDescriptor();
+  while (true) {
+    Expected<Message> next = from_dap->Read(std::chrono::milliseconds(1));
+    if (!next) {
+      consumeError(next.takeError());
+      break;
+    }
+    msgs.push_back(*next);
+  }
+  return msgs;
+}
diff --git a/lldb/unittests/DAP/TestBase.h b/lldb/unittests/DAP/TestBase.h
new file mode 100644
index 000000000000..c789adf53c22
--- /dev/null
+++ b/lldb/unittests/DAP/TestBase.h
@@ -0,0 +1,48 @@
+//===-- TestBase.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 "DAP.h"
+#include "Protocol/ProtocolBase.h"
+#include "Transport.h"
+#include "lldb/Host/Pipe.h"
+#include "gtest/gtest.h"
+
+namespace lldb_dap_tests {
+
+/// A base class for tests that need a pair of pipes for communication.
+class PipeBase : public testing::Test {
+protected:
+  lldb_private::Pipe input;
+  lldb_private::Pipe output;
+
+  void SetUp() override;
+};
+
+/// A base class for tests that need transport configured for communicating DAP
+/// messages.
+class TransportBase : public PipeBase {
+protected:
+  std::unique_ptr<lldb_dap::Transport> to_dap;
+  std::unique_ptr<lldb_dap::Transport> from_dap;
+
+  void SetUp() override;
+};
+
+/// A base class for tests that interact with a `lldb_dap::DAP` instance.
+class DAPTestBase : public TransportBase {
+protected:
+  std::unique_ptr<lldb_dap::DAP> dap;
+
+  void SetUp() override;
+
+  /// Closes the DAP output pipe and returns the remaining protocol messages in
+  /// the buffer.
+  std::vector<lldb_dap::protocol::Message> DrainOutput();
+};
+
+} // namespace lldb_dap_tests
diff --git a/lldb/unittests/DAP/TransportTest.cpp b/lldb/unittests/DAP/TransportTest.cpp
index 5c77b4bb2634..e6dab42e3094 100644
--- a/lldb/unittests/DAP/TransportTest.cpp
+++ b/lldb/unittests/DAP/TransportTest.cpp
@@ -8,10 +8,10 @@
 
 #include "Transport.h"
 #include "Protocol/ProtocolBase.h"
+#include "TestBase.h"
 #include "lldb/Host/File.h"
 #include "lldb/Host/Pipe.h"
 #include "llvm/ADT/StringRef.h"
-#include "llvm/Support/FormatVariadic.h"
 #include "llvm/Testing/Support/Error.h"
 #include "gtest/gtest.h"
 #include <chrono>
@@ -21,20 +21,18 @@
 using namespace llvm;
 using namespace lldb;
 using namespace lldb_dap;
+using namespace lldb_dap_tests;
 using namespace lldb_dap::protocol;
 using lldb_private::File;
 using lldb_private::NativeFile;
 using lldb_private::Pipe;
 
-class TransportTest : public testing::Test {
+class TransportTest : public PipeBase {
 protected:
-  Pipe input;
-  Pipe output;
   std::unique_ptr<Transport> transport;
 
   void SetUp() override {
-    ASSERT_THAT_ERROR(input.CreateNew(false).ToError(), Succeeded());
-    ASSERT_THAT_ERROR(output.CreateNew(false).ToError(), Succeeded());
+    PipeBase::SetUp();
     transport = std::make_unique<Transport>(
         "stdio", nullptr,
         std::make_shared<NativeFile>(input.GetReadFileDescriptor(),
@@ -44,13 +42,6 @@ protected:
                                      File::eOpenOptionWriteOnly,
                                      NativeFile::Unowned));
   }
-
-  void Write(StringRef json) {
-    std::string message =
-        formatv("Content-Length: {0}\r\n\r\n{1}", json.size(), json).str();
-    ASSERT_THAT_EXPECTED(input.Write(message.data(), message.size()),
-                         Succeeded());
-  }
 };
 
 TEST_F(TransportTest, MalformedRequests) {
@@ -65,7 +56,12 @@ TEST_F(TransportTest, MalformedRequests) {
 }
 
 TEST_F(TransportTest, Read) {
-  Write(R"json({"seq": 1, "type": "request", "command": "abc"})json");
+  std::string json =
+      R"json({"seq": 1, "type": "request", "command": "abc"})json";
+  std::string message =
+      formatv("Content-Length: {0}\r\n\r\n{1}", json.size(), json).str();
+  ASSERT_THAT_EXPECTED(input.Write(message.data(), message.size()),
+                       Succeeded());
   ASSERT_THAT_EXPECTED(
       transport->Read(std::chrono::milliseconds(1)),
       HasValue(testing::VariantWith<Request>(testing::FieldsAre(