Add support for unit testing

* Downgraded macOS CI to Qt 6.2.0 due to a bug in Qt Test module
* Revised cmake build scripts
* For now, only building via cmake is supported

PR #17338.

test/CMakeLists.txt

@@ -0,0 +1,19 @@
+if (QT6)
+    find_package(Qt6 REQUIRED COMPONENTS Test)
+else()
+    find_package(Qt5 REQUIRED COMPONENTS Test)
+endif()
+
+enable_testing(true)
+add_custom_target(check COMMAND ${CMAKE_CTEST_COMMAND} --output-on-failure)
+
+include_directories("../src")
+
+file(GLOB testFiles "${CMAKE_CURRENT_SOURCE_DIR}/test*.cpp")
+foreach(testFile ${testFiles})
+    get_filename_component(testFilename "${testFile}" NAME_WLE)
+
+    add_executable("${testFilename}" "${testFile}")
+    target_link_libraries("${testFilename}" PRIVATE Qt::Test qbt_base)
+    add_test(NAME "${testFilename}" COMMAND "${testFilename}")
+endforeach()

test/Readme.md

@@ -0,0 +1,4 @@
+# Test suite
+
+To run tests, add `-DTESTING=ON` argument when invoking cmake, then build the app as usual. \
+After building, run `cmake --build <build> --target check` where `<build>` is your cmake build directory.

test/testutilsgzip.cpp

@@ -0,0 +1,70 @@
+/*
+ * Bittorrent Client using Qt and libtorrent.
+ * Copyright (C) 2022  Mike Tzou (Chocobo1)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ * In addition, as a special exception, the copyright holders give permission to
+ * link this program with the OpenSSL project's "OpenSSL" library (or with
+ * modified versions of it that use the same license as the "OpenSSL" library),
+ * and distribute the linked executables. You must obey the GNU General Public
+ * License in all respects for all of the code used other than "OpenSSL".  If you
+ * modify file(s), you may extend this exception to your version of the file(s),
+ * but you are not obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ */
+
+#include <QTest>
+
+#include "base/global.h"
+#include "base/utils/gzip.h"
+
+class TestUtilsGzip final : public QObject
+{
+    Q_OBJECT
+    Q_DISABLE_COPY_MOVE(TestUtilsGzip)
+
+public:
+    TestUtilsGzip() = default;
+
+private slots:
+    void testCompress() const
+    {
+        // compressed data is not reproducible, see: https://stackoverflow.com/questions/30150972/are-there-test-vectors-available-for-gzip
+        const QByteArray data = QByteArrayLiteral("abc");
+
+        bool ok = false;
+        const QByteArray compressedData = Utils::Gzip::compress(data, 6, &ok);
+        QVERIFY(ok);
+    }
+
+    void testDecompress() const
+    {
+        const QByteArray data = QByteArrayLiteral("abc");
+
+        bool ok = false;
+        const QByteArray compressedData = Utils::Gzip::compress(data, 6, &ok);
+        QVERIFY(ok);
+        QVERIFY(compressedData != data);
+
+        ok = false;
+        const QByteArray decompressedData = Utils::Gzip::decompress(compressedData, &ok);
+        QVERIFY(ok);
+        QCOMPARE(decompressedData, data);
+    }
+};
+
+QTEST_APPLESS_MAIN(TestUtilsGzip)
+#include "testutilsgzip.moc"