From 86c044176f16674616a20cd8e6a88b5a2dcf3775 Mon Sep 17 00:00:00 2001
From: Ivan Solovev <ivan.solovev@qt.io>
Date: Mon, 8 May 2023 18:55:17 +0200
Subject: [PATCH] Extend QFuture continuations tests
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Create tests to check that the continuations attached to ready futures
are immediately executed, and that the proper handlers are selected.

These checks were missing from the overall test set, which was detected
while working on the linked issue.

Task-number: QTBUG-112958
Change-Id: Iae97e4b9dfb1e016869693a5162f72e027ca7f5e
Reviewed-by: Arno Rehn <a.rehn@menlosystems.com>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
---
 .../corelib/thread/qfuture/tst_qfuture.cpp    | 103 ++++++++++++++++++
 1 file changed, 103 insertions(+)

diff --git a/tests/auto/corelib/thread/qfuture/tst_qfuture.cpp b/tests/auto/corelib/thread/qfuture/tst_qfuture.cpp
index 118a005de5..08c417019e 100644
--- a/tests/auto/corelib/thread/qfuture/tst_qfuture.cpp
+++ b/tests/auto/corelib/thread/qfuture/tst_qfuture.cpp
@@ -209,6 +209,7 @@ private slots:
     void rejectPendingResultOverwrite();
 
     void createReadyFutures();
+    void continuationsAfterReadyFutures();
 
     void getFutureInterface();
     void convertQMetaType();
@@ -4261,6 +4262,108 @@ QT_WARNING_POP
     }
 }
 
+void tst_QFuture::continuationsAfterReadyFutures()
+{
+    // continuations without a context
+    {
+        QFuture<int> f = QtFuture::makeReadyValueFuture(42)
+                .then([](int val) {
+                    return val + 10;
+                })
+                .onCanceled([]() {
+                    return -1;
+                });
+        QCOMPARE(f.result(), 52);
+    }
+    {
+        auto rangeF = QtFuture::makeReadyRangeFuture({1, 2, 3});
+        QFuture<int> f = rangeF
+                .then([vals = rangeF.results()](auto) {
+                    return vals.last();
+                })
+                .onCanceled([]() {
+                    return -1;
+                });
+        QCOMPARE(f.result(), 3);
+    }
+    {
+        QFuture<int> f = QtFuture::makeReadyVoidFuture()
+                .then([]() {
+                    return 1;
+                })
+                .onCanceled([]() {
+                    return -1;
+                });
+        QCOMPARE(f.result(), 1);
+    }
+#ifndef QT_NO_EXCEPTIONS
+    {
+        QException e;
+        QFuture<int> f = QtFuture::makeExceptionalFuture<int>(e)
+                .then([](int) {
+                    return 1;
+                })
+                .onCanceled([]() {
+                    return -1;
+                })
+                .onFailed([](const QException &) {
+                    return -2;
+                });
+        QCOMPARE(f.result(), -2);
+    }
+#endif
+
+    // continuations with a context
+    QObject context;
+    {
+        QFuture<int> f = QtFuture::makeReadyValueFuture(42)
+                .then(&context, [](int val) {
+                    return val + 10;
+                })
+                .onCanceled([]() {
+                    return -1;
+                });
+        QCOMPARE(f.result(), 52);
+    }
+    {
+        auto rangeF = QtFuture::makeReadyRangeFuture({1, 2, 3});
+        QFuture<int> f = rangeF
+                .then(&context, [vals = rangeF.results()](auto) {
+                    return vals.last();
+                })
+                .onCanceled([]() {
+                    return -1;
+                });
+        QCOMPARE(f.result(), 3);
+    }
+    {
+        QFuture<int> f = QtFuture::makeReadyVoidFuture()
+                .then(&context, []() {
+                    return 1;
+                })
+                .onCanceled([]() {
+                    return -1;
+                });
+        QCOMPARE(f.result(), 1);
+    }
+#ifndef QT_NO_EXCEPTIONS
+    {
+        QException e;
+        QFuture<int> f = QtFuture::makeExceptionalFuture<int>(e)
+                .then(&context, [](int) {
+                    return 1;
+                })
+                .onCanceled([]() {
+                    return -1;
+                })
+                .onFailed([](const QException &) {
+                    return -2;
+                });
+        QCOMPARE(f.result(), -2);
+    }
+#endif
+}
+
 void tst_QFuture::getFutureInterface()
 {
     const int val = 42;