Add a test for to_utf8 component

components/to_utf8/tests/.gitignore

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+*_test

components/to_utf8/tests/output/to_utf8_test.out

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+original:  Без вопросов отдаете ему рулет, зная, что позже вы сможете привести с собой своих друзей и тогда он получит по заслугам?
+converted: Без вопросов отдаете ему рулет, зная, что позже вы сможете привести с собой своих друзей и тогда он получит по заслугам?
+original:  Vous lui donnez le gâteau sans protester avant d’aller chercher tous vos amis et de revenir vous venger.
+converted: Vous lui donnez le gâteau sans protester avant d’aller chercher tous vos amis et de revenir vous venger.

components/to_utf8/tests/test.sh

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+#!/bin/bash
+
+make || exit
+
+mkdir -p output
+
+PROGS=*_test
+
+for a in $PROGS; do
+    if [ -f "output/$a.out" ]; then
+        echo "Running $a:"
+        ./$a | diff output/$a.out -
+    else
+        echo "Creating $a.out"
+        ./$a > "output/$a.out"
+        git add "output/$a.out"
+    fi
+done

components/to_utf8/tests/to_utf8_test.cpp

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+#include <iostream>
+#include <fstream>
+#include <cassert>
+#include <stdexcept>
+#include <typeinfo>
+
+#include "../to_utf8.hpp"
+
+std::string getFirstLine(const std::string &filename);
+void testEncoder(ToUTF8::FromType encoding, const std::string &legacyEncFile,
+                 const std::string &utf8File);
+
+/// Test character encoding conversion to and from UTF-8
+void testEncoder(ToUTF8::FromType encoding, const std::string &legacyEncFile,
+                 const std::string &utf8File)
+{
+    // get some test data
+    std::string legacyEncLine = getFirstLine(legacyEncFile);
+    std::string utf8Line = getFirstLine(utf8File);
+
+    // create an encoder for specified character encoding
+    ToUTF8::Utf8Encoder encoder;
+    encoder.setEncoding(encoding);
+
+    // convert text to UTF-8
+    std::string convertedUtf8Line = encoder.getUtf8(legacyEncLine);
+
+    std::cout << "original:  " << utf8Line          << std::endl;
+    std::cout << "converted: " << convertedUtf8Line << std::endl;
+
+    // check correctness
+    assert(convertedUtf8Line == utf8Line);
+
+    // convert UTF-8 text to legacy encoding
+    std::string convertedLegacyEncLine = encoder.getLegacyEnc(utf8Line);
+    // check correctness
+    assert(convertedLegacyEncLine == legacyEncLine);
+}
+
+std::string getFirstLine(const std::string &filename)
+{
+    std::string line;
+    std::ifstream text (filename.c_str());
+
+    if (!text.is_open())
+    {
+        throw std::runtime_error("Unable to open file " + filename);
+    }
+
+    std::getline(text, line);
+    text.close();
+
+    return line;
+}
+
+int main()
+{
+    testEncoder(ToUTF8::WINDOWS_1251, "data/russian-win1251.txt", "data/russian-utf8.txt");
+    testEncoder(ToUTF8::WINDOWS_1252, "data/french-win1252.txt", "data/french-utf8.txt");
+    return 0;
+}