Test the second save on every example, a single-space value and accents

Review of #1109 (scorpio810):

- tst_resaveunchanged now resaves every .qet in examples/ twice instead
  of two of them (24 rows, ~40 s). Dropping the load-time trim now also
  fails affuteuse_250h.qet, which the two-file version missed.
- New case singleSpaceValueKept: a title-block property set to one
  space survives two saves (#973), and an accented property comes back
  unchanged. Fails if qetproject.cpp stops parsing with
  PreserveSpacingOnlyNodes.
- New tst_diagramcontext: the QDom reader (projects) and the pugixml
  reader (element definitions in the collection) return the same value
  for plain, stray-spaced, accented and non-Latin text. Fails if the
  pugixml path decodes as Latin-1 or either reader stops trimming.

The pugixml reader still reads a single-space value as "": pugixml drops
whitespace-only text unless parse_ws_pcdata is set, as it did before
this PR. That reader only sees element definitions, never a project, so
#973's title-block values do not go through it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/qttest/CMakeLists.txt

@@ -330,8 +330,8 @@ target_compile_definitions(tst_conductorselfretrace PRIVATE
   "QET_TEST_BINARY_PATH=\"$<TARGET_FILE:qelectrotech>\"")
 
 # Saving a project that was just saved changes nothing: runs the real
-# binary's --resave twice on examples/Projet_vierge.qet (empty information
-# values) and examples/m_000.qet (information values with stray spaces).
+# binary's --resave twice on every project in examples/, and on one whose
+# title block holds a single-space value (#973).
 add_executable(
   tst_resaveunchanged
   tst_resaveunchanged.cpp)
@@ -341,3 +341,17 @@ target_link_libraries(tst_resaveunchanged PRIVATE Qt::Test)
 target_compile_definitions(tst_resaveunchanged PRIVATE
   "QET_TEST_BINARY_PATH=\"$<TARGET_FILE:qelectrotech>\""
   "QET_EXAMPLES_DIR=\"${QET_DIR}/examples\"")
+
+# DiagramContext::fromXml() -- the two readers (QDom for projects, pugixml
+# for element definitions in the collection) give the same values: stray
+# spaces trimmed, accents kept.
+add_executable(
+  tst_diagramcontext
+  tst_diagramcontext.cpp
+  ${QET_DIR}/sources/diagramcontext.cpp
+  ${QET_DIR}/sources/qet.cpp
+  ${QET_DIR}/sources/qeticons.cpp
+  ${QET_DIR}/sources/shortcutmanager.cpp)
+add_test(NAME tst_diagramcontext COMMAND tst_diagramcontext)
+target_include_directories(tst_diagramcontext PRIVATE ${QET_DIR}/sources)
+target_link_libraries(tst_diagramcontext PRIVATE Qt::Test Qt::Widgets Qt::Xml pugixml::pugixml)

tests/qttest/tst_diagramcontext.cpp

@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <QtTest>
+
+#include "diagramcontext.h"
+#include "qetapp.h"
+
+QString QETApp::m_interface_language;
+
+/**
+	DiagramContext::fromXml() has two readers: QDom, for projects, and
+	pugixml, for element definitions in the collection. Both must give the
+	values the next save writes -- stray spaces around real content trimmed,
+	accented characters kept.
+*/
+class tst_diagramcontext : public QObject
+{
+	Q_OBJECT
+
+	static QByteArray xml(const QString &value)
+	{
+		return QStringLiteral(
+				   "<elementInformations>"
+				   "<elementInformation name=\"v\" show=\"1\">%1</elementInformation>"
+				   "</elementInformations>")
+				.arg(value)
+				.toUtf8();
+	}
+
+	static QString fromDom(const QByteArray &data)
+	{
+		QDomDocument doc;
+		if (!doc.setContent(data)) return QStringLiteral("<parse error>");
+		DiagramContext dc;
+		dc.fromXml(doc.documentElement(), QStringLiteral("elementInformation"));
+		return dc.value(QStringLiteral("v")).toString();
+	}
+
+	static QString fromPugi(const QByteArray &data)
+	{
+		pugi::xml_document doc;
+		if (!doc.load_buffer(data.constData(), size_t(data.size())))
+			return QStringLiteral("<parse error>");
+		DiagramContext dc;
+		dc.fromXml(doc.document_element(), QStringLiteral("elementInformation"));
+		return dc.value(QStringLiteral("v")).toString();
+	}
+
+private slots:
+	void bothReadersAgree_data()
+	{
+		QTest::addColumn<QString>("value");
+		QTest::addColumn<QString>("expected");
+
+		QTest::newRow("plain")       << "PRISE" << "PRISE";
+		QTest::newRow("stray spaces") << " PRISE  " << "PRISE";
+		QTest::newRow("accents")     << "Armoire façade été" << "Armoire façade été";
+		QTest::newRow("accents and stray spaces") << "  Moteur à cage " << "Moteur à cage";
+		QTest::newRow("non-Latin")   << "Двигатель 電機" << "Двигатель 電機";
+	}
+
+	void bothReadersAgree()
+	{
+		QFETCH(QString, value);
+		QFETCH(QString, expected);
+		QCOMPARE(fromDom(xml(value)), expected);
+		QCOMPARE(fromPugi(xml(value)), expected);
+	}
+};
+
+QTEST_APPLESS_MAIN(tst_diagramcontext)
+
+#include "tst_diagramcontext.moc"

tests/qttest/tst_resaveunchanged.cpp

@@ -5,6 +5,7 @@
 #include <QFile>
 #include <QProcess>
 #include <QProcessEnvironment>
+#include <QRegularExpression>
 #include <QTemporaryDir>
 
 // Saving a project that was just saved must change nothing. Two things
@@ -16,7 +17,8 @@
 //  - information values were trimmed on save but not on load, so a label
 //    with stray spaces kept them in its displayed copy until the project
 //    was opened again (m_000.qet).
-// Runs the real binary's --resave twice on each example.
+// Runs the real binary's --resave twice on every example, and on a
+// project whose title block holds a value that is a single space (#973).
 class tst_resaveunchanged : public QObject
 {
 	Q_OBJECT
@@ -56,17 +58,23 @@ private slots:
 		QVERIFY(QFile::exists(QStringLiteral(QET_TEST_BINARY_PATH)));
 	}
 
+	// Projet_vierge.qet has empty information values, m_000.qet values
+	// with stray spaces; every other example is here so a new cause shows.
 	void secondSaveChangesNothing_data()
 	{
 		QTest::addColumn<QString>("project");
-		QTest::newRow("empty information values") << QStringLiteral("Projet_vierge.qet");
-		QTest::newRow("information values with stray spaces") << QStringLiteral("m_000.qet");
+		const QDir examples(QStringLiteral(QET_EXAMPLES_DIR));
+		const QStringList projects =
+				examples.entryList({QStringLiteral("*.qet")}, QDir::Files, QDir::Name);
+		QVERIFY(!projects.isEmpty());
+		for (const QString &project : projects)
+			QTest::newRow(project.toUtf8().constData()) << examples.filePath(project);
 	}
 
 	void secondSaveChangesNothing()
 	{
 		QFETCH(QString, project);
-		const QString first = resave(QStringLiteral(QET_EXAMPLES_DIR "/") + project);
+		const QString first = resave(project);
 		QVERIFY2(!first.isEmpty(), "first --resave failed");
 		const QString second = resave(first);
 		QVERIFY2(!second.isEmpty(), "second --resave failed");
@@ -74,6 +82,38 @@ private slots:
 		QVERIFY(!a.isEmpty());
 		QVERIFY2(a == b, "the second save changed the file");
 	}
+
+	// A title-block value that is a single space is kept through two saves
+	// (#973), and a value with accents comes back as it went in.
+	void singleSpaceValueKept()
+	{
+		QByteArray xml = read(QStringLiteral(QET_EXAMPLES_DIR "/Projet_vierge.qet"));
+		QVERIFY(xml.contains("<properties>"));
+		xml.replace("<properties>",
+					"<properties>"
+					"<property show=\"1\" name=\"space\"> </property>"
+					"<property show=\"1\" name=\"accents\">Armoire façade été</property>");
+		const QString in = m_dir.filePath(QStringLiteral("space.qet"));
+		QFile f(in);
+		QVERIFY(f.open(QIODevice::WriteOnly));
+		f.write(xml);
+		f.close();
+
+		const QString first = resave(in);
+		QVERIFY2(!first.isEmpty(), "first --resave failed");
+		const QString second = resave(first);
+		QVERIFY2(!second.isEmpty(), "second --resave failed");
+		const QByteArray a = read(first), b = read(second);
+		QVERIFY2(a == b, "the second save changed the file");
+
+		const QString saved = QString::fromUtf8(b);
+		QVERIFY2(saved.contains(QRegularExpression(
+					 QStringLiteral("<property [^>]*name=\"space\"[^>]*> </property>"))),
+				 "the single-space value was lost");
+		QVERIFY2(saved.contains(QRegularExpression(
+					 QStringLiteral("<property [^>]*name=\"accents\"[^>]*>Armoire façade été</property>"))),
+				 "the accented value changed");
+	}
 };
 
 QTEST_APPLESS_MAIN(tst_resaveunchanged)