QTest: de-inline QVERIFY_THROWS_EXCEPTION message formatting

Extract Method QTest::qCaught() to take the string handling out of the
header. This should help a bit in speeding up compilation of large
unit test files (provided they use QVERIFY_THROWS_EXCEPTION), although
I have no data to support that.

Since we changed the error message, update the selftest accordingly.

Change-Id: Id4a3c8c34d5df8d0c7a861106d269097f4a6de5c
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

2 files changed, 38 insertions, 5 deletions

diff --git a/src/testlib/qtestcase.cpp b/src/testlib/qtestcase.cpp
index 4d0b30a844..db7c4d4a3d 100644
--- a/src/testlib/qtestcase.cpp
+++ b/src/testlib/qtestcase.cpp
@@ -2073,6 +2073,40 @@ bool QTest::qExpectFail(const char *dataIndex, const char *comment,
     return QTestResult::expectFail(dataIndex, qstrdup(comment), mode, file, line);
 }
 
+/*!
+    \internal
+
+    Executes qFail() following a failed QVERIFY_THROWS_EXCEPTION or
+    QVERIFY_THROWS_NO_EXCEPTION, passing a suitable message created from \a expected,
+    \a what, along with \a file and \a line.
+
+    The \a expected parameter contains the type of the exception that is expected to
+    be thrown, or \nullptr, if no exception was expected.
+
+    The \a what parameter contains the result of \c{std::exception::what()}, or nullptr,
+    if a non-\c{std::exception}-derived exception was caught.
+
+    The \a file and \a line parameters hold expansions of the \c{__FILE__} and \c{__LINE__}
+    macros, respectively.
+*/
+void QTest::qCaught(const char *expected, const char *what, const char *file, int line)
+{
+    auto message = [&] {
+        const auto exType  = what ? "std::" : "unknown ";
+        const auto ofType  = expected ? " of type " : "";
+        const auto no      = expected ? "an" : "no";
+        const auto withMsg = what ? " with message " : "";
+        const auto protect = [](const char *s) { return s ? s : ""; };
+
+        return QString::asprintf("Expected %s exception%s%s to be thrown, "
+                                 "but caught %sexception%s%s",
+                                 no, ofType, protect(expected),
+                                 exType, withMsg, protect(what));
+    };
+    qFail(message().toUtf8().constData(), file, line);
+}
+
+
 #if QT_DEPRECATED_SINCE(6, 3)
 /*!
   \internal
diff --git a/src/testlib/qtestcase.h b/src/testlib/qtestcase.h
index eea99e26e4..be852bca94 100644
--- a/src/testlib/qtestcase.h
+++ b/src/testlib/qtestcase.h
@@ -115,13 +115,10 @@ inline void useVerifyThrowsException() {}
                 /* success */\
             }\
         } QT_CATCH (const std::exception &e) {\
-            QByteArray msg = QByteArray() + "Expected exception of type " #exceptiontype \
-                             " to be thrown but std::exception caught with message: " + e.what(); \
-            QTest::qFail(msg.constData(), __FILE__, __LINE__);\
+            QTest::qCaught(#exceptiontype, e.what(), __FILE__, __LINE__);\
             return;\
         } QT_CATCH (...) {\
-            QTest::qFail("Expected exception of type " #exceptiontype " to be thrown" \
-                         " but unknown exception caught", __FILE__, __LINE__);\
+            QTest::qCaught(#exceptiontype, nullptr, __FILE__, __LINE__);\
             QT_RETHROW;\
         }\
     } while (false)
@@ -323,6 +320,8 @@ namespace QTest
     Q_TESTLIB_EXPORT void qSkip(const char *message, const char *file, int line);
     Q_TESTLIB_EXPORT bool qExpectFail(const char *dataIndex, const char *comment, TestFailMode mode,
                            const char *file, int line);
+    Q_DECL_COLD_FUNCTION
+    Q_TESTLIB_EXPORT void qCaught(const char *expected, const char *what, const char *file, int line);
 #if QT_DEPRECATED_SINCE(6, 3)
     QT_DEPRECATED_VERSION_X_6_3("Use qWarning() instead")
     Q_TESTLIB_EXPORT void qWarn(const char *message, const char *file = nullptr, int line = 0);