[clang-tools-extra] [clangd] [C++20] [Modules] Introduce initial support for C++20 Modules (PR #66462)

[kadir çetinkaya via cfe-commits]

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@@ -0,0 +1,355 @@
+//===--------------- PrerequisiteModulesTests.cpp -------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+/// FIXME: Skip testing on windows temporarily due to the different escaping
+/// code mode.
+#ifndef _WIN32
+
+#include "ModulesBuilder.h"
+#include "ScanningProjectModules.h"
+
+#include "Annotations.h"
+#include "CodeComplete.h"
+#include "Compiler.h"
+#include "TestTU.h"
+#include "support/ThreadsafeFS.h"
+
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/raw_ostream.h"
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+
+namespace clang::clangd {
+namespace {
+
+class MockDirectoryCompilationDatabase : public MockCompilationDatabase {
+public:
+  MockDirectoryCompilationDatabase(StringRef TestDir, const ThreadsafeFS &TFS)
+      : MockCompilationDatabase(TestDir),
+        MockedCDBPtr(std::make_shared<MockClangCompilationDatabase>(*this)),
+        TFS(TFS) {
+    this->ExtraClangFlags.push_back("-std=c++20");
+    this->ExtraClangFlags.push_back("-c");
+  }
+
+  void addFile(llvm::StringRef Path, llvm::StringRef Contents);
+
+  std::unique_ptr<ProjectModules> getProjectModules(PathRef) const override {
+    return scanningProjectModules(MockedCDBPtr, TFS);
+  }
+
+private:
+  class MockClangCompilationDatabase : public tooling::CompilationDatabase {
+  public:
+    MockClangCompilationDatabase(MockDirectoryCompilationDatabase &MCDB)
+        : MCDB(MCDB) {}
+
+    std::vector<tooling::CompileCommand>
+    getCompileCommands(StringRef FilePath) const override {
+      std::optional<tooling::CompileCommand> Cmd =
+          MCDB.getCompileCommand(FilePath);
+      EXPECT_TRUE(Cmd);
+      return {*Cmd};
+    }
+
+    std::vector<std::string> getAllFiles() const override { return Files; }
+
+    void AddFile(StringRef File) { Files.push_back(File.str()); }
+
+  private:
+    MockDirectoryCompilationDatabase &MCDB;
+    std::vector<std::string> Files;
+  };
+
+  std::shared_ptr<MockClangCompilationDatabase> MockedCDBPtr;
+  const ThreadsafeFS &TFS;
+};
+
+// Add files to the working testing directory and the compilation database.
+void MockDirectoryCompilationDatabase::addFile(llvm::StringRef Path,
+                                               llvm::StringRef Contents) {
+  ASSERT_FALSE(llvm::sys::path::is_absolute(Path));
+
+  SmallString<256> AbsPath(Directory);
+  llvm::sys::path::append(AbsPath, Path);
+
+  ASSERT_FALSE(
+      llvm::sys::fs::create_directories(llvm::sys::path::parent_path(AbsPath)));
+
+  std::error_code EC;
+  llvm::raw_fd_ostream OS(AbsPath, EC);
+  ASSERT_FALSE(EC);
+  OS << Contents;
+
+  MockedCDBPtr->AddFile(Path);
+}
+
+class PrerequisiteModulesTests : public ::testing::Test {
+protected:
+  void SetUp() override {
+    ASSERT_FALSE(llvm::sys::fs::createUniqueDirectory("modules-test", TestDir));
+  }
+
+  void TearDown() override {
+    ASSERT_FALSE(llvm::sys::fs::remove_directories(TestDir));
+  }
+
+public:
+  // Get the absolute path for file specified by Path under testing working
+  // directory.
+  std::string getFullPath(llvm::StringRef Path) {
+    SmallString<128> Result(TestDir);
+    llvm::sys::path::append(Result, Path);
+    EXPECT_TRUE(llvm::sys::fs::exists(Result.str()));
+    return Result.str().str();
+  }
+
+  std::unique_ptr<GlobalCompilationDatabase> getGlobalCompilationDatabase() {
+    // The compilation flags with modules are much complex so it looks better
+    // to use DirectoryBasedGlobalCompilationDatabase than a mocked compilation
+    // database.
+    DirectoryBasedGlobalCompilationDatabase::Options Opts(TFS);
+    return std::make_unique<DirectoryBasedGlobalCompilationDatabase>(Opts);
+  }
+
+  ParseInputs getInputs(llvm::StringRef FileName,
+                        const GlobalCompilationDatabase &CDB) {
+    std::string FullPathName = getFullPath(FileName);
+
+    ParseInputs Inputs;
+    std::optional<tooling::CompileCommand> Cmd =
+        CDB.getCompileCommand(FullPathName);
+    EXPECT_TRUE(Cmd);
+    Inputs.CompileCommand = std::move(*Cmd);
+    Inputs.TFS = &TFS;
+
+    if (auto Contents = TFS.view(TestDir)->getBufferForFile(FullPathName))
+      Inputs.Contents = Contents->get()->getBuffer().str();
+
+    return Inputs;
+  }
+
+  SmallString<256> TestDir;
+  // Noticed MockFS but its member variable 'OverlayRealFileSystemForModules'
+  // implies that it will better to use RealThreadsafeFS directly.
----------------
kadircet wrote:

not sure i follow the reasoning here, isn't it precisely better to use MockFS because of that?

e.g. we can put all the sources needed by tests into virtual-fs and let pcms be written/read from realfs. this gets rid of both unnecessary real io for tests and makes sure we don't leave artifacts behind when something goes wrong.

https://github.com/llvm/llvm-project/pull/66462