clang/unittests/Basic/VirtualFileSystemTest.cpp

//===- unittests/Basic/VirtualFileSystem.cpp ---------------- VFS tests ---===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "clang/Basic/VirtualFileSystem.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/SourceMgr.h"
#include "gtest/gtest.h"
#include <map>
using namespace clang;
using namespace llvm;
using llvm::sys::fs::UniqueID;

namespace {
class DummyFileSystem : public vfs::FileSystem {
  int FSID;   // used to produce UniqueIDs
  int FileID; // used to produce UniqueIDs
  std::map<std::string, vfs::Status> FilesAndDirs;

  static int getNextFSID() {
    static int Count = 0;
    return Count++;
  }

public:
  DummyFileSystem() : FSID(getNextFSID()), FileID(0) {}

  ErrorOr<vfs::Status> status(const Twine &Path) {
    std::map<std::string, vfs::Status>::iterator I =
        FilesAndDirs.find(Path.str());
    if (I == FilesAndDirs.end())
      return make_error_code(llvm::errc::no_such_file_or_directory);
    return I->second;
  }
  std::error_code openFileForRead(const Twine &Path,
                                  std::unique_ptr<vfs::File> &Result) {
    llvm_unreachable("unimplemented");
  }
  std::error_code getBufferForFile(const Twine &Name,
                                   std::unique_ptr<MemoryBuffer> &Result,
                                   int64_t FileSize = -1,
                                   bool RequiresNullTerminator = true) {
    llvm_unreachable("unimplemented");
  }

  struct DirIterImpl : public clang::vfs::detail::DirIterImpl {
    std::map<std::string, vfs::Status> &FilesAndDirs;
    std::map<std::string, vfs::Status>::iterator I;
    std::string Path;
    DirIterImpl(std::map<std::string, vfs::Status> &FilesAndDirs,
                const Twine &_Path)
        : FilesAndDirs(FilesAndDirs), I(FilesAndDirs.begin()),
          Path(_Path.str()) {
      for ( ; I != FilesAndDirs.end(); ++I) {
        if (Path.size() < I->first.size() && I->first.find(Path) == 0 && I->first.find_last_of('/') <= Path.size()) {
          CurrentEntry = I->second;
          break;
        }
      }
    }
    std::error_code increment() override {
      ++I;
      for ( ; I != FilesAndDirs.end(); ++I) {
        if (Path.size() < I->first.size() && I->first.find(Path) == 0 && I->first.find_last_of('/') <= Path.size()) {
          CurrentEntry = I->second;
          break;
        }
      }
      if (I == FilesAndDirs.end())
        CurrentEntry = vfs::Status();
      return std::error_code();
    }
  };

  vfs::directory_iterator dir_begin(const Twine &Dir,
                                    std::error_code &EC) override {
    return vfs::directory_iterator(
        std::make_shared<DirIterImpl>(FilesAndDirs, Dir));
  }

  void addEntry(StringRef Path, const vfs::Status &Status) {
    FilesAndDirs[Path] = Status;
  }

  void addRegularFile(StringRef Path, sys::fs::perms Perms = sys::fs::all_all) {
    vfs::Status S(Path, Path, UniqueID(FSID, FileID++), sys::TimeValue::now(),
                  0, 0, 1024, sys::fs::file_type::regular_file, Perms);
    addEntry(Path, S);
  }

  void addDirectory(StringRef Path, sys::fs::perms Perms = sys::fs::all_all) {
    vfs::Status S(Path, Path, UniqueID(FSID, FileID++), sys::TimeValue::now(),
                  0, 0, 0, sys::fs::file_type::directory_file, Perms);
    addEntry(Path, S);
  }

  void addSymlink(StringRef Path) {
    vfs::Status S(Path, Path, UniqueID(FSID, FileID++), sys::TimeValue::now(),
                  0, 0, 0, sys::fs::file_type::symlink_file, sys::fs::all_all);
    addEntry(Path, S);
  }
};
} // end anonymous namespace

TEST(VirtualFileSystemTest, StatusQueries) {
  IntrusiveRefCntPtr<DummyFileSystem> D(new DummyFileSystem());
  ErrorOr<vfs::Status> Status((std::error_code()));

  D->addRegularFile("/foo");
  Status = D->status("/foo");
  ASSERT_FALSE(Status.getError());
  EXPECT_TRUE(Status->isStatusKnown());
  EXPECT_FALSE(Status->isDirectory());
  EXPECT_TRUE(Status->isRegularFile());
  EXPECT_FALSE(Status->isSymlink());
  EXPECT_FALSE(Status->isOther());
  EXPECT_TRUE(Status->exists());

  D->addDirectory("/bar");
  Status = D->status("/bar");
  ASSERT_FALSE(Status.getError());
  EXPECT_TRUE(Status->isStatusKnown());
  EXPECT_TRUE(Status->isDirectory());
  EXPECT_FALSE(Status->isRegularFile());
  EXPECT_FALSE(Status->isSymlink());
  EXPECT_FALSE(Status->isOther());
  EXPECT_TRUE(Status->exists());

  D->addSymlink("/baz");
  Status = D->status("/baz");
  ASSERT_FALSE(Status.getError());
  EXPECT_TRUE(Status->isStatusKnown());
  EXPECT_FALSE(Status->isDirectory());
  EXPECT_FALSE(Status->isRegularFile());
  EXPECT_TRUE(Status->isSymlink());
  EXPECT_FALSE(Status->isOther());
  EXPECT_TRUE(Status->exists());

  EXPECT_TRUE(Status->equivalent(*Status));
  ErrorOr<vfs::Status> Status2 = D->status("/foo");
  ASSERT_FALSE(Status2.getError());
  EXPECT_FALSE(Status->equivalent(*Status2));
}

TEST(VirtualFileSystemTest, BaseOnlyOverlay) {
  IntrusiveRefCntPtr<DummyFileSystem> D(new DummyFileSystem());
  ErrorOr<vfs::Status> Status((std::error_code()));
  EXPECT_FALSE(Status = D->status("/foo"));

  IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(new vfs::OverlayFileSystem(D));
  EXPECT_FALSE(Status = O->status("/foo"));

  D->addRegularFile("/foo");
  Status = D->status("/foo");
  EXPECT_FALSE(Status.getError());

  ErrorOr<vfs::Status> Status2((std::error_code()));
  Status2 = O->status("/foo");
  EXPECT_FALSE(Status2.getError());
  EXPECT_TRUE(Status->equivalent(*Status2));
}

TEST(VirtualFileSystemTest, OverlayFiles) {
  IntrusiveRefCntPtr<DummyFileSystem> Base(new DummyFileSystem());
  IntrusiveRefCntPtr<DummyFileSystem> Middle(new DummyFileSystem());
  IntrusiveRefCntPtr<DummyFileSystem> Top(new DummyFileSystem());
  IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
      new vfs::OverlayFileSystem(Base));
  O->pushOverlay(Middle);
  O->pushOverlay(Top);

  ErrorOr<vfs::Status> Status1((std::error_code())),
      Status2((std::error_code())), Status3((std::error_code())),
      StatusB((std::error_code())), StatusM((std::error_code())),
      StatusT((std::error_code()));

  Base->addRegularFile("/foo");
  StatusB = Base->status("/foo");
  ASSERT_FALSE(StatusB.getError());
  Status1 = O->status("/foo");
  ASSERT_FALSE(Status1.getError());
  Middle->addRegularFile("/foo");
  StatusM = Middle->status("/foo");
  ASSERT_FALSE(StatusM.getError());
  Status2 = O->status("/foo");
  ASSERT_FALSE(Status2.getError());
  Top->addRegularFile("/foo");
  StatusT = Top->status("/foo");
  ASSERT_FALSE(StatusT.getError());
  Status3 = O->status("/foo");
  ASSERT_FALSE(Status3.getError());

  EXPECT_TRUE(Status1->equivalent(*StatusB));
  EXPECT_TRUE(Status2->equivalent(*StatusM));
  EXPECT_TRUE(Status3->equivalent(*StatusT));

  EXPECT_FALSE(Status1->equivalent(*Status2));
  EXPECT_FALSE(Status2->equivalent(*Status3));
  EXPECT_FALSE(Status1->equivalent(*Status3));
}

TEST(VirtualFileSystemTest, OverlayDirsNonMerged) {
  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
  IntrusiveRefCntPtr<DummyFileSystem> Upper(new DummyFileSystem());
  IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
      new vfs::OverlayFileSystem(Lower));
  O->pushOverlay(Upper);

  Lower->addDirectory("/lower-only");
  Upper->addDirectory("/upper-only");

  // non-merged paths should be the same
  ErrorOr<vfs::Status> Status1 = Lower->status("/lower-only");
  ASSERT_FALSE(Status1.getError());
  ErrorOr<vfs::Status> Status2 = O->status("/lower-only");
  ASSERT_FALSE(Status2.getError());
  EXPECT_TRUE(Status1->equivalent(*Status2));

  Status1 = Upper->status("/upper-only");
  ASSERT_FALSE(Status1.getError());
  Status2 = O->status("/upper-only");
  ASSERT_FALSE(Status2.getError());
  EXPECT_TRUE(Status1->equivalent(*Status2));
}

TEST(VirtualFileSystemTest, MergedDirPermissions) {
  // merged directories get the permissions of the upper dir
  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
  IntrusiveRefCntPtr<DummyFileSystem> Upper(new DummyFileSystem());
  IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
      new vfs::OverlayFileSystem(Lower));
  O->pushOverlay(Upper);

  ErrorOr<vfs::Status> Status((std::error_code()));
  Lower->addDirectory("/both", sys::fs::owner_read);
  Upper->addDirectory("/both", sys::fs::owner_all | sys::fs::group_read);
  Status = O->status("/both");
  ASSERT_FALSE(Status.getError());
  EXPECT_EQ(0740, Status->getPermissions());

  // permissions (as usual) are not recursively applied
  Lower->addRegularFile("/both/foo", sys::fs::owner_read);
  Upper->addRegularFile("/both/bar", sys::fs::owner_write);
  Status = O->status("/both/foo");
  ASSERT_FALSE( Status.getError());
  EXPECT_EQ(0400, Status->getPermissions());
  Status = O->status("/both/bar");
  ASSERT_FALSE(Status.getError());
  EXPECT_EQ(0200, Status->getPermissions());
}

namespace {
struct ScopedDir {
  SmallString<128> Path;
  ScopedDir(const Twine &Name, bool Unique=false) {
    std::error_code EC;
    if (Unique) {
      EC =  llvm::sys::fs::createUniqueDirectory(Name, Path);
    } else {
      Path = Name.str();
      EC = llvm::sys::fs::create_directory(Twine(Path));
    }
    if (EC)
      Path = "";
    EXPECT_FALSE(EC);
  }
  ~ScopedDir() {
    if (Path != "")
      EXPECT_FALSE(llvm::sys::fs::remove(Path.str()));
  }
  operator StringRef() { return Path.str(); }
};
}

TEST(VirtualFileSystemTest, BasicRealFSIteration) {
  ScopedDir TestDirectory("virtual-file-system-test", /*Unique*/true);
  IntrusiveRefCntPtr<vfs::FileSystem> FS = vfs::getRealFileSystem();

  std::error_code EC;
  vfs::directory_iterator I = FS->dir_begin(Twine(TestDirectory), EC);
  ASSERT_FALSE(EC);
  EXPECT_EQ(vfs::directory_iterator(), I); // empty directory is empty

  ScopedDir _a(TestDirectory+"/a");
  ScopedDir _ab(TestDirectory+"/a/b");
  ScopedDir _c(TestDirectory+"/c");
  ScopedDir _cd(TestDirectory+"/c/d");

  I = FS->dir_begin(Twine(TestDirectory), EC);
  ASSERT_FALSE(EC);
  ASSERT_NE(vfs::directory_iterator(), I);
  EXPECT_TRUE(I->getName().endswith("a"));
  I.increment(EC);
  ASSERT_FALSE(EC);
  ASSERT_NE(vfs::directory_iterator(), I);
  EXPECT_TRUE(I->getName().endswith("c"));
  I.increment(EC);
  EXPECT_EQ(vfs::directory_iterator(), I);
}

static void checkContents(vfs::directory_iterator I,
                          ArrayRef<std::string> Expected) {
  std::error_code EC;
  auto ExpectedIter = Expected.begin(), ExpectedEnd = Expected.end();
  for (vfs::directory_iterator E;
       !EC && I != E && ExpectedIter != ExpectedEnd;
       I.increment(EC), ++ExpectedIter)
    EXPECT_EQ(*ExpectedIter, I->getName());

  EXPECT_EQ(ExpectedEnd, ExpectedIter);
  EXPECT_EQ(vfs::directory_iterator(), I);
}

TEST(VirtualFileSystemTest, OverlayIteration) {
  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
  IntrusiveRefCntPtr<DummyFileSystem> Upper(new DummyFileSystem());
  IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
      new vfs::OverlayFileSystem(Lower));
  O->pushOverlay(Upper);

  std::error_code EC;
  checkContents(O->dir_begin("/", EC), ArrayRef<std::string>());

  Lower->addRegularFile("/file1");
  checkContents(O->dir_begin("/", EC), ArrayRef<std::string>("/file1"));

  Upper->addRegularFile("/file2");
  {
    std::vector<std::string> Contents = { "/file2", "/file1" };
    checkContents(O->dir_begin("/", EC), Contents);
  }

  Lower->addDirectory("/dir1");
  Lower->addRegularFile("/dir1/foo");
  Upper->addDirectory("/dir2");
  Upper->addRegularFile("/dir2/foo");
  checkContents(O->dir_begin("/dir2", EC), ArrayRef<std::string>("/dir2/foo"));
  {
    std::vector<std::string> Contents = { "/dir2", "/file2", "/dir1", "/file1" };
    checkContents(O->dir_begin("/", EC), Contents);
  }
}

TEST(VirtualFileSystemTest, ThreeLevelIteration) {
  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
  IntrusiveRefCntPtr<DummyFileSystem> Middle(new DummyFileSystem());
  IntrusiveRefCntPtr<DummyFileSystem> Upper(new DummyFileSystem());
  IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
      new vfs::OverlayFileSystem(Lower));
  O->pushOverlay(Middle);
  O->pushOverlay(Upper);

  std::error_code EC;
  checkContents(O->dir_begin("/", EC), ArrayRef<std::string>());

  Middle->addRegularFile("/file2");
  checkContents(O->dir_begin("/", EC), ArrayRef<std::string>("/file2"));

  Lower->addRegularFile("/file1");
  Upper->addRegularFile("/file3");
  {
    std::vector<std::string> Contents = { "/file3", "/file2", "/file1" };
    checkContents(O->dir_begin("/", EC), Contents);
  }
}

TEST(VirtualFileSystemTest, HiddenInIteration) {
  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
  IntrusiveRefCntPtr<DummyFileSystem> Middle(new DummyFileSystem());
  IntrusiveRefCntPtr<DummyFileSystem> Upper(new DummyFileSystem());
  IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
      new vfs::OverlayFileSystem(Lower));
  O->pushOverlay(Middle);
  O->pushOverlay(Upper);

  std::error_code EC;
  Lower->addRegularFile("/onlyInLow", sys::fs::owner_read);
  Lower->addRegularFile("/hiddenByMid", sys::fs::owner_read);
  Lower->addRegularFile("/hiddenByUp", sys::fs::owner_read);
  Middle->addRegularFile("/onlyInMid", sys::fs::owner_write);
  Middle->addRegularFile("/hiddenByMid", sys::fs::owner_write);
  Middle->addRegularFile("/hiddenByUp", sys::fs::owner_write);
  Upper->addRegularFile("/onlyInUp", sys::fs::owner_all);
  Upper->addRegularFile("/hiddenByUp", sys::fs::owner_all);
  {
    std::vector<std::string> Contents = { "/hiddenByUp", "/onlyInUp",
        "/hiddenByMid", "/onlyInMid", "/onlyInLow" };
    checkContents(O->dir_begin("/", EC), Contents);
  }

  // FIXME: broke gcc build
  // Make sure we get the top-most entry
  // vfs::directory_iterator E;
  // {
  //   auto I = std::find_if(O->dir_begin("/", EC), E, [](vfs::Status S){
  //     return S.getName() == "/hiddenByUp";
  //   });
  //   ASSERT_NE(E, I);
  //   EXPECT_EQ(sys::fs::owner_all, I->getPermissions());
  // }
  // {
  //   auto I = std::find_if(O->dir_begin("/", EC), E, [](vfs::Status S){
  //     return S.getName() == "/hiddenByMid";
  //   });
  //   ASSERT_NE(E, I);
  //   EXPECT_EQ(sys::fs::owner_write, I->getPermissions());
  // }
}

// NOTE: in the tests below, we use '//root/' as our root directory, since it is
// a legal *absolute* path on Windows as well as *nix.
class VFSFromYAMLTest : public ::testing::Test {
public:
  int NumDiagnostics;

  void SetUp() {
    NumDiagnostics = 0;
  }

  static void CountingDiagHandler(const SMDiagnostic &, void *Context) {
    VFSFromYAMLTest *Test = static_cast<VFSFromYAMLTest *>(Context);
    ++Test->NumDiagnostics;
  }

  IntrusiveRefCntPtr<vfs::FileSystem>
  getFromYAMLRawString(StringRef Content,
                       IntrusiveRefCntPtr<vfs::FileSystem> ExternalFS) {
    MemoryBuffer *Buffer = MemoryBuffer::getMemBuffer(Content);
    return getVFSFromYAML(Buffer, CountingDiagHandler, this, ExternalFS);
  }

  IntrusiveRefCntPtr<vfs::FileSystem> getFromYAMLString(
      StringRef Content,
      IntrusiveRefCntPtr<vfs::FileSystem> ExternalFS = new DummyFileSystem()) {
    std::string VersionPlusContent("{\n  'version':0,\n");
    VersionPlusContent += Content.slice(Content.find('{') + 1, StringRef::npos);
    return getFromYAMLRawString(VersionPlusContent, ExternalFS);
  }
};

TEST_F(VFSFromYAMLTest, BasicVFSFromYAML) {
  IntrusiveRefCntPtr<vfs::FileSystem> FS;
  FS = getFromYAMLString("");
  EXPECT_EQ(nullptr, FS.getPtr());
  FS = getFromYAMLString("[]");
  EXPECT_EQ(nullptr, FS.getPtr());
  FS = getFromYAMLString("'string'");
  EXPECT_EQ(nullptr, FS.getPtr());
  EXPECT_EQ(3, NumDiagnostics);
}

TEST_F(VFSFromYAMLTest, MappedFiles) {
  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
  Lower->addRegularFile("//root/foo/bar/a");
  IntrusiveRefCntPtr<vfs::FileSystem> FS =
      getFromYAMLString("{ 'roots': [\n"
                        "{\n"
                        "  'type': 'directory',\n"
                        "  'name': '//root/',\n"
                        "  'contents': [ {\n"
                        "                  'type': 'file',\n"
                        "                  'name': 'file1',\n"
                        "                  'external-contents': '//root/foo/bar/a'\n"
                        "                },\n"
                        "                {\n"
                        "                  'type': 'file',\n"
                        "                  'name': 'file2',\n"
                        "                  'external-contents': '//root/foo/b'\n"
                        "                }\n"
                        "              ]\n"
                        "}\n"
                        "]\n"
                        "}",
                        Lower);
  ASSERT_TRUE(FS.getPtr() != nullptr);

  IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
      new vfs::OverlayFileSystem(Lower));
  O->pushOverlay(FS);

  // file
  ErrorOr<vfs::Status> S = O->status("//root/file1");
  ASSERT_FALSE(S.getError());
  EXPECT_EQ("//root/foo/bar/a", S->getName());

  ErrorOr<vfs::Status> SLower = O->status("//root/foo/bar/a");
  EXPECT_EQ("//root/foo/bar/a", SLower->getName());
  EXPECT_TRUE(S->equivalent(*SLower));

  // directory
  S = O->status("//root/");
  ASSERT_FALSE(S.getError());
  EXPECT_TRUE(S->isDirectory());
  EXPECT_TRUE(S->equivalent(*O->status("//root/"))); // non-volatile UniqueID

  // broken mapping
  EXPECT_EQ(O->status("//root/file2").getError(),
            llvm::errc::no_such_file_or_directory);
  EXPECT_EQ(0, NumDiagnostics);
}

TEST_F(VFSFromYAMLTest, CaseInsensitive) {
  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
  Lower->addRegularFile("//root/foo/bar/a");
  IntrusiveRefCntPtr<vfs::FileSystem> FS =
      getFromYAMLString("{ 'case-sensitive': 'false',\n"
                        "  'roots': [\n"
                        "{\n"
                        "  'type': 'directory',\n"
                        "  'name': '//root/',\n"
                        "  'contents': [ {\n"
                        "                  'type': 'file',\n"
                        "                  'name': 'XX',\n"
                        "                  'external-contents': '//root/foo/bar/a'\n"
                        "                }\n"
                        "              ]\n"
                        "}]}",
                        Lower);
  ASSERT_TRUE(FS.getPtr() != nullptr);

  IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
      new vfs::OverlayFileSystem(Lower));
  O->pushOverlay(FS);

  ErrorOr<vfs::Status> S = O->status("//root/XX");
  ASSERT_FALSE(S.getError());

  ErrorOr<vfs::Status> SS = O->status("//root/xx");
  ASSERT_FALSE(SS.getError());
  EXPECT_TRUE(S->equivalent(*SS));
  SS = O->status("//root/xX");
  EXPECT_TRUE(S->equivalent(*SS));
  SS = O->status("//root/Xx");
  EXPECT_TRUE(S->equivalent(*SS));
  EXPECT_EQ(0, NumDiagnostics);
}

TEST_F(VFSFromYAMLTest, CaseSensitive) {
  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
  Lower->addRegularFile("//root/foo/bar/a");
  IntrusiveRefCntPtr<vfs::FileSystem> FS =
      getFromYAMLString("{ 'case-sensitive': 'true',\n"
                        "  'roots': [\n"
                        "{\n"
                        "  'type': 'directory',\n"
                        "  'name': '//root/',\n"
                        "  'contents': [ {\n"
                        "                  'type': 'file',\n"
                        "                  'name': 'XX',\n"
                        "                  'external-contents': '//root/foo/bar/a'\n"
                        "                }\n"
                        "              ]\n"
                        "}]}",
                        Lower);
  ASSERT_TRUE(FS.getPtr() != nullptr);

  IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
      new vfs::OverlayFileSystem(Lower));
  O->pushOverlay(FS);

  ErrorOr<vfs::Status> SS = O->status("//root/xx");
  EXPECT_EQ(SS.getError(), llvm::errc::no_such_file_or_directory);
  SS = O->status("//root/xX");
  EXPECT_EQ(SS.getError(), llvm::errc::no_such_file_or_directory);
  SS = O->status("//root/Xx");
  EXPECT_EQ(SS.getError(), llvm::errc::no_such_file_or_directory);
  EXPECT_EQ(0, NumDiagnostics);
}

TEST_F(VFSFromYAMLTest, IllegalVFSFile) {
  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());

  // invalid YAML at top-level
  IntrusiveRefCntPtr<vfs::FileSystem> FS = getFromYAMLString("{]", Lower);
  EXPECT_EQ(nullptr, FS.getPtr());
  // invalid YAML in roots
  FS = getFromYAMLString("{ 'roots':[}", Lower);
  // invalid YAML in directory
  FS = getFromYAMLString(
      "{ 'roots':[ { 'name': 'foo', 'type': 'directory', 'contents': [}",
      Lower);
  EXPECT_EQ(nullptr, FS.getPtr());

  // invalid configuration
  FS = getFromYAMLString("{ 'knobular': 'true', 'roots':[] }", Lower);
  EXPECT_EQ(nullptr, FS.getPtr());
  FS = getFromYAMLString("{ 'case-sensitive': 'maybe', 'roots':[] }", Lower);
  EXPECT_EQ(nullptr, FS.getPtr());

  // invalid roots
  FS = getFromYAMLString("{ 'roots':'' }", Lower);
  EXPECT_EQ(nullptr, FS.getPtr());
  FS = getFromYAMLString("{ 'roots':{} }", Lower);
  EXPECT_EQ(nullptr, FS.getPtr());

  // invalid entries
  FS = getFromYAMLString(
      "{ 'roots':[ { 'type': 'other', 'name': 'me', 'contents': '' }", Lower);
  EXPECT_EQ(nullptr, FS.getPtr());
  FS = getFromYAMLString("{ 'roots':[ { 'type': 'file', 'name': [], "
                         "'external-contents': 'other' }",
                         Lower);
  EXPECT_EQ(nullptr, FS.getPtr());
  FS = getFromYAMLString(
      "{ 'roots':[ { 'type': 'file', 'name': 'me', 'external-contents': [] }",
      Lower);
  EXPECT_EQ(nullptr, FS.getPtr());
  FS = getFromYAMLString(
      "{ 'roots':[ { 'type': 'file', 'name': 'me', 'external-contents': {} }",
      Lower);
  EXPECT_EQ(nullptr, FS.getPtr());
  FS = getFromYAMLString(
      "{ 'roots':[ { 'type': 'directory', 'name': 'me', 'contents': {} }",
      Lower);
  EXPECT_EQ(nullptr, FS.getPtr());
  FS = getFromYAMLString(
      "{ 'roots':[ { 'type': 'directory', 'name': 'me', 'contents': '' }",
      Lower);
  EXPECT_EQ(nullptr, FS.getPtr());
  FS = getFromYAMLString(
      "{ 'roots':[ { 'thingy': 'directory', 'name': 'me', 'contents': [] }",
      Lower);
  EXPECT_EQ(nullptr, FS.getPtr());

  // missing mandatory fields
  FS = getFromYAMLString("{ 'roots':[ { 'type': 'file', 'name': 'me' }", Lower);
  EXPECT_EQ(nullptr, FS.getPtr());
  FS = getFromYAMLString(
      "{ 'roots':[ { 'type': 'file', 'external-contents': 'other' }", Lower);
  EXPECT_EQ(nullptr, FS.getPtr());
  FS = getFromYAMLString("{ 'roots':[ { 'name': 'me', 'contents': [] }", Lower);
  EXPECT_EQ(nullptr, FS.getPtr());

  // duplicate keys
  FS = getFromYAMLString("{ 'roots':[], 'roots':[] }", Lower);
  EXPECT_EQ(nullptr, FS.getPtr());
  FS = getFromYAMLString(
      "{ 'case-sensitive':'true', 'case-sensitive':'true', 'roots':[] }",
      Lower);
  EXPECT_EQ(nullptr, FS.getPtr());
  FS =
      getFromYAMLString("{ 'roots':[{'name':'me', 'name':'you', 'type':'file', "
                        "'external-contents':'blah' } ] }",
                        Lower);
  EXPECT_EQ(nullptr, FS.getPtr());

  // missing version
  FS = getFromYAMLRawString("{ 'roots':[] }", Lower);
  EXPECT_EQ(nullptr, FS.getPtr());

  // bad version number
  FS = getFromYAMLRawString("{ 'version':'foo', 'roots':[] }", Lower);
  EXPECT_EQ(nullptr, FS.getPtr());
  FS = getFromYAMLRawString("{ 'version':-1, 'roots':[] }", Lower);
  EXPECT_EQ(nullptr, FS.getPtr());
  FS = getFromYAMLRawString("{ 'version':100000, 'roots':[] }", Lower);
  EXPECT_EQ(nullptr, FS.getPtr());
  EXPECT_EQ(24, NumDiagnostics);
}

TEST_F(VFSFromYAMLTest, UseExternalName) {
  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
  Lower->addRegularFile("//root/external/file");

  IntrusiveRefCntPtr<vfs::FileSystem> FS = getFromYAMLString(
      "{ 'roots': [\n"
      "  { 'type': 'file', 'name': '//root/A',\n"
      "    'external-contents': '//root/external/file'\n"
      "  },\n"
      "  { 'type': 'file', 'name': '//root/B',\n"
      "    'use-external-name': true,\n"
      "    'external-contents': '//root/external/file'\n"
      "  },\n"
      "  { 'type': 'file', 'name': '//root/C',\n"
      "    'use-external-name': false,\n"
      "    'external-contents': '//root/external/file'\n"
      "  }\n"
      "] }", Lower);
  ASSERT_TRUE(nullptr != FS.getPtr());

  // default true
  EXPECT_EQ("//root/external/file", FS->status("//root/A")->getName());
  // explicit
  EXPECT_EQ("//root/external/file", FS->status("//root/B")->getName());
  EXPECT_EQ("//root/C", FS->status("//root/C")->getName());

  // global configuration
  FS = getFromYAMLString(
      "{ 'use-external-names': false,\n"
      "  'roots': [\n"
      "  { 'type': 'file', 'name': '//root/A',\n"
      "    'external-contents': '//root/external/file'\n"
      "  },\n"
      "  { 'type': 'file', 'name': '//root/B',\n"
      "    'use-external-name': true,\n"
      "    'external-contents': '//root/external/file'\n"
      "  },\n"
      "  { 'type': 'file', 'name': '//root/C',\n"
      "    'use-external-name': false,\n"
      "    'external-contents': '//root/external/file'\n"
      "  }\n"
      "] }", Lower);
  ASSERT_TRUE(nullptr != FS.getPtr());

  // default
  EXPECT_EQ("//root/A", FS->status("//root/A")->getName());
  // explicit
  EXPECT_EQ("//root/external/file", FS->status("//root/B")->getName());
  EXPECT_EQ("//root/C", FS->status("//root/C")->getName());
}

TEST_F(VFSFromYAMLTest, MultiComponentPath) {
  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
  Lower->addRegularFile("//root/other");

  // file in roots
  IntrusiveRefCntPtr<vfs::FileSystem> FS = getFromYAMLString(
      "{ 'roots': [\n"
      "  { 'type': 'file', 'name': '//root/path/to/file',\n"
      "    'external-contents': '//root/other' }]\n"
      "}", Lower);
  ASSERT_TRUE(nullptr != FS.getPtr());
  EXPECT_FALSE(FS->status("//root/path/to/file").getError());
  EXPECT_FALSE(FS->status("//root/path/to").getError());
  EXPECT_FALSE(FS->status("//root/path").getError());
  EXPECT_FALSE(FS->status("//root/").getError());

  // at the start
  FS = getFromYAMLString(
      "{ 'roots': [\n"
      "  { 'type': 'directory', 'name': '//root/path/to',\n"
      "    'contents': [ { 'type': 'file', 'name': 'file',\n"
      "                    'external-contents': '//root/other' }]}]\n"
      "}", Lower);
  ASSERT_TRUE(nullptr != FS.getPtr());
  EXPECT_FALSE(FS->status("//root/path/to/file").getError());
  EXPECT_FALSE(FS->status("//root/path/to").getError());
  EXPECT_FALSE(FS->status("//root/path").getError());
  EXPECT_FALSE(FS->status("//root/").getError());

  // at the end
  FS = getFromYAMLString(
      "{ 'roots': [\n"
      "  { 'type': 'directory', 'name': '//root/',\n"
      "    'contents': [ { 'type': 'file', 'name': 'path/to/file',\n"
      "                    'external-contents': '//root/other' }]}]\n"
      "}", Lower);
  ASSERT_TRUE(nullptr != FS.getPtr());
  EXPECT_FALSE(FS->status("//root/path/to/file").getError());
  EXPECT_FALSE(FS->status("//root/path/to").getError());
  EXPECT_FALSE(FS->status("//root/path").getError());
  EXPECT_FALSE(FS->status("//root/").getError());
}

TEST_F(VFSFromYAMLTest, TrailingSlashes) {
  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
  Lower->addRegularFile("//root/other");

  // file in roots
  IntrusiveRefCntPtr<vfs::FileSystem> FS = getFromYAMLString(
      "{ 'roots': [\n"
      "  { 'type': 'directory', 'name': '//root/path/to////',\n"
      "    'contents': [ { 'type': 'file', 'name': 'file',\n"
      "                    'external-contents': '//root/other' }]}]\n"
      "}", Lower);
  ASSERT_TRUE(nullptr != FS.getPtr());
  EXPECT_FALSE(FS->status("//root/path/to/file").getError());
  EXPECT_FALSE(FS->status("//root/path/to").getError());
  EXPECT_FALSE(FS->status("//root/path").getError());
  EXPECT_FALSE(FS->status("//root/").getError());
}

TEST_F(VFSFromYAMLTest, DirectoryIteration) {
  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
  Lower->addDirectory("//root/");
  Lower->addDirectory("//root/foo");
  Lower->addDirectory("//root/foo/bar");
  Lower->addRegularFile("//root/foo/bar/a");
  Lower->addRegularFile("//root/foo/bar/b");
  Lower->addRegularFile("//root/file3");
  IntrusiveRefCntPtr<vfs::FileSystem> FS =
  getFromYAMLString("{ 'use-external-names': false,\n"
                    "  'roots': [\n"
                    "{\n"
                    "  'type': 'directory',\n"
                    "  'name': '//root/',\n"
                    "  'contents': [ {\n"
                    "                  'type': 'file',\n"
                    "                  'name': 'file1',\n"
                    "                  'external-contents': '//root/foo/bar/a'\n"
                    "                },\n"
                    "                {\n"
                    "                  'type': 'file',\n"
                    "                  'name': 'file2',\n"
                    "                  'external-contents': '//root/foo/bar/b'\n"
                    "                }\n"
                    "              ]\n"
                    "}\n"
                    "]\n"
                    "}",
                    Lower);
  ASSERT_TRUE(FS.getPtr() != NULL);

  IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
      new vfs::OverlayFileSystem(Lower));
  O->pushOverlay(FS);

  std::error_code EC;
  {
    std::vector<std::string> Contents = { "//root/file1", "//root/file2",
        "//root/file3", "//root/foo" };
    checkContents(O->dir_begin("//root/", EC), Contents);
  }

  {
    std::vector<std::string> Contents = {
        "//root/foo/bar/a", "//root/foo/bar/b" };
    checkContents(O->dir_begin("//root/foo/bar", EC), Contents);
  }
}