[Tests] Use QtTest for model contracts and signal spies (#7630)

Qt6::Test was linked into every test but never used. Add a small RAII
QAbstractItemModelTester helper and apply it to the deck list model, the card
database model and display proxy, and the sets model. Add QSignalSpy coverage
for the card-added and download-settings signals, and assert explicitly that a
card row is a leaf with no child columns (the tester does not check that).

The contract checker immediately found four model bugs, fixed here:
- DeckListModel allowed children below non-zero columns.
- CardDatabaseModel reported every card as a child of every card row.
- CardDatabaseModel reported six columns for a valid (leaf) card index.
- CardDatabaseDisplayModel claimed more rows were fetchable while rowCount
  already exposed them all, so fetchMore() inserted duplicates.

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

tests/model_contract/CMakeLists.txt

@@ -0,0 +1,17 @@
+cockatrice_add_test(
+  NAME
+  model_contract_test
+  SOURCES
+  ${VERSION_STRING_CPP}
+  model_contract_test.cpp
+  LIBS
+  libcockatrice_models
+  libcockatrice_card
+  libcockatrice_deck_list
+  libcockatrice_settings
+  INCLUDE_DIRS
+  ${CMAKE_CURRENT_SOURCE_DIR}/../support
+  ${CMAKE_CURRENT_SOURCE_DIR}/../carddatabase
+  DEFINITIONS
+  CARDDB_DATADIR="${CMAKE_SOURCE_DIR}/tests/carddatabase/data/"
+)

tests/model_contract/model_contract_test.cpp

@@ -0,0 +1,137 @@
+#include "libcockatrice/deck_list/deck_list.h"
+#include "libcockatrice/deck_list/tree/inner_deck_list_node.h"
+#include "libcockatrice/models/database/card_database_display_model.h"
+#include "libcockatrice/models/database/card_database_model.h"
+#include "libcockatrice/models/database/card_set/card_sets_model.h"
+#include "libcockatrice/models/deck_list/deck_list_model.h"
+#include "model_contract_checker.h"
+#include "test_card_database_path_provider.h"
+
+#include "gtest/gtest.h"
+#include <QAbstractItemModel>
+#include <QCoreApplication>
+#include <QModelIndex>
+#include <QSharedPointer>
+#include <QSignalSpy>
+#include <QString>
+#include <QTemporaryDir>
+#include <QVariant>
+#include <libcockatrice/card/card_info.h>
+#include <libcockatrice/card/database/card_database.h>
+#include <libcockatrice/card/game_specific_terms.h>
+#include <libcockatrice/card/printing/exact_card.h>
+#include <libcockatrice/interfaces/noop_card_preference_provider.h>
+#include <libcockatrice/interfaces/noop_card_set_priority_controller.h>
+#include <libcockatrice/settings/download_settings.h>
+
+namespace
+{
+QSharedPointer<DeckList> makeDeck()
+{
+    return QSharedPointer<DeckList>(new DeckList());
+}
+
+void loadCardDatabase(CardDatabase &database)
+{
+    database.loadCardDatabases();
+    ASSERT_EQ(database.getLoadStatus(), Ok);
+}
+
+TEST(ModelContract, DeckListModelKeepsContractWhileZonesAndCardsChange)
+{
+    const QSharedPointer<DeckList> deck = makeDeck();
+    DeckListModel model(nullptr, deck);
+
+    test_support::ModelContractChecker checker(&model);
+
+    ASSERT_NE(deck->getTree()->addCustomZone(DECK_ZONE_MAIN, "Removal"), nullptr);
+    model.rebuildTree();
+
+    CardInfoPtr bolt = CardInfo::newInstance("Lightning Bolt");
+    const QModelIndex added = model.addCard(ExactCard(bolt), DECK_ZONE_MAIN);
+    ASSERT_TRUE(added.isValid());
+
+    CardInfoPtr bears = CardInfo::newInstance("Grizzly Bears");
+    bears->setProperty(Mtg::MainCardType, "Creature");
+    const QModelIndex grouped = model.addCard(ExactCard(bears), "Removal");
+    ASSERT_TRUE(grouped.isValid());
+
+    ASSERT_TRUE(model.removeRows(grouped.row(), 1, grouped.parent()));
+}
+
+TEST(ModelContract, DeckListModelEmitsCardAddedSignal)
+{
+    const QSharedPointer<DeckList> deck = makeDeck();
+    DeckListModel model(nullptr, deck);
+    QSignalSpy spy(&model, &DeckListModel::cardAddedAt);
+
+    const QModelIndex added = model.addCard(ExactCard(CardInfo::newInstance("Lightning Bolt")), DECK_ZONE_MAIN);
+
+    ASSERT_TRUE(added.isValid());
+    EXPECT_EQ(spy.count(), 1);
+}
+
+TEST(ModelContract, CardDatabaseModelAndDisplayProxyKeepContract)
+{
+    CardDatabase database(nullptr, new NoopCardPreferenceProvider(), new TestCardDatabasePathProvider(),
+                          new NoopCardSetPriorityController());
+    ASSERT_NO_FATAL_FAILURE(loadCardDatabase(database));
+
+    CardDatabaseModel source(&database, false);
+    test_support::ModelContractChecker sourceChecker(&source);
+
+    CardDatabaseDisplayModel display;
+    display.setSourceModel(&source);
+    test_support::ModelContractChecker displayChecker(&display);
+
+    ASSERT_GT(source.rowCount(), 0);
+    EXPECT_EQ(display.rowCount(), source.rowCount());
+
+    // A card row is a leaf, so its index must not claim child columns. The
+    // tester does not check this, hence the explicit assertion.
+    const QModelIndex sourceCard = source.index(0, 0);
+    ASSERT_TRUE(sourceCard.isValid());
+    EXPECT_EQ(source.columnCount(sourceCard), 0);
+    const QModelIndex displayCard = display.index(0, 0);
+    ASSERT_TRUE(displayCard.isValid());
+    EXPECT_EQ(display.columnCount(displayCard), 0);
+
+    QSignalSpy dirtySpy(&display, &CardDatabaseDisplayModel::modelDirty);
+    display.setCardName("Do");
+    ASSERT_TRUE(dirtySpy.wait());
+    EXPECT_GT(display.rowCount(), 0);
+    EXPECT_LT(display.rowCount(), source.rowCount());
+}
+
+TEST(ModelContract, SetsModelKeepsContract)
+{
+    CardDatabase database(nullptr, new NoopCardPreferenceProvider(), new TestCardDatabasePathProvider(),
+                          new NoopCardSetPriorityController());
+    ASSERT_NO_FATAL_FAILURE(loadCardDatabase(database));
+
+    SetsModel model(&database);
+    test_support::ModelContractChecker checker(&model);
+
+    ASSERT_GT(model.rowCount(), 0);
+    ASSERT_GT(model.columnCount(), 0);
+}
+
+TEST(ModelContract, SettingsSignalIsObservableWithQSignalSpy)
+{
+    QTemporaryDir tempDir;
+    ASSERT_TRUE(tempDir.isValid());
+    DownloadSettings settings(tempDir.path() + "/", nullptr);
+    QSignalSpy spy(&settings, &DownloadSettings::downloadSpoilerStatusChanged);
+
+    settings.setDownloadSpoilerStatus(true);
+
+    ASSERT_EQ(spy.count(), 1);
+}
+} // namespace
+
+int main(int argc, char **argv)
+{
+    QCoreApplication app(argc, argv);
+    ::testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}