Add QDebug::toString()

This template function streams the given object into a QDebug instance
that operates on a string, and then returns that string.

This function is useful for cases where you need the textual
representation of an object for debugging, but cannot use operator<<.
A good example of this is when writing tests where you want to provide
a useful failure message involving details about an object, but must
provide it in a string to e.g. QVERIFY2.

[ChangeLog][QtCore][QDebug] Added static template toString() function,
which streams the given object into a QDebug instance that operates on
a string, and then returns that string.

Fixes: QTBUG-82309
Change-Id: I8411394e899dedad19cec788d779a4515d52ba11
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 23 insertions, 0 deletions

diff --git a/tests/auto/corelib/io/qdebug/tst_qdebug.cpp b/tests/auto/corelib/io/qdebug/tst_qdebug.cpp
index 584e66a7db..7b9e614cf7 100644
--- a/tests/auto/corelib/io/qdebug/tst_qdebug.cpp
+++ b/tests/auto/corelib/io/qdebug/tst_qdebug.cpp
@@ -66,6 +66,7 @@ private slots:
     void resetFormat() const;
     void defaultMessagehandler() const;
     void threadSafety() const;
+    void toString() const;
 };
 
 void tst_QDebug::assignment() const
@@ -740,6 +741,28 @@ void tst_QDebug::threadSafety() const
     }
 }
 
+void tst_QDebug::toString() const
+{
+    // By reference.
+    {
+        MyPoint point(3, 4);
+        QString expectedString;
+        QDebug stream(&expectedString);
+        stream << point;
+        QCOMPARE(QDebug::toString(point), expectedString);
+    }
+
+    // By pointer.
+    {
+        QObject qobject;
+        qobject.setObjectName("test");
+        QString expectedString;
+        QDebug stream(&expectedString);
+        stream << &qobject;
+        QCOMPARE(QDebug::toString(&qobject), expectedString);
+    }
+}
+
 // Should compile: instentiation of unrelated operator<< should not cause cause compilation
 // error in QDebug operators (QTBUG-47375)
 class TestClassA {};