Compilation error in qsignalspy_wrapper.cpp

My build script:

  cmake -B build -S $_pkgfn -G Ninja \
    -DCMAKE_INSTALL_PREFIX=/usr \
    -DCMAKE_BUILD_TYPE=None \
    -DSHIBOKEN_PYTHON_LIBRARIES=`pkgconf python3-embed ff--libs` \
    -DBUILD_TESTS=OFF \
    -DFORCE_LIMITED_API=no \
    -DNO_QT_TOOLS=yes
  PYTHONPATH="$PWD"/build/sources \
  cmake --build build

qt6-base version: 6.8.0 (sic - can't compile the corresponding master version of pyside 6.8: https://bugreports.qt.io/browse/PYSIDE-2865 )

Result:

[1320/1776] Building CXX object sources/pyside6/PySide6/QtTest/CMakeFiles/QtTest.dir/PySide6/QtTest/qsignalspy_wrapper.cpp.o
FAILED: sources/pyside6/PySide6/QtTest/CMakeFiles/QtTest.dir/PySide6/QtTest/qsignalspy_wrapper.cpp.o 
/usr/bin/c++ -DQT_CORE_LIB -DQT_GUI_LIB -DQT_LEAN_HEADERS=1 -DQT_NO_DEBUG -DQT_TESTCASE_BUILDDIR=\"./pyside6/PySide6/QtTest\" -DQT_TESTCASE_SOURCEDIR=\"./pyside-setup-everywhere-src-6.7.2/sources/pyside6/PySide6/QtTest\" -DQT_TESTLIB_LIB -DQT_WIDGETS_LIB -DQtTest_EXPORTS -I./pyside-setup-everywhere-src-6.7.2/sources/pyside6/PySide6/QtTest/QtTest -I./pyside-setup-everywhere-src-6.7.2/sources/pyside6/PySide6/QtTest -I./pyside6/PySide6/QtTest -I./pyside-setup-everywhere-src-6.7.2/sources/pyside6/libpyside -I./pyside6/PySide6/QtCore/PySide6/QtCore -I./pyside6/PySide6/QtGui/PySide6/QtGui -I./pyside6/PySide6/QtWidgets/PySide6/QtWidgets -I./pyside-setup-everywhere-src-6.7.2/sources/pyside6/PySide6 -I./pyside-setup-everywhere-src-6.7.2/sources/shiboken6/libshiboken -I./shiboken6/libshiboken -I/usr/include/python3.10 -isystem /usr/include/qt6/QtCore -isystem /usr/include/qt6 -isystem /usr/include/qt6/QtGui -isystem /usr/include/qt6/QtWidgets -isystem /usr/include/qt6/QtTest -isystem /usr/lib/qt6/mkspecs/linux-g++ -march=native -mtune=native -O2 -pipe -fpermissive -fno-plt -fexceptions -Wformat -Wno-deprecated-declarations -Wno-stringop-overflow -Wno-unknown-pragmas -Wno-error=incompatible-pointer-types -fPIC -Wp,-D_GLIBCXX_ASSERTIONS -Wno-template-id-cdtor -Wno-zero-as-null-pointer-constant -fPIC -Wall -Wextra -Wno-strict-aliasing -Wno-cast-function-type -fvisibility=hidden -std=gnu++17 -fPIC   -fPIC -ffunction-sections -fdata-sections -fno-exceptions -mno-direct-extern-access -MD -MT sources/pyside6/PySide6/QtTest/CMakeFiles/QtTest.dir/PySide6/QtTest/qsignalspy_wrapper.cpp.o -MF sources/pyside6/PySide6/QtTest/CMakeFiles/QtTest.dir/PySide6/QtTest/qsignalspy_wrapper.cpp.o.d -o sources/pyside6/PySide6/QtTest/CMakeFiles/QtTest.dir/PySide6/QtTest/qsignalspy_wrapper.cpp.o -c ./pyside6/PySide6/QtTest/PySide6/QtTest/qsignalspy_wrapper.cpp
./pyside6/PySide6/QtTest/PySide6/QtTest/qsignalspy_wrapper.cpp: In function 'int Sbk_QSignalSpy_Init(PyObject*, PyObject*, PyObject*)':
./pyside6/PySide6/QtTest/PySide6/QtTest/qsignalspy_wrapper.cpp:127:28: error: expected type-specifier before 'QSignalSpyWrapper'
  127 |                 cptr = new QSignalSpyWrapper(emitter, signature.constData());
      |                            ^~~~~~~~~~~~~~~~~

Probably the same as https://bugreports.qt.io/browse/PYSIDE-2770

Nevertheless I don't understand why the tests are build despite -DBUILD_TESTS=OFF