1 files changed, 147 insertions, 0 deletions
diff --git a/llvm/unittests/Support/VirtualOutputBackendTest.cpp b/llvm/unittests/Support/VirtualOutputBackendTest.cpp
new file mode 100644
index 000000000000..3adb671d9777
--- /dev/null
+++ b/llvm/unittests/Support/VirtualOutputBackendTest.cpp
@@ -0,0 +1,147 @@
+//===- VirtualOutputBackendTest.cpp - Tests for vfs::OutputBackend --------===//
+//
+// 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 "llvm/Support/VirtualOutputBackend.h"
+#include "llvm/Testing/Support/Error.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+using namespace llvm::vfs;
+
+namespace {
+
+struct MockOutputBackendData {
+  int Cloned = 0;
+  int FilesCreated = 0;
+  std::optional<OutputConfig> LastConfig;
+  unique_function<Error()> FileCreator;
+};
+
+struct MockOutputBackend final : public OutputBackend {
+  struct MockFile final : public OutputFileImpl {
+    Error keep() override { return Error::success(); }
+    Error discard() override { return Error::success(); }
+    raw_pwrite_stream &getOS() override { return OS; }
+    raw_null_ostream OS;
+  };
+
+  IntrusiveRefCntPtr<OutputBackend> cloneImpl() const override {
+    ++Data.Cloned;
+    return const_cast<MockOutputBackend *>(this);
+  }
+
+  Expected<std::unique_ptr<OutputFileImpl>>
+  createFileImpl(StringRef, std::optional<OutputConfig> Config) override {
+    ++Data.FilesCreated;
+    Data.LastConfig = Config;
+    if (Data.FileCreator)
+      return Data.FileCreator();
+    return std::make_unique<MockFile>();
+  }
+
+  Expected<OutputFile>
+  createAutoDiscardFile(const Twine &OutputPath,
+                        std::optional<OutputConfig> Config = std::nullopt) {
+    return consumeDiscardOnDestroy(createFile(OutputPath, Config));
+  }
+
+  MockOutputBackend(MockOutputBackendData &Data) : Data(Data) {}
+  MockOutputBackendData &Data;
+};
+
+static IntrusiveRefCntPtr<MockOutputBackend>
+createMockBackend(MockOutputBackendData &Data) {
+  return makeIntrusiveRefCnt<MockOutputBackend>(Data);
+}
+
+static Error createCustomError() {
+  return createStringError(inconvertibleErrorCode(), "custom error");
+}
+
+TEST(VirtualOutputBackendTest, construct) {
+  MockOutputBackendData Data;
+  auto B = createMockBackend(Data);
+  EXPECT_EQ(0, Data.Cloned);
+  EXPECT_EQ(0, Data.FilesCreated);
+}
+
+TEST(VirtualOutputBackendTest, clone) {
+  MockOutputBackendData Data;
+  auto Backend = createMockBackend(Data);
+  auto Clone = Backend->clone();
+  EXPECT_EQ(1, Data.Cloned);
+
+  // Confirm the clone matches what the mock's cloneImpl() does.
+  EXPECT_EQ(Backend.get(), Clone.get());
+
+  // Make another clone.
+  Backend->clone();
+  EXPECT_EQ(2, Data.Cloned);
+}
+
+TEST(VirtualOutputBackendTest, createFile) {
+  MockOutputBackendData Data;
+  auto Backend = createMockBackend(Data);
+
+  StringRef FilePath = "dir/file";
+  OutputFile F;
+  EXPECT_THAT_ERROR(Backend->createFile(Twine(FilePath)).moveInto(F),
+                    Succeeded());
+  EXPECT_EQ(1, Data.FilesCreated);
+  EXPECT_EQ(FilePath, F.getPath());
+  EXPECT_EQ(std::nullopt, Data.LastConfig);
+
+  // Confirm OutputBackend has not installed a discard handler.
+#if GTEST_HAS_DEATH_TEST
+  EXPECT_DEATH(F = OutputFile(), "output not closed");
+#endif
+  consumeError(F.discard());
+
+  // Create more files and specify configs.
+  for (OutputConfig Config : {
+           OutputConfig(),
+           OutputConfig().setNoAtomicWrite().setDiscardOnSignal(),
+           OutputConfig().setAtomicWrite().setNoDiscardOnSignal(),
+           OutputConfig().setText(),
+           OutputConfig().setTextWithCRLF(),
+       }) {
+    int CreatedAlready = Data.FilesCreated;
+    EXPECT_THAT_ERROR(
+        Backend->createAutoDiscardFile(Twine(FilePath), Config).takeError(),
+        Succeeded());
+    EXPECT_EQ(Config, Data.LastConfig);
+    EXPECT_EQ(1 + CreatedAlready, Data.FilesCreated);
+  }
+}
+
+TEST(VirtualOutputBackendTest, createFileInvalidConfigCRLF) {
+  MockOutputBackendData Data;
+  auto Backend = createMockBackend(Data);
+
+  // Check that invalid configs don't make it to the backend.
+  EXPECT_THAT_ERROR(
+      Backend
+          ->createAutoDiscardFile(Twine("dir/file"), OutputConfig().setCRLF())
+          .takeError(),
+      FailedWithMessage("dir/file: invalid config: {CRLF}"));
+  EXPECT_EQ(0, Data.FilesCreated);
+}
+
+TEST(VirtualOutputBackendTest, createFileError) {
+  MockOutputBackendData Data;
+  Data.FileCreator = createCustomError;
+  auto Backend = createMockBackend(Data);
+
+  // Check that invalid configs don't make it to the backend.
+  EXPECT_THAT_ERROR(
+      Backend->createAutoDiscardFile(Twine("dir/file")).takeError(),
+      FailedWithMessage("custom error"));
+  EXPECT_EQ(1, Data.FilesCreated);
+}
+
+} // end namespace