llvm-project/clang/unittests/Basic/FileManagerTest.cpp

//===- unittests/Basic/FileMangerTest.cpp ------------ FileManger 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 "clang/Basic/FileManager.h"
#include "clang/Basic/FileSystemOptions.h"
#include "clang/Basic/FileSystemStatCache.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/VirtualFileSystem.h"
#include "llvm/Testing/Support/Error.h"
#include "gtest/gtest.h"

using namespace llvm;
using namespace clang;

namespace {

// Used to create a fake file system for running the tests with such
// that the tests are not affected by the structure/contents of the
// file system on the machine running the tests.
class FakeStatCache : public FileSystemStatCache {
private:
  // Maps a file/directory path to its desired stat result.  Anything
  // not in this map is considered to not exist in the file system.
  llvm::StringMap<llvm::vfs::Status, llvm::BumpPtrAllocator> StatCalls;

  void InjectFileOrDirectory(const char *Path, ino_t INode, bool IsFile,
                             const char *StatPath) {
    SmallString<128> NormalizedPath(Path);
    SmallString<128> NormalizedStatPath;
    if (is_style_posix(llvm::sys::path::Style::native)) {
      llvm::sys::path::native(NormalizedPath);
      Path = NormalizedPath.c_str();

      if (StatPath) {
        NormalizedStatPath = StatPath;
        llvm::sys::path::native(NormalizedStatPath);
        StatPath = NormalizedStatPath.c_str();
      }
    }

    auto fileType = IsFile ?
      llvm::sys::fs::file_type::regular_file :
      llvm::sys::fs::file_type::directory_file;
    llvm::vfs::Status Status(StatPath ? StatPath : Path,
                             llvm::sys::fs::UniqueID(1, INode),
                             /*MTime*/{}, /*User*/0, /*Group*/0,
                             /*Size*/0, fileType,
                             llvm::sys::fs::perms::all_all);
    if (StatPath)
      Status.ExposesExternalVFSPath = true;
    StatCalls[Path] = Status;
  }

public:
  // Inject a file with the given inode value to the fake file system.
  void InjectFile(const char *Path, ino_t INode,
                  const char *StatPath = nullptr) {
    InjectFileOrDirectory(Path, INode, /*IsFile=*/true, StatPath);
  }

  // Inject a directory with the given inode value to the fake file system.
  void InjectDirectory(const char *Path, ino_t INode) {
    InjectFileOrDirectory(Path, INode, /*IsFile=*/false, nullptr);
  }

  // Implement FileSystemStatCache::getStat().
  std::error_code getStat(StringRef Path, llvm::vfs::Status &Status,
                          bool isFile,
                          std::unique_ptr<llvm::vfs::File> *F,
                          llvm::vfs::FileSystem &FS) override {
    SmallString<128> NormalizedPath(Path);
    if (is_style_posix(llvm::sys::path::Style::native)) {
      llvm::sys::path::native(NormalizedPath);
      Path = NormalizedPath.c_str();
    }

    if (StatCalls.count(Path) != 0) {
      Status = StatCalls[Path];
      return std::error_code();
    }

    return std::make_error_code(std::errc::no_such_file_or_directory);
  }
};

// The test fixture.
class FileManagerTest : public ::testing::Test {
 protected:
  FileManagerTest() : manager(options) {
  }

  FileSystemOptions options;
  FileManager manager;
};

// When a virtual file is added, its getDir() field has correct name.
TEST_F(FileManagerTest, getVirtualFileSetsTheDirFieldCorrectly) {
  FileEntryRef file = manager.getVirtualFileRef("foo.cpp", 42, 0);
  EXPECT_EQ(".", file.getDir().getName());

  file = manager.getVirtualFileRef("x/y/z.cpp", 42, 0);
  EXPECT_EQ("x/y", file.getDir().getName());
}

// Before any virtual file is added, no virtual directory exists.
TEST_F(FileManagerTest, NoVirtualDirectoryExistsBeforeAVirtualFileIsAdded) {
  // An empty FakeStatCache causes all stat calls made by the
  // FileManager to report "file/directory doesn't exist".  This
  // avoids the possibility of the result of this test being affected
  // by what's in the real file system.
  manager.setStatCache(std::make_unique<FakeStatCache>());

  ASSERT_FALSE(manager.getDirectory("virtual/dir/foo"));
  ASSERT_FALSE(manager.getDirectory("virtual/dir"));
  ASSERT_FALSE(manager.getDirectory("virtual"));
}

// When a virtual file is added, all of its ancestors should be created.
TEST_F(FileManagerTest, getVirtualFileCreatesDirectoryEntriesForAncestors) {
  // Fake an empty real file system.
  manager.setStatCache(std::make_unique<FakeStatCache>());

  manager.getVirtualFile("virtual/dir/bar.h", 100, 0);
  ASSERT_FALSE(manager.getDirectory("virtual/dir/foo"));

  auto dir = manager.getDirectoryRef("virtual/dir");
  ASSERT_THAT_EXPECTED(dir, llvm::Succeeded());
  EXPECT_EQ("virtual/dir", dir->getName());

  dir = manager.getDirectoryRef("virtual");
  ASSERT_THAT_EXPECTED(dir, llvm::Succeeded());
  EXPECT_EQ("virtual", dir->getName());
}

// getFileRef() succeeds if a real file exists at the given path.
TEST_F(FileManagerTest, getFileReturnsValidFileEntryForExistingRealFile) {
  // Inject fake files into the file system.
  auto statCache = std::make_unique<FakeStatCache>();
  statCache->InjectDirectory("/tmp", 42);
  statCache->InjectFile("/tmp/test", 43);

#ifdef _WIN32
  const char *DirName = "C:.";
  const char *FileName = "C:test";
  statCache->InjectDirectory(DirName, 44);
  statCache->InjectFile(FileName, 45);
#endif

  manager.setStatCache(std::move(statCache));

  auto file = manager.getFileRef("/tmp/test");
  ASSERT_THAT_EXPECTED(file, llvm::Succeeded());
  EXPECT_EQ("/tmp/test", file->getName());

  EXPECT_EQ("/tmp", file->getDir().getName());

#ifdef _WIN32
  file = manager.getFileRef(FileName);
  ASSERT_THAT_EXPECTED(file, llvm::Succeeded());
  EXPECT_EQ(DirName, file->getDir().getName());
#endif
}

// getFileRef() succeeds if a virtual file exists at the given path.
TEST_F(FileManagerTest, getFileReturnsValidFileEntryForExistingVirtualFile) {
  // Fake an empty real file system.
  manager.setStatCache(std::make_unique<FakeStatCache>());

  manager.getVirtualFile("virtual/dir/bar.h", 100, 0);
  auto file = manager.getFileRef("virtual/dir/bar.h");
  ASSERT_THAT_EXPECTED(file, llvm::Succeeded());
  EXPECT_EQ("virtual/dir/bar.h", file->getName());
  EXPECT_EQ("virtual/dir", file->getDir().getName());
}

// getFile() returns different FileEntries for different paths when
// there's no aliasing.
TEST_F(FileManagerTest, getFileReturnsDifferentFileEntriesForDifferentFiles) {
  // Inject two fake files into the file system.  Different inodes
  // mean the files are not symlinked together.
  auto statCache = std::make_unique<FakeStatCache>();
  statCache->InjectDirectory(".", 41);
  statCache->InjectFile("foo.cpp", 42);
  statCache->InjectFile("bar.cpp", 43);
  manager.setStatCache(std::move(statCache));

  auto fileFoo = manager.getFile("foo.cpp");
  auto fileBar = manager.getFile("bar.cpp");
  ASSERT_TRUE(fileFoo);
  ASSERT_TRUE(fileBar);
  EXPECT_NE(*fileFoo, *fileBar);
}

// getFile() returns an error if neither a real file nor a virtual file
// exists at the given path.
TEST_F(FileManagerTest, getFileReturnsErrorForNonexistentFile) {
  // Inject a fake foo.cpp into the file system.
  auto statCache = std::make_unique<FakeStatCache>();
  statCache->InjectDirectory(".", 41);
  statCache->InjectFile("foo.cpp", 42);
  statCache->InjectDirectory("MyDirectory", 49);
  manager.setStatCache(std::move(statCache));

  // Create a virtual bar.cpp file.
  manager.getVirtualFile("bar.cpp", 200, 0);

  auto file = manager.getFile("xyz.txt");
  ASSERT_FALSE(file);
  ASSERT_EQ(file.getError(), std::errc::no_such_file_or_directory);

  auto readingDirAsFile = manager.getFile("MyDirectory");
  ASSERT_FALSE(readingDirAsFile);
  ASSERT_EQ(readingDirAsFile.getError(), std::errc::is_a_directory);

  auto readingFileAsDir = manager.getDirectory("foo.cpp");
  ASSERT_FALSE(readingFileAsDir);
  ASSERT_EQ(readingFileAsDir.getError(), std::errc::not_a_directory);
}

// The following tests apply to Unix-like system only.

#ifndef _WIN32

// getFile() returns the same FileEntry for real files that are aliases.
TEST_F(FileManagerTest, getFileReturnsSameFileEntryForAliasedRealFiles) {
  // Inject two real files with the same inode.
  auto statCache = std::make_unique<FakeStatCache>();
  statCache->InjectDirectory("abc", 41);
  statCache->InjectFile("abc/foo.cpp", 42);
  statCache->InjectFile("abc/bar.cpp", 42);
  manager.setStatCache(std::move(statCache));

  auto f1 = manager.getFile("abc/foo.cpp");
  auto f2 = manager.getFile("abc/bar.cpp");

  EXPECT_EQ(f1 ? *f1 : nullptr,
            f2 ? *f2 : nullptr);

  // Check that getFileRef also does the right thing.
  auto r1 = manager.getFileRef("abc/foo.cpp");
  auto r2 = manager.getFileRef("abc/bar.cpp");
  ASSERT_FALSE(!r1);
  ASSERT_FALSE(!r2);

  EXPECT_EQ("abc/foo.cpp", r1->getName());
  EXPECT_EQ("abc/bar.cpp", r2->getName());
  EXPECT_EQ((f1 ? *f1 : nullptr), &r1->getFileEntry());
  EXPECT_EQ((f2 ? *f2 : nullptr), &r2->getFileEntry());
}

TEST_F(FileManagerTest, getFileRefReturnsCorrectNameForDifferentStatPath) {
  // Inject files with the same inode, but where some files have a stat that
  // gives a different name. This is adding coverage for stat behaviour
  // triggered by the RedirectingFileSystem for 'use-external-name' that
  // FileManager::getFileRef has special logic for.
  auto StatCache = std::make_unique<FakeStatCache>();
  StatCache->InjectDirectory("dir", 40);
  StatCache->InjectFile("dir/f1.cpp", 41);
  StatCache->InjectFile("dir/f1-alias.cpp", 41, "dir/f1.cpp");
  StatCache->InjectFile("dir/f2.cpp", 42);
  StatCache->InjectFile("dir/f2-alias.cpp", 42, "dir/f2.cpp");

  // This unintuitive rename-the-file-on-stat behaviour supports how the
  // RedirectingFileSystem VFS layer responds to stats. However, even if you
  // have two layers, you should only get a single filename back. As such the
  // following stat cache behaviour is not supported (the correct stat entry
  // for a double-redirection would be "dir/f1.cpp") and the getFileRef below
  // should assert.
  StatCache->InjectFile("dir/f1-alias-alias.cpp", 41, "dir/f1-alias.cpp");

  manager.setStatCache(std::move(StatCache));

  // With F1, test accessing the non-redirected name first.
  auto F1 = manager.getFileRef("dir/f1.cpp");
  auto F1Alias = manager.getFileRef("dir/f1-alias.cpp");
  auto F1Alias2 = manager.getFileRef("dir/f1-alias.cpp");
  ASSERT_FALSE(!F1);
  ASSERT_FALSE(!F1Alias);
  ASSERT_FALSE(!F1Alias2);
  EXPECT_EQ("dir/f1.cpp", F1->getName());
  LLVM_SUPPRESS_DEPRECATED_DECLARATIONS_PUSH
  EXPECT_EQ("dir/f1.cpp", F1->getFileEntry().getName());
  LLVM_SUPPRESS_DEPRECATED_DECLARATIONS_POP
  EXPECT_EQ("dir/f1.cpp", F1Alias->getName());
  EXPECT_EQ("dir/f1.cpp", F1Alias2->getName());
  EXPECT_EQ(&F1->getFileEntry(), &F1Alias->getFileEntry());
  EXPECT_EQ(&F1->getFileEntry(), &F1Alias2->getFileEntry());

#if !defined(NDEBUG) && GTEST_HAS_DEATH_TEST
  EXPECT_DEATH((void)manager.getFileRef("dir/f1-alias-alias.cpp"),
               "filename redirected to a non-canonical filename?");
#endif

  // With F2, test accessing the redirected name first.
  auto F2Alias = manager.getFileRef("dir/f2-alias.cpp");
  auto F2 = manager.getFileRef("dir/f2.cpp");
  auto F2Alias2 = manager.getFileRef("dir/f2-alias.cpp");
  ASSERT_FALSE(!F2);
  ASSERT_FALSE(!F2Alias);
  ASSERT_FALSE(!F2Alias2);
  EXPECT_EQ("dir/f2.cpp", F2->getName());
  LLVM_SUPPRESS_DEPRECATED_DECLARATIONS_PUSH
  EXPECT_EQ("dir/f2.cpp", F2->getFileEntry().getName());
  LLVM_SUPPRESS_DEPRECATED_DECLARATIONS_POP
  EXPECT_EQ("dir/f2.cpp", F2Alias->getName());
  EXPECT_EQ("dir/f2.cpp", F2Alias2->getName());
  EXPECT_EQ(&F2->getFileEntry(), &F2Alias->getFileEntry());
  EXPECT_EQ(&F2->getFileEntry(), &F2Alias2->getFileEntry());
}

TEST_F(FileManagerTest, getFileRefReturnsCorrectDirNameForDifferentStatPath) {
  // Inject files with the same inode into distinct directories (name & inode).
  auto StatCache = std::make_unique<FakeStatCache>();
  StatCache->InjectDirectory("dir1", 40);
  StatCache->InjectDirectory("dir2", 41);
  StatCache->InjectFile("dir1/f.cpp", 42);
  StatCache->InjectFile("dir2/f.cpp", 42, "dir1/f.cpp");

  manager.setStatCache(std::move(StatCache));
  auto Dir1F = manager.getFileRef("dir1/f.cpp");
  auto Dir2F = manager.getFileRef("dir2/f.cpp");

  ASSERT_FALSE(!Dir1F);
  ASSERT_FALSE(!Dir2F);
  EXPECT_EQ("dir1", Dir1F->getDir().getName());
  EXPECT_EQ("dir2", Dir2F->getDir().getName());
  EXPECT_EQ("dir1/f.cpp", Dir1F->getNameAsRequested());
  EXPECT_EQ("dir2/f.cpp", Dir2F->getNameAsRequested());
}

// getFile() returns the same FileEntry for virtual files that have
// corresponding real files that are aliases.
TEST_F(FileManagerTest, getFileReturnsSameFileEntryForAliasedVirtualFiles) {
  // Inject two real files with the same inode.
  auto statCache = std::make_unique<FakeStatCache>();
  statCache->InjectDirectory("abc", 41);
  statCache->InjectFile("abc/foo.cpp", 42);
  statCache->InjectFile("abc/bar.cpp", 42);
  manager.setStatCache(std::move(statCache));

  auto f1 = manager.getFile("abc/foo.cpp");
  auto f2 = manager.getFile("abc/bar.cpp");

  EXPECT_EQ(f1 ? *f1 : nullptr,
            f2 ? *f2 : nullptr);
}

TEST_F(FileManagerTest, getFileRefEquality) {
  auto StatCache = std::make_unique<FakeStatCache>();
  StatCache->InjectDirectory("dir", 40);
  StatCache->InjectFile("dir/f1.cpp", 41);
  StatCache->InjectFile("dir/f1-also.cpp", 41);
  StatCache->InjectFile("dir/f1-redirect.cpp", 41, "dir/f1.cpp");
  StatCache->InjectFile("dir/f2.cpp", 42);
  manager.setStatCache(std::move(StatCache));

  auto F1 = manager.getFileRef("dir/f1.cpp");
  auto F1Again = manager.getFileRef("dir/f1.cpp");
  auto F1Also = manager.getFileRef("dir/f1-also.cpp");
  auto F1Redirect = manager.getFileRef("dir/f1-redirect.cpp");
  auto F1RedirectAgain = manager.getFileRef("dir/f1-redirect.cpp");
  auto F2 = manager.getFileRef("dir/f2.cpp");

  // Check Expected<FileEntryRef> for error.
  ASSERT_FALSE(!F1);
  ASSERT_FALSE(!F1Also);
  ASSERT_FALSE(!F1Again);
  ASSERT_FALSE(!F1Redirect);
  ASSERT_FALSE(!F1RedirectAgain);
  ASSERT_FALSE(!F2);

  // Check names.
  EXPECT_EQ("dir/f1.cpp", F1->getName());
  EXPECT_EQ("dir/f1.cpp", F1Again->getName());
  EXPECT_EQ("dir/f1-also.cpp", F1Also->getName());
  EXPECT_EQ("dir/f1.cpp", F1Redirect->getName());
  EXPECT_EQ("dir/f1.cpp", F1RedirectAgain->getName());
  EXPECT_EQ("dir/f2.cpp", F2->getName());

  EXPECT_EQ("dir/f1.cpp", F1->getNameAsRequested());
  EXPECT_EQ("dir/f1-redirect.cpp", F1Redirect->getNameAsRequested());

  // Compare against FileEntry*.
  EXPECT_EQ(&F1->getFileEntry(), *F1);
  EXPECT_EQ(*F1, &F1->getFileEntry());
  EXPECT_EQ(&F1->getFileEntry(), &F1Redirect->getFileEntry());
  EXPECT_EQ(&F1->getFileEntry(), &F1RedirectAgain->getFileEntry());
  EXPECT_NE(&F2->getFileEntry(), *F1);
  EXPECT_NE(*F1, &F2->getFileEntry());

  // Compare using ==.
  EXPECT_EQ(*F1, *F1Also);
  EXPECT_EQ(*F1, *F1Again);
  EXPECT_EQ(*F1, *F1Redirect);
  EXPECT_EQ(*F1Also, *F1Redirect);
  EXPECT_EQ(*F1, *F1RedirectAgain);
  EXPECT_NE(*F2, *F1);
  EXPECT_NE(*F2, *F1Also);
  EXPECT_NE(*F2, *F1Again);
  EXPECT_NE(*F2, *F1Redirect);

  // Compare using isSameRef.
  EXPECT_TRUE(F1->isSameRef(*F1Again));
  EXPECT_FALSE(F1->isSameRef(*F1Redirect));
  EXPECT_FALSE(F1->isSameRef(*F1Also));
  EXPECT_FALSE(F1->isSameRef(*F2));
  EXPECT_TRUE(F1Redirect->isSameRef(*F1RedirectAgain));
}

// getFile() Should return the same entry as getVirtualFile if the file actually
// is a virtual file, even if the name is not exactly the same (but is after
// normalisation done by the file system, like on Windows). This can be checked
// here by checking the size.
TEST_F(FileManagerTest, getVirtualFileWithDifferentName) {
  // Inject fake files into the file system.
  auto statCache = std::make_unique<FakeStatCache>();
  statCache->InjectDirectory("c:\\tmp", 42);
  statCache->InjectFile("c:\\tmp\\test", 43);

  manager.setStatCache(std::move(statCache));

  // Inject the virtual file:
  const FileEntry *file1 = manager.getVirtualFile("c:\\tmp\\test", 123, 1);
  ASSERT_TRUE(file1 != nullptr);
  EXPECT_EQ(43U, file1->getUniqueID().getFile());
  EXPECT_EQ(123, file1->getSize());

  // Lookup the virtual file with a different name:
  auto file2 = manager.getFile("c:/tmp/test", 100, 1);
  ASSERT_TRUE(file2);
  // Check that it's the same UFE:
  EXPECT_EQ(file1, *file2);
  EXPECT_EQ(43U, (*file2)->getUniqueID().getFile());
  // Check that the contents of the UFE are not overwritten by the entry in the
  // filesystem:
  EXPECT_EQ(123, (*file2)->getSize());
}

#endif  // !_WIN32

static StringRef getSystemRoot() {
  return is_style_windows(llvm::sys::path::Style::native) ? "C:\\" : "/";
}

TEST_F(FileManagerTest, makeAbsoluteUsesVFS) {
  // FIXME: Should this be using a root path / call getSystemRoot()? For now,
  // avoiding that and leaving the test as-is.
  SmallString<64> CustomWorkingDir =
      is_style_windows(llvm::sys::path::Style::native) ? StringRef("C:")
                                                       : StringRef("/");
  llvm::sys::path::append(CustomWorkingDir, "some", "weird", "path");

  auto FS = IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem>(
      new llvm::vfs::InMemoryFileSystem);
  // setCurrentworkingdirectory must finish without error.
  ASSERT_TRUE(!FS->setCurrentWorkingDirectory(CustomWorkingDir));

  FileSystemOptions Opts;
  FileManager Manager(Opts, FS);

  SmallString<64> Path("a/foo.cpp");

  SmallString<64> ExpectedResult(CustomWorkingDir);
  llvm::sys::path::append(ExpectedResult, Path);

  ASSERT_TRUE(Manager.makeAbsolutePath(Path));
  EXPECT_EQ(Path, ExpectedResult);
}

// getVirtualFile should always fill the real path.
TEST_F(FileManagerTest, getVirtualFileFillsRealPathName) {
  SmallString<64> CustomWorkingDir = getSystemRoot();

  auto FS = IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem>(
      new llvm::vfs::InMemoryFileSystem);
  // setCurrentworkingdirectory must finish without error.
  ASSERT_TRUE(!FS->setCurrentWorkingDirectory(CustomWorkingDir));

  FileSystemOptions Opts;
  FileManager Manager(Opts, FS);

  // Inject fake files into the file system.
  auto statCache = std::make_unique<FakeStatCache>();
  statCache->InjectDirectory("/tmp", 42);
  statCache->InjectFile("/tmp/test", 43);

  Manager.setStatCache(std::move(statCache));

  // Check for real path.
  const FileEntry *file = Manager.getVirtualFile("/tmp/test", 123, 1);
  ASSERT_TRUE(file != nullptr);
  SmallString<64> ExpectedResult = CustomWorkingDir;

  llvm::sys::path::append(ExpectedResult, "tmp", "test");
  EXPECT_EQ(file->tryGetRealPathName(), ExpectedResult);
}

TEST_F(FileManagerTest, getFileDontOpenRealPath) {
  SmallString<64> CustomWorkingDir = getSystemRoot();

  auto FS = IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem>(
      new llvm::vfs::InMemoryFileSystem);
  // setCurrentworkingdirectory must finish without error.
  ASSERT_TRUE(!FS->setCurrentWorkingDirectory(CustomWorkingDir));

  FileSystemOptions Opts;
  FileManager Manager(Opts, FS);

  // Inject fake files into the file system.
  auto statCache = std::make_unique<FakeStatCache>();
  statCache->InjectDirectory("/tmp", 42);
  statCache->InjectFile("/tmp/test", 43);

  Manager.setStatCache(std::move(statCache));

  // Check for real path.
  auto file = Manager.getFile("/tmp/test", /*OpenFile=*/false);
  ASSERT_TRUE(file);
  SmallString<64> ExpectedResult = CustomWorkingDir;

  llvm::sys::path::append(ExpectedResult, "tmp", "test");
  EXPECT_EQ((*file)->tryGetRealPathName(), ExpectedResult);
}

TEST_F(FileManagerTest, getBypassFile) {
  SmallString<64> CustomWorkingDir;
#ifdef _WIN32
  CustomWorkingDir = "C:/";
#else
  CustomWorkingDir = "/";
#endif

  auto FS = IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem>(
      new llvm::vfs::InMemoryFileSystem);
  // setCurrentworkingdirectory must finish without error.
  ASSERT_TRUE(!FS->setCurrentWorkingDirectory(CustomWorkingDir));

  FileSystemOptions Opts;
  FileManager Manager(Opts, FS);

  // Inject fake files into the file system.
  auto Cache = std::make_unique<FakeStatCache>();
  Cache->InjectDirectory("/tmp", 42);
  Cache->InjectFile("/tmp/test", 43);
  Manager.setStatCache(std::move(Cache));

  // Set up a virtual file with a different size than FakeStatCache uses.
  FileEntryRef File = Manager.getVirtualFileRef("/tmp/test", /*Size=*/10, 0);
  ASSERT_TRUE(File);
  const FileEntry &FE = *File;
  EXPECT_EQ(FE.getSize(), 10);

  // Calling a second time should not affect the UID or size.
  unsigned VirtualUID = FE.getUID();
  OptionalFileEntryRef SearchRef;
  ASSERT_THAT_ERROR(Manager.getFileRef("/tmp/test").moveInto(SearchRef),
                    Succeeded());
  EXPECT_EQ(&FE, &SearchRef->getFileEntry());
  EXPECT_EQ(FE.getUID(), VirtualUID);
  EXPECT_EQ(FE.getSize(), 10);

  // Bypass the file.
  OptionalFileEntryRef BypassRef = Manager.getBypassFile(File);
  ASSERT_TRUE(BypassRef);
  EXPECT_EQ("/tmp/test", BypassRef->getName());

  // Check that it's different in the right ways.
  EXPECT_NE(&BypassRef->getFileEntry(), File);
  EXPECT_NE(BypassRef->getUID(), VirtualUID);
  EXPECT_NE(BypassRef->getSize(), FE.getSize());

  // The virtual file should still be returned when searching.
  ASSERT_THAT_ERROR(Manager.getFileRef("/tmp/test").moveInto(SearchRef),
                    Succeeded());
  EXPECT_EQ(&FE, &SearchRef->getFileEntry());
}

} // anonymous namespace