From 5d2fab5663876a38783c4ee8408954bc69fde6ed Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Wed, 29 Nov 2023 14:24:52 +0100
Subject: [PATCH] tst_tostring: support computed expected values

We need an owning container to keep the data alive when the _data
function computes the expected value instead of passing it as a
literal string, so replace the QByteArrayView we used so far with a
const QByteArray.

If a test failed, print the tail ends of the failing strings. This
is useful when toString() implementations printing the operands of
the failed toString()-under-test result comparison decide to
truncate the output. It works around the fact that we both test
toString() and use toString() to report any failure.

As a drive-by, add a missing blank line between function definitions.

Amends a2551c45d496c23045eb8451e080e75b2f8b42c1.

Change-Id: I0b217aeb1a6d475df8e8b9fb821046f1cceb1a3e
Reviewed-by: Jason McDonald <macadder1@gmail.com>
(cherry picked from commit 3a57885c3766d4ae203650d60881988c374e4148)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 tests/auto/testlib/tostring/tst_tostring.cpp | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/tests/auto/testlib/tostring/tst_tostring.cpp b/tests/auto/testlib/tostring/tst_tostring.cpp
index 3f12e0c7984..65e50fa511d 100644
--- a/tests/auto/testlib/tostring/tst_tostring.cpp
+++ b/tests/auto/testlib/tostring/tst_tostring.cpp
@@ -21,25 +21,34 @@ private slots:
 void tst_toString::addColumns()
 {
     QTest::addColumn<ToStringFunction>("fn");
-    QTest::addColumn<QByteArrayView>("expected");
+    QTest::addColumn<QByteArray>("expected");
     QTest::addColumn<QByteArrayView>("expr");
     QTest::addColumn<QByteArrayView>("file");
     QTest::addColumn<int>("line");
 }
+
 void tst_toString::testRows()
 {
     QFETCH(ToStringFunction, fn);
-    QFETCH(QByteArrayView, expected);
+    QFETCH(const QByteArray, expected);
     QFETCH(QByteArrayView, expr);
     QFETCH(QByteArrayView, file);
     QFETCH(int, line);
 
     std::unique_ptr<char []> ptr{fn()};
+    const auto len = qstrlen(ptr.get());
     QTest::qCompare(ptr.get(), expected, expr.data(), expected.data(), file.data(), line);
+    if (QTest::currentTestFailed()) {
+        qDebug("tail diff:\n"
+               "   actual:%s\n"
+               " expected:%s",
+               ptr.get() + len - std::min(size_t{40}, len),
+               expected.data() + expected.size() - std::min(qsizetype{40}, expected.size()));
+    }
 }
 
 template <typename T> void addRow(QByteArrayView name, T &&value, QByteArrayView expression,
-                                  QByteArrayView expected, QByteArrayView file, int line)
+                                  const QByteArray &expected, QByteArrayView file, int line)
 {
     ToStringFunction fn = [v = std::move(value)]() { return QTest::toString(v); };
     QTest::newRow(name.data()) << fn << expected << expression << file << line;