IncrementalReader: Test reading from files

2 files changed, 143 insertions, 1 deletions

diff --git a/test/utils/cpp/TARGETS b/test/utils/cpp/TARGETS
index 9a809b47..c7ef6b21 100644
--- a/test/utils/cpp/TARGETS
+++ b/test/utils/cpp/TARGETS
@@ -45,9 +45,26 @@
     ]
   , "stage": ["test", "utils", "cpp"]
   }
+, "incremental_reader":
+  { "type": ["@", "rules", "CC/test", "test"]
+  , "name": ["incremental_reader"]
+  , "srcs": ["incremental_reader.test.cpp"]
+  , "private-deps":
+    [ ["@", "catch2", "", "catch2"]
+    , ["@", "src", "src/buildtool/storage", "config"]
+    , ["@", "src", "src/utils/cpp", "expected"]
+    , ["@", "src", "src/utils/cpp", "incremental_reader"]
+    , ["@", "src", "src/utils/cpp", "tmp_dir"]
+    , ["", "catch-main"]
+    , ["utils", "large_object_utils"]
+    , ["utils", "test_storage_config"]
+    ]
+  , "stage": ["test", "utils", "cpp"]
+  }
 , "TESTS":
   { "type": ["@", "rules", "test", "suite"]
   , "stage": ["cpp"]
-  , "deps": ["file_locking", "path", "path_rebase", "prefix"]
+  , "deps":
+    ["file_locking", "incremental_reader", "path", "path_rebase", "prefix"]
   }
 }
diff --git a/test/utils/cpp/incremental_reader.test.cpp b/test/utils/cpp/incremental_reader.test.cpp
new file mode 100644
index 00000000..4f362351
--- /dev/null
+++ b/test/utils/cpp/incremental_reader.test.cpp
@@ -0,0 +1,125 @@
+// Copyright 2025 Huawei Cloud Computing Technology Co., Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "src/utils/cpp/incremental_reader.hpp"
+
+#include <cstddef>
+#include <cstdint>
+#include <filesystem>
+#include <fstream>
+#include <memory>
+#include <optional>
+#include <string>
+#include <string_view>
+
+#include "catch2/catch_test_macros.hpp"
+#include "src/buildtool/storage/config.hpp"
+#include "src/utils/cpp/expected.hpp"
+#include "src/utils/cpp/tmp_dir.hpp"
+#include "test/utils/hermeticity/test_storage_config.hpp"
+#include "test/utils/large_objects/large_object_utils.hpp"
+
+[[nodiscard]] static auto ReadFile(std::filesystem::path const& path) noexcept
+    -> std::optional<std::string> {
+    try {
+        std::size_t const file_size = std::filesystem::file_size(path);
+        std::string result(file_size, '\0');
+
+        std::ifstream istream(path.string(), std::ios_base::binary);
+        if (not istream.good()) {
+            return std::nullopt;
+        }
+        istream.read(result.data(), static_cast<std::streamsize>(file_size));
+        return result;
+    } catch (...) {
+        return std::nullopt;
+    }
+}
+
+TEST_CASE("IncrementalReader", "[incremental_reader]") {
+    static constexpr auto kFileSize =
+        static_cast<std::uintmax_t>(5 * 1024 * 1024);
+
+    static constexpr std::size_t kChunkWithRemainder = 107;
+    static_assert(kFileSize % kChunkWithRemainder != 0);
+
+    static constexpr std::size_t kChunkWithoutRemainder = 128;
+    static_assert(kFileSize % kChunkWithoutRemainder == 0);
+
+    auto const config = TestStorageConfig::Create();
+
+    auto temp_dir = config.Get().CreateTypedTmpDir("incremental_reader");
+    REQUIRE(temp_dir);
+
+    auto const file_path = temp_dir->GetPath() / "file";
+    REQUIRE(LargeObjectUtils::GenerateFile(file_path, kFileSize));
+
+    auto const file_content = ::ReadFile(file_path);
+    REQUIRE(file_content.has_value());
+
+    SECTION("File") {
+        auto reader =
+            IncrementalReader::FromFile(kChunkWithRemainder, file_path);
+        REQUIRE(reader.has_value());
+
+        std::string result;
+        result.reserve(reader->GetContentSize());
+        for (auto chunk : *reader) {
+            REQUIRE(chunk.has_value());
+            result.append(*chunk);
+        }
+        REQUIRE(result.size() == file_content->size());
+        REQUIRE(result == *file_content);
+
+        reader = IncrementalReader::FromFile(kChunkWithoutRemainder, file_path);
+        REQUIRE(reader.has_value());
+
+        result.clear();
+        for (auto chunk : *reader) {
+            REQUIRE(chunk.has_value());
+            result.append(*chunk);
+        }
+        REQUIRE(result.size() == file_content->size());
+        REQUIRE(result == *file_content);
+    }
+}
+
+TEST_CASE("IncrementalReader - Empty", "[incremental_reader]") {
+    static constexpr std::size_t kChunkSize = 128;
+    SECTION("File") {
+        auto const config = TestStorageConfig::Create();
+
+        auto temp_dir = config.Get().CreateTypedTmpDir("incremental_reader");
+        REQUIRE(temp_dir);
+
+        std::filesystem::path const empty_file = temp_dir->GetPath() / "file";
+        {
+            std::ofstream stream(empty_file);
+            stream << "";
+        }
+        auto const reader = IncrementalReader::FromFile(kChunkSize, empty_file);
+        REQUIRE(reader.has_value());
+
+        std::optional<std::string> result;
+        for (auto chunk : *reader) {
+            REQUIRE(chunk.has_value());
+            if (not result.has_value()) {
+                result = std::string{};
+            }
+            result->append(*chunk);
+        }
+        REQUIRE(result.has_value());
+        REQUIRE(result->empty());
+    }
+}