QTest: support nullptr in QCOMPARE

This allows to write
  QCOMPARE(ptr, nullptr);
instead of
  QVERIFY(ptr);

Task-number: QTBUG-49973
Change-Id: I6e1327d4327bcf17bd9b59de4352fdcaae98ac27
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

src/testlib/qtest.h

@@ -189,6 +189,11 @@ template<> inline char *toString(const QHostAddress &addr)
 }
 #endif
 
+inline char *toString(std::nullptr_t)
+{
+    return toString(QLatin1String("nullptr"));
+}
+
 template<>
 inline bool qCompare(QString const &t1, QLatin1String const &t2, const char *actual,
                     const char *expected, const char *file, int line)

src/testlib/qtestcase.cpp

@@ -2405,6 +2405,14 @@ bool QTest::compare_string_helper(const char *t1, const char *t2, const char *ac
     \internal
 */
 
+/*! \fn bool QTest::qCompare(T *t, std::nullptr_t, const char *actual, const char *expected, const char *file, int line)
+    \internal
+*/
+
+/*! \fn bool QTest::qCompare(std::nullptr_t, T *t, const char *actual, const char *expected, const char *file, int line)
+    \internal
+*/
+
 /*! \fn bool QTest::qCompare(T *t1, T *t2, const char *actual, const char *expected, const char *file, int line)
     \internal
 */

src/testlib/qtestcase.h

@@ -332,13 +332,27 @@ namespace QTest
     Q_TESTLIB_EXPORT bool qCompare(double const &t1, double const &t2,
                     const char *actual, const char *expected, const char *file, int line);
 
-    inline bool compare_ptr_helper(const void *t1, const void *t2, const char *actual,
+    inline bool compare_ptr_helper(const volatile void *t1, const volatile void *t2, const char *actual,
                                    const char *expected, const char *file, int line)
     {
         return compare_helper(t1 == t2, "Compared pointers are not the same",
                               toString(t1), toString(t2), actual, expected, file, line);
     }
 
+    inline bool compare_ptr_helper(const volatile void *t1, std::nullptr_t, const char *actual,
+                                   const char *expected, const char *file, int line)
+    {
+        return compare_helper(t1 == nullptr, "Compared pointers are not the same",
+                              toString(t1), toString(nullptr), actual, expected, file, line);
+    }
+
+    inline bool compare_ptr_helper(std::nullptr_t, const volatile void *t2, const char *actual,
+                                   const char *expected, const char *file, int line)
+    {
+        return compare_helper(nullptr == t2, "Compared pointers are not the same",
+                              toString(nullptr), toString(t2), actual, expected, file, line);
+    }
+
     Q_TESTLIB_EXPORT bool compare_string_helper(const char *t1, const char *t2, const char *actual,
                                       const char *expected, const char *file, int line);
 
@@ -388,6 +402,19 @@ namespace QTest
         return compare_ptr_helper(t1, t2, actual, expected, file, line);
     }
 
+    template <typename T>
+    inline bool qCompare(T *t1, std::nullptr_t, const char *actual, const char *expected,
+                        const char *file, int line)
+    {
+        return compare_ptr_helper(t1, nullptr, actual, expected, file, line);
+    }
+    template <typename T>
+    inline bool qCompare(std::nullptr_t, T *t2, const char *actual, const char *expected,
+                        const char *file, int line)
+    {
+        return compare_ptr_helper(nullptr, t2, actual, expected, file, line);
+    }
+
     template <typename T1, typename T2>
     inline bool qCompare(const T1 *t1, const T2 *t2, const char *actual, const char *expected,
                         const char *file, int line)

src/testlib/qtestcase.qdoc

@@ -905,6 +905,14 @@
     Returns a textual representation of the given \a string.
 */
 
+/*!
+    \fn char *QTest::toString(std::nullptr_t)
+    \overload
+    \since 5.8
+
+    Returns a string containing \c{nullptr}.
+*/
+
 /*!
     \fn char *QTest::toString(const QString &string)
     \overload

tests/auto/testlib/selftests/cmptest/tst_cmptest.cpp

@@ -128,6 +128,7 @@ private slots:
     void compare_registered_enums();
     void compare_class_enums();
     void compare_boolfuncs();
+    void compare_to_nullptr();
     void compare_pointerfuncs();
     void compare_tostring();
     void compare_tostring_data();
@@ -180,6 +181,24 @@ void tst_Cmptest::compare_boolfuncs()
     QCOMPARE(!boolfunc(), false);
 }
 
+namespace {
+template <typename T>
+T *null() Q_DECL_NOTHROW { return nullptr; }
+}
+
+void tst_Cmptest::compare_to_nullptr()
+{
+    QCOMPARE(null<int>(), nullptr);
+    QCOMPARE(null<const int>(), nullptr);
+    QCOMPARE(null<volatile int>(), nullptr);
+    QCOMPARE(null<const volatile int>(), nullptr);
+
+    QCOMPARE(nullptr, null<int>());
+    QCOMPARE(nullptr, null<const int>());
+    QCOMPARE(nullptr, null<volatile int>());
+    QCOMPARE(nullptr, null<const volatile int>());
+}
+
 static int i = 0;
 
 static int *intptr() { return &i; }

tests/auto/testlib/selftests/expected_cmptest.lightxml

@@ -33,6 +33,10 @@
 <Incident type="pass" file="" line="0" />
     <Duration msecs="0"/>
 </TestFunction>
+<TestFunction name="compare_to_nullptr">
+<Incident type="pass" file="" line="0" />
+    <Duration msecs="0"/>
+</TestFunction>
 <TestFunction name="compare_pointerfuncs">
 <Incident type="pass" file="" line="0" />
     <Duration msecs="0"/>

tests/auto/testlib/selftests/expected_cmptest.teamcity

@@ -12,6 +12,8 @@
 ##teamcity[testFinished name='compare_class_enums()']
 ##teamcity[testStarted name='compare_boolfuncs()']
 ##teamcity[testFinished name='compare_boolfuncs()']
+##teamcity[testStarted name='compare_to_nullptr()']
+##teamcity[testFinished name='compare_to_nullptr()']
 ##teamcity[testStarted name='compare_pointerfuncs()']
 ##teamcity[testFinished name='compare_pointerfuncs()']
 ##teamcity[testStarted name='compare_tostring(int, string)']

tests/auto/testlib/selftests/expected_cmptest.txt

@@ -12,6 +12,7 @@ FAIL!  : tst_Cmptest::compare_class_enums() Compared values are not the same
    Expected (MyClassEnum::MyClassEnumValue2): MyClassEnumValue2
    Loc: [tst_cmptest.cpp(168)]
 PASS   : tst_Cmptest::compare_boolfuncs()
+PASS   : tst_Cmptest::compare_to_nullptr()
 PASS   : tst_Cmptest::compare_pointerfuncs()
 FAIL!  : tst_Cmptest::compare_tostring(int, string) Compared values are not the same
    Actual   (actual)  : QVariant(int,123)
@@ -109,5 +110,5 @@ FAIL!  : tst_Cmptest::tryVerify() 'opaqueFunc() < 2' returned FALSE. ()
 FAIL!  : tst_Cmptest::tryVerify2() 'opaqueFunc() < 2' returned FALSE. (42)
    Loc: [tst_cmptest.cpp(439)]
 PASS   : tst_Cmptest::cleanupTestCase()
-Totals: 11 passed, 28 failed, 0 skipped, 0 blacklisted, 247ms
+Totals: 12 passed, 28 failed, 0 skipped, 0 blacklisted, 247ms
 ********* Finished testing of tst_Cmptest *********

tests/auto/testlib/selftests/expected_cmptest.xml

@@ -35,6 +35,10 @@
 <Incident type="pass" file="" line="0" />
     <Duration msecs="0"/>
 </TestFunction>
+<TestFunction name="compare_to_nullptr">
+<Incident type="pass" file="" line="0" />
+    <Duration msecs="0"/>
+</TestFunction>
 <TestFunction name="compare_pointerfuncs">
 <Incident type="pass" file="" line="0" />
     <Duration msecs="0"/>

tests/auto/testlib/selftests/expected_cmptest.xunitxml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<testsuite errors="0" failures="28" tests="18" name="tst_Cmptest">
+<testsuite errors="0" failures="28" tests="19" name="tst_Cmptest">
   <properties>
     <property value="@INSERT_QT_VERSION_HERE@" name="QTestVersion"/>
     <property value="@INSERT_QT_VERSION_HERE@" name="QtVersion"/>
@@ -20,6 +20,7 @@
    Expected (MyClassEnum::MyClassEnumValue2): MyClassEnumValue2" result="fail"/>
   </testcase>
   <testcase result="pass" name="compare_boolfuncs"/>
+  <testcase result="pass" name="compare_to_nullptr"/>
   <testcase result="pass" name="compare_pointerfuncs"/>
   <testcase result="fail" name="compare_tostring">
     <failure tag="int, string" message="Compared values are not the same