Merge pull request #1392 from bhangart/fix/grid-size-guard

Never use a folio grid step below 1 from the settings

tests/qttest/CMakeLists.txt

@@ -135,6 +135,13 @@ add_test(NAME tst_textgrid COMMAND tst_textgrid)
 target_include_directories(tst_textgrid PRIVATE ${QET_DIR}/sources)
 target_link_libraries(tst_textgrid PRIVATE Qt::Test)
 
+# foliogrid.h is header-only: the folio grid step as read from the
+# settings, never 0 or negative, so no reader can divide by it or loop on it.
+add_executable(tst_foliogrid tst_foliogrid.cpp)
+target_include_directories(tst_foliogrid PRIVATE ${QET_DIR}/sources)
+target_link_libraries(tst_foliogrid PRIVATE Qt::Test Qt::Core)
+add_test(NAME tst_foliogrid COMMAND tst_foliogrid)
+
 # textlines.h is header-only: the lines of a text as they are laid out,
 # for the exports that write a text line by line.
 add_executable(tst_textlines tst_textlines.cpp)

tests/qttest/tst_foliogrid.cpp

@@ -0,0 +1,99 @@
+/*
+	Copyright 2006-2026 The QElectroTech Team
+	This file is part of QElectroTech.
+
+	QElectroTech 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.
+
+	QElectroTech 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 QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#include "foliogrid.h"
+
+#include <QtTest>
+#include <QSettings>
+
+/**
+	FolioGrid::step() -- the folio grid step as read from the settings.
+	Every reader of diagrameditor/Xgrid and Ygrid goes through it, so a
+	settings file holding 0 (a division by zero in Diagram::snapToGrid()
+	and an endless "% 0" in drawBackground()), a negative number (an
+	endless loop) or text can no longer reach the code that uses the step.
+*/
+class tst_foliogrid : public QObject
+{
+	Q_OBJECT
+
+private slots:
+	void usableValuesAreKept_data()
+	{
+		QTest::addColumn<QVariant>("value");
+		QTest::addColumn<int>("expected");
+		QTest::newRow("one")          << QVariant(1) << 1;
+		QTest::newRow("default")      << QVariant(10) << 10;
+		QTest::newRow("text number")  << QVariant(QStringLiteral("7")) << 7;
+		QTest::newRow("large")        << QVariant(100000) << 100000;
+		QTest::newRow("int max")      << QVariant(2147483647) << 2147483647;
+	}
+
+	void usableValuesAreKept()
+	{
+		QFETCH(QVariant, value);
+		QFETCH(int, expected);
+		QCOMPARE(FolioGrid::step(value, 10), expected);
+	}
+
+	void unusableValuesFallBack_data()
+	{
+		QTest::addColumn<QVariant>("value");
+		QTest::newRow("missing")   << QVariant();
+		QTest::newRow("zero")      << QVariant(0);
+		QTest::newRow("negative")  << QVariant(-5);
+		QTest::newRow("text")      << QVariant(QStringLiteral("ten"));
+		QTest::newRow("empty")     << QVariant(QString());
+		QTest::newRow("nan")       << QVariant(QStringLiteral("nan"));
+		QTest::newRow("too large") << QVariant(QStringLiteral("99999999999"));
+		QTest::newRow("too large number") << QVariant(qlonglong(99999999999));
+		QTest::newRow("int max + 1") << QVariant(qlonglong(2147483648));
+	}
+
+	void unusableValuesFallBack()
+	{
+		QFETCH(QVariant, value);
+		QCOMPARE(FolioGrid::step(value, 10), 10);
+		QCOMPARE(FolioGrid::step(value, 20), 20);
+	}
+
+	// A decimal in the file is rounded to a whole number, as the plain
+	// QVariant::toInt() read did before.
+	void decimalIsRoundedLikeBefore()
+	{
+		QCOMPARE(FolioGrid::step(QVariant(7.9), 10), 8);
+		QCOMPARE(FolioGrid::step(QVariant(0.4), 10), 10);
+	}
+
+	// Through a real settings file, in a scope of this test's own.
+	void readsTheSettingsKeys()
+	{
+		QCoreApplication::setOrganizationName(QStringLiteral("QElectroTech-tst_foliogrid"));
+		QCoreApplication::setApplicationName(QStringLiteral("tst_foliogrid"));
+		QSettings settings;
+		settings.clear();
+		QCOMPARE(FolioGrid::step(settings.value(FolioGrid::x_key), 10), 10);
+		settings.setValue(FolioGrid::x_key, 0);
+		settings.setValue(FolioGrid::y_key, 15);
+		QCOMPARE(FolioGrid::step(settings.value(FolioGrid::x_key), 10), 10);
+		QCOMPARE(FolioGrid::step(settings.value(FolioGrid::y_key), 10), 15);
+		settings.clear();
+	}
+};
+
+QTEST_GUILESS_MAIN(tst_foliogrid)
+#include "tst_foliogrid.moc"