GH-1227 add GZip compress function and a unit test fo GZip

tests/CMakeLists.txt

@@ -31,6 +31,7 @@ add_unit_test(UpdateChecker tst_UpdateChecker.cpp)
 add_unit_test(DownloadTask tst_DownloadTask.cpp)
 add_unit_test(filematchers tst_filematchers.cpp)
 add_unit_test(Resource tst_Resource.cpp)
+add_unit_test(GZip tst_GZip.cpp)
 
 # Tests END #
 

tests/tst_GZip.cpp

@@ -0,0 +1,55 @@
+#include <QTest>
+#include "TestUtil.h"
+
+#include "GZip.h"
+#include <random>
+
+void fib(int &prev, int &cur)
+{
+	auto ret = prev + cur;
+	prev = cur;
+	cur = ret;
+}
+
+class GZipTest : public QObject
+{
+	Q_OBJECT
+private
+slots:
+
+	void test_Through()
+	{
+		// test up to 10 MB
+		static const int size = 10 * 1024 * 1024;
+		QByteArray random;
+		QByteArray compressed;
+		QByteArray decompressed;
+		std::default_random_engine eng((std::random_device())());
+		std::uniform_int_distribution<uint8_t> idis(0, std::numeric_limits<uint8_t>::max());
+
+		// initialize random buffer
+		for(int i = 0; i < size; i++)
+		{
+			random.append((char)idis(eng));
+		}
+
+		// initialize fibonacci
+		int prev = 1;
+		int cur = 1;
+
+		// test if fibonacci long random buffers pass through GZip
+		do
+		{
+			QByteArray copy = random;
+			copy.resize(cur);
+			QVERIFY(GZip::compress(copy, compressed));
+			QVERIFY(GZip::decompress(compressed, decompressed));
+			QCOMPARE(decompressed, copy);
+			fib(prev, cur);
+		} while (cur < size);
+	}
+};
+
+QTEST_GUILESS_MAIN(GZipTest)
+
+#include "tst_GZip.moc"