/usr/include/cppunit/extensions/ is in libcppunit-dev 1.13.2-2.1.
This file is owned by root:root, with mode 0o755.
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/usr/include/cppunit/extensions/AutoRegisterSuite.h
/usr/include/cppunit/extensions/ExceptionTestCaseDecorator.h
/usr/include/cppunit/extensions/HelperMacros.h
/usr/include/cppunit/extensions/Orthodox.h
/usr/include/cppunit/extensions/RepeatedTest.h
/usr/include/cppunit/extensions/TestCaseDecorator.h
/usr/include/cppunit/extensions/TestDecorator.h
/usr/include/cppunit/extensions/TestFactory.h
/usr/include/cppunit/extensions/TestFactoryRegistry.h
/usr/include/cppunit/extensions/TestFixtureFactory.h
/usr/include/cppunit/extensions/TestNamer.h
/usr/include/cppunit/extensions/TestSetUp.h
/usr/include/cppunit/extensions/TestSuiteBuilderContext.h
/usr/include/cppunit/extensions/TestSuiteFactory.h
/usr/include/cppunit/extensions/TypeInfoHelper.h