tests: Tests now run 10x faster, with ctest -j10 or so

Introduced an indirection, tests_launcher, which can run a subset
of the 140 tests, this way it's paralelizable by ctest

tests/tests_launcher.cpp

@@ -0,0 +1,136 @@
+/*
+  This file is part of KDDockWidgets.
+
+  Copyright (C) 2020 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com
+  Author: Sérgio Martins <sergio.martins@kdab.com>
+
+  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, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <QCoreApplication>
+#include <QProcess>
+#include <QDebug>
+#include <qmath.h>
+
+/// @file
+/// @brief Indirection to run tst_docks.exe. tst_docks is very big (140 tests), so instead we invoke
+/// this launcher N times on a smaller subset, so we can use threads
+
+static QStringList availableTests()
+{
+    QProcess p;
+    p.setProgram(QString("%1/tst_docks").arg(qApp->applicationDirPath()));
+    p.setArguments({ "-datatags" });
+    p.start();
+    const bool started = p.waitForStarted();
+    if (!started) {
+        qWarning() << "Failed to start process" << p.program();
+        return {};
+    }
+
+    p.waitForFinished();
+
+    const QString output = p.readAllStandardOutput();
+    QStringList functions = output.split('\n');
+
+    QStringList result;
+
+    for (QString &function : functions) {
+        function = function.replace("()", "").trimmed();
+        function = function.replace(" ", ":"); // datatags
+        function = function.replace("KDDockWidgets::TestDocks:", "");
+        if (!function.isEmpty())
+            result << function;
+    }
+
+    return result;
+}
+
+static QStringList calculateSubset(int subsetNumber, int subsetPercentage, const QStringList &allFunctions)
+{
+    if (allFunctions.isEmpty()) {
+        qWarning() << Q_FUNC_INFO << "No tests to run";
+        return {};
+    }
+
+    const int blockSize = (subsetPercentage / 100.0) * allFunctions.size();
+    const int numBlocks = qCeil(allFunctions.size() / (blockSize * 1.0));
+
+    if (subsetNumber >= numBlocks)
+        return {};
+
+    QVector<QStringList> subsets;
+    subsets.resize(numBlocks);
+
+    int i = 0;
+    // Interleave, since the first tst_docks functions take more time, due to mouse dragging
+    for (const QString &func : allFunctions) {
+        QStringList &subset = subsets[i % numBlocks];
+        subset << func;
+        i++;
+    }
+
+    return subsets.at(subsetNumber);
+}
+
+static int run_tests(const QStringList &subset)
+{
+    if (subset.isEmpty())
+        return 0;
+
+    QProcess p;
+    p.setProgram(QString("%1/tst_docks").arg(qApp->applicationDirPath()));
+    p.setArguments(subset);
+    p.setProcessChannelMode(QProcess::ForwardedChannels);
+    p.start();
+    const bool started = p.waitForStarted();
+    if (!started) {
+        qWarning() << "Failed to start process" << p.program();
+        return {};
+    }
+
+    p.waitForFinished();
+
+    return p.exitCode();
+}
+
+int main(int argv, char**argc)
+{
+    QCoreApplication app(argv, argc);
+
+    if (app.arguments().size() != 3) {
+        qWarning() << "Usage:" << app.arguments().constFirst() << "<subsetNumber>" << "<subsetPercentage>";
+        return -1;
+    }
+
+    bool ok = false;
+    const int subsetNumber = app.arguments()[1].toInt(&ok);
+    if (!ok) {
+        qWarning() << "Invalid number" << app.arguments()[1];
+        return -1;
+    }
+
+    const int subsetPercentage = app.arguments()[2].toInt(&ok);
+    if (!ok) {
+        qWarning() << "Invalid number" << app.arguments()[2];
+        return -1;
+    }
+
+    if (subsetPercentage > 100 || subsetPercentage <= 0) {
+        qWarning() << "Invalid percentage" << app.arguments()[2];
+        return -1;
+    }
+
+    return run_tests(calculateSubset(subsetNumber, subsetPercentage, availableTests()));
+}