From 2fee2fdff591c0ca44480b493d90b4c86f78a622 Mon Sep 17 00:00:00 2001
From: Robin Mueller <muellerr@irs.uni-stuttgart.de>
Date: Thu, 15 Sep 2022 16:20:52 +0200
Subject: [PATCH] unittest which would have caught this

---
 src/fsfw/filesystem/HasFileSystemIF.h |  4 ++--
 unittests/hal/testHostFilesystem.cpp  | 34 ++++++++++++++++++++++++---
 2 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/src/fsfw/filesystem/HasFileSystemIF.h b/src/fsfw/filesystem/HasFileSystemIF.h
index c86d12b9..6f7112ad 100644
--- a/src/fsfw/filesystem/HasFileSystemIF.h
+++ b/src/fsfw/filesystem/HasFileSystemIF.h
@@ -86,8 +86,8 @@ class HasFileSystemIF {
    * @brief   Generic function to write to a file.
    *
    * @details
-   * Implementations should not truncate the file. This is equivalent to opening a  file with "r+" on Unix systems
-   * or using ios::out | ios::in with the C++ API.
+   * Implementations should not truncate the file. This is equivalent to opening a  file with "r+"
+   * on Unix systems or using ios::out | ios::in with the C++ API.
    * @param fileOpInfo General information: File name, size to write, offset, additional arguments
    * @param data The data to write to the file
    */
diff --git a/unittests/hal/testHostFilesystem.cpp b/unittests/hal/testHostFilesystem.cpp
index 3873d5e9..e33b30cc 100644
--- a/unittests/hal/testHostFilesystem.cpp
+++ b/unittests/hal/testHostFilesystem.cpp
@@ -1,6 +1,9 @@
+#include <etl/crc32.h>
+
 #include <catch2/catch_test_macros.hpp>
 #include <filesystem>
 #include <fstream>
+#include <random>
 
 #include "fsfw/serialize/SerializeIF.h"
 #include "fsfw_hal/host/HostFilesystem.h"
@@ -70,12 +73,37 @@ TEST_CASE("Host Filesystem", "[hal][host]") {
           returnvalue::OK);
     CHECK(fs::file_size(file0) == data.size());
     ifstream ifile(file0);
-    char readBuf[524]{};
-    ifile.read(readBuf, sizeof(readBuf));
-    std::string readBackString(readBuf);
+    std::array<char, 524> readBuf{};
+    ifile.read(readBuf.data(), sizeof(readBuf));
+    std::string readBackString(readBuf.data());
     CHECK(data == readBackString);
   }
 
+  SECTION("Write To File, Check Not Truncated") {
+    std::random_device dev;
+    std::mt19937 rng(dev());
+    std::uniform_int_distribution<std::mt19937::result_type> distU8(1, 255);
+    std::array<uint8_t, 512> randData{};
+    for (uint8_t& byte : randData) {
+      byte = distU8(rng);
+    }
+    FileOpParams params(file0.c_str(), randData.size() - 256);
+    REQUIRE(hostFs.createFile(params.fsParams) == returnvalue::OK);
+    CHECK(fs::is_regular_file(file0));
+    REQUIRE(fs::exists(file0));
+    // Write first file chunk
+    CHECK(hostFs.writeToFile(params, randData.cbegin()) == returnvalue::OK);
+    params.offset = 256;
+    CHECK(hostFs.writeToFile(params, randData.cbegin() + 256) == returnvalue::OK);
+    std::ifstream rf(file0, ios::binary);
+    std::array<uint8_t, 512> readBack{};
+    REQUIRE(std::filesystem::file_size(file0) == 512);
+    rf.read(reinterpret_cast<char*>(readBack.data()), readBack.size());
+    for (size_t i = 0; i < 512; i++) {
+      CHECK(randData[i] == readBack[i]);
+    }
+  }
+
   SECTION("Read From File") {
     std::string data = "hello world!";
     FileOpParams params(file0.c_str(), data.size());