add few characterisation tests for exiv2::strError

unitTests/test_futils.cpp

@@ -0,0 +1,32 @@
+// File under test
+#include <exiv2/futils.hpp>
+
+// Auxiliary headers
+#include <fstream>
+#include <cstdio>
+#include <cerrno>
+
+#include <gtest/gtest.h>
+
+using namespace Exiv2;
+
+TEST(strError, returnSuccessAfterClosingFile)
+{
+    std::string tmpFile("tmp.dat");
+    std::ofstream auxFile(tmpFile.c_str());
+    auxFile.close();
+    ASSERT_STREQ("Success (errno = 0)", strError().c_str());
+    std::remove(tmpFile.c_str());
+}
+
+TEST(strError, returnNoSuchFileOrDirectoryWhenTryingToOpenNonExistingFile)
+{
+    std::ifstream auxFile("nonExistingFile");
+    ASSERT_STREQ("No such file or directory (errno = 2)", strError().c_str());
+}
+
+TEST(strError, doNotRecognizeUnknownError)
+{
+    errno = 9999;
+    ASSERT_STREQ("Unknown error 9999 (errno = 9999)", strError().c_str());
+}