Fix duplicate main() linker error in tests

- Merged test_mainwindow.cpp tests into test_main.cpp to have single main()
- Removed test_mainwindow.cpp from CMakeLists.txt test executable
- Qt test executables should have only one main() via QTEST_MAIN()

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Entire-Checkpoint: 0f6858921c53

qt6-after/qt6-migrated-benchmark/CMakeLists.txt

@@ -61,7 +61,6 @@ enable_testing()
 # Add test executable
 add_executable(Qt6MigratedBenchmarkTest
     tests/test_main.cpp
-    tests/test_mainwindow.cpp
     MainWindow.h
     MainWindow.cpp
 )

qt6-after/qt6-migrated-benchmark/tests/test_main.cpp

@@ -1,3 +1,5 @@
+#include "MainWindow.h"
+
 #include <QtTest/QtTest>
 
 class TestMainWindow : public QObject
@@ -9,6 +11,10 @@ class TestMainWindow : public QObject
     void testValidateInputInvalid();
     void testValidateInputEmpty();
     void testValidateInputMixedCase();
+    void testMainWindowCreation();
+    void testWindowTitle();
+    void testValidateInputMethod();
+    void testGetScreenInfo();
 };
 
 void TestMainWindow::testValidateInputValid()
@@ -47,6 +53,36 @@ void TestMainWindow::testValidateInputMixedCase()
     QVERIFY(pattern.match("aBcDeF999").hasMatch());
 }
 
+void TestMainWindow::testMainWindowCreation()
+{
+    MainWindow window;
+    QVERIFY(!window.windowTitle().isEmpty());
+}
+
+void TestMainWindow::testWindowTitle()
+{
+    MainWindow window;
+    QCOMPARE(window.windowTitle(), QStringLiteral("Qt6 Legacy Migration Benchmark"));
+}
+
+void TestMainWindow::testValidateInputMethod()
+{
+    MainWindow window;
+
+    QVERIFY(window.validateInput(QStringLiteral("Test123")));
+    QVERIFY(window.validateInput(QStringLiteral("abc456")));
+    QVERIFY(!window.validateInput(QStringLiteral("123Test")));
+    QVERIFY(!window.validateInput(QStringLiteral("")));
+}
+
+void TestMainWindow::testGetScreenInfo()
+{
+    MainWindow window;
+    QString info = window.getScreenInfo();
+    QVERIFY(!info.isEmpty());
+    QVERIFY(info.contains(QStringLiteral("Screen:")));
+}
+
 QTEST_MAIN(TestMainWindow)
 
 #include "test_main.moc"

qt6-after/qt6-migrated-benchmark/tests/test_mainwindow.cpp

@@ -1,49 +0,0 @@
-#include "MainWindow.h"
-
-#include <QApplication>
-#include <QtTest/QtTest>
-
-class TestMainWindowWidget : public QObject
-{
-    Q_OBJECT
-
-  private slots:
-    void testMainWindowCreation();
-    void testWindowTitle();
-    void testValidateInputMethod();
-    void testGetScreenInfo();
-};
-
-void TestMainWindowWidget::testMainWindowCreation()
-{
-    MainWindow window;
-    QVERIFY(!window.windowTitle().isEmpty());
-}
-
-void TestMainWindowWidget::testWindowTitle()
-{
-    MainWindow window;
-    QCOMPARE(window.windowTitle(), QStringLiteral("Qt6 Legacy Migration Benchmark"));
-}
-
-void TestMainWindowWidget::testValidateInputMethod()
-{
-    MainWindow window;
-
-    QVERIFY(window.validateInput(QStringLiteral("Test123")));
-    QVERIFY(window.validateInput(QStringLiteral("abc456")));
-    QVERIFY(!window.validateInput(QStringLiteral("123Test")));
-    QVERIFY(!window.validateInput(QStringLiteral("")));
-}
-
-void TestMainWindowWidget::testGetScreenInfo()
-{
-    MainWindow window;
-    QString info = window.getScreenInfo();
-    QVERIFY(!info.isEmpty());
-    QVERIFY(info.contains(QStringLiteral("Screen:")));
-}
-
-QTEST_MAIN(TestMainWindowWidget)
-
-#include "test_mainwindow.moc"