QTestLib: prepare QVERIFY_THROWS_EXCEPTION for FAILED_ACTION = throw

We can't have a QTEST_FAILED_ACTION in a try-block if we intend to
allow QTEST_FAILED_ACTION to be a throw statement.

We could, of course, add a whitelisting catch-block for the eventual
TestFailedException, but as of now, the intent it to give users full
control over the definition of QTEST_FAILED_ACTION, and they may have
their own idea of what to throw.

So add a bool variable to record whether no exception was thrown and
use it to drag QTEST_FAILED_ACTION out of the try block. It's ok to be
in catch blocks, no action needed there.

Change-Id: I0b004e43b1db82cd8b5b12f900ed985e58a56807
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

src/testlib/qtestcase.h

@@ -116,17 +116,20 @@ inline void useVerifyThrowsException() {}
 
 #  define QVERIFY_THROWS_EXCEPTION(exceptiontype, ...) \
     do {\
+        bool qverify_throws_exception_did_not_throw = false; \
         QT_TRY {\
             __VA_ARGS__; \
             QTest::qFail("Expected exception of type " #exceptiontype " to be thrown" \
                          " but no exception caught", __FILE__, __LINE__); \
-            QTEST_FAIL_ACTION; \
+            qverify_throws_exception_did_not_throw = true; \
         } QT_CATCH (const exceptiontype &) { \
             /* success */ \
         } QT_CATCH (...) {\
             QTest::qCaught(#exceptiontype, __FILE__, __LINE__); \
             QTEST_FAIL_ACTION; \
         }\
+        if (qverify_throws_exception_did_not_throw) \
+            QTEST_FAIL_ACTION; \
     } while (false)
 
 #else // QT_NO_EXCEPTIONS