tests: Add test case for std::ios_base::ate

Author: ken2812221

src/Makefile.test.include

@@ -51,6 +51,7 @@ BITCOIN_TESTS =\
   test/cuckoocache_tests.cpp \
   test/denialofservice_tests.cpp \
   test/descriptor_tests.cpp \
+  test/fs_tests.cpp \
   test/getarg_tests.cpp \
   test/hash_tests.cpp \
   test/key_io_tests.cpp \

src/test/fs_tests.cpp

@@ -0,0 +1,56 @@
+// Copyright (c) 2011-2018 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+//
+#include <fs.h>
+#include <test/test_bitcoin.h>
+
+#include <boost/test/unit_test.hpp>
+
+BOOST_FIXTURE_TEST_SUITE(fs_tests, BasicTestingSetup)
+
+BOOST_AUTO_TEST_CASE(fsbridge_fstream)
+{
+    fs::path tmpfolder = SetDataDir("fsbridge_fstream");
+    // tmpfile1 should be the same as tmpfile2
+    fs::path tmpfile1 = tmpfolder / "fs_tests_₿_🏃";
+    fs::path tmpfile2 = tmpfolder / L"fs_tests_₿_🏃";
+    {
+        fsbridge::ofstream file(tmpfile1);
+        file << "bitcoin";
+    }
+    {
+        fsbridge::ifstream file(tmpfile2);
+        std::string input_buffer;
+        file >> input_buffer;
+        BOOST_CHECK_EQUAL(input_buffer, "bitcoin");
+    }
+    {
+        fsbridge::ifstream file(tmpfile1, std::ios_base::in | std::ios_base::ate);
+        std::string input_buffer;
+        file >> input_buffer;
+        BOOST_CHECK_EQUAL(input_buffer, "");
+    }
+    {
+        fsbridge::ofstream file(tmpfile2, std::ios_base::out | std::ios_base::app);
+        file << "tests";
+    }
+    {
+        fsbridge::ifstream file(tmpfile1);
+        std::string input_buffer;
+        file >> input_buffer;
+        BOOST_CHECK_EQUAL(input_buffer, "bitcointests");
+    }
+    {
+        fsbridge::ofstream file(tmpfile2, std::ios_base::out | std::ios_base::trunc);
+        file << "bitcoin";
+    }
+    {
+        fsbridge::ifstream file(tmpfile1);
+        std::string input_buffer;
+        file >> input_buffer;
+        BOOST_CHECK_EQUAL(input_buffer, "bitcoin");
+    }
+}
+
+BOOST_AUTO_TEST_SUITE_END()