Dispatch view.event_added over the added half of the changed range

fb75510 pointed it at the removed half, so it fired on departing downloads instead.

src/core/view.cc

@@ -301,7 +301,7 @@ View::filter() {
     std::for_each(changed.begin(), splitChanged, [this](const auto& d) { rpc::call_object_d_nothrow(m_event_removed, d.get()); });
 
   if (!m_event_added.is_empty())
-    std::for_each(changed.begin(), splitChanged, [this](const auto& d) { rpc::call_object_d_nothrow(m_event_added, d.get()); });
+    std::for_each(splitChanged, changed.end(), [this](const auto& d) { rpc::call_object_d_nothrow(m_event_added, d.get()); });
 
   emit_changed();
 }

test/Makefile.am

@@ -1,4 +1,5 @@
 TESTS = \
+	rtorrent_Test_Core \
 	rtorrent_Test_Rpc \
 	rtorrent_Test_Src
 
@@ -7,6 +8,7 @@ check_PROGRAMS = $(TESTS)
 rtorrent_Test_LDADD = \
 	../src/libsub_root.a
 
+rtorrent_Test_Core_LDADD = $(rtorrent_Test_LDADD)
 rtorrent_Test_Rpc_LDADD = $(rtorrent_Test_LDADD)
 rtorrent_Test_Src_LDADD = $(rtorrent_Test_LDADD)
 
@@ -30,6 +32,10 @@ rtorrent_Test_Common = \
 	helpers/test_utils.h \
 	helpers/utils.h
 
+rtorrent_Test_Core_SOURCES = $(rtorrent_Test_Common) \
+	core/test_view.cc \
+	core/test_view.h
+
 rtorrent_Test_Rpc_SOURCES = $(rtorrent_Test_Common) \
 	rpc/test_command.cc \
 	rpc/test_command.h \
@@ -62,6 +68,8 @@ rtorrent_Test_Src_SOURCES = $(rtorrent_Test_Common) \
 	src/test_watch_ready_queue.cc \
 	src/test_watch_ready_queue.h
 
+rtorrent_Test_Core_CXXFLAGS = $(CPPUNIT_CFLAGS)
+rtorrent_Test_Core_LDFLAGS = $(CPPUNIT_LIBS) -ldl
 rtorrent_Test_Rpc_CXXFLAGS = $(CPPUNIT_CFLAGS)
 rtorrent_Test_Rpc_LDFLAGS = $(CPPUNIT_LIBS) -ldl
 rtorrent_Test_Src_CXXFLAGS = $(CPPUNIT_CFLAGS)

test/core/test_view.cc

@@ -0,0 +1,158 @@
+#include "config.h"
+
+#include "test/core/test_view.h"
+
+#include <algorithm>
+#include <cstddef>
+#include <deque>
+#include <memory>
+#include <set>
+#include <string>
+#include <vector>
+
+#include "command_helpers.h"
+#include "control.h"
+#include "core/download.h"
+#include "core/view.h"
+#include "globals.h"
+#include "rpc/parse_commands.h"
+
+CPPUNIT_TEST_SUITE_REGISTRATION(TestView);
+
+namespace {
+
+const char* filter_command  = "test.view.filter";
+const char* added_command   = "test.view.event_added";
+const char* removed_command = "test.view.event_removed";
+
+// View only stores these and hands them to the command layer as RPC targets,
+// which casts the pointer without reading through it.
+struct download_stub {
+  alignas(core::Download) std::byte storage[sizeof(core::Download)];
+};
+
+std::deque<download_stub>    stub_storage;
+std::vector<core::Download*> stub_downloads;
+
+std::set<core::Download*>    matches_filter;
+std::vector<core::Download*> added_events;
+std::vector<core::Download*> removed_events;
+
+std::shared_ptr<core::Download>
+make_stub_download() {
+  auto download = reinterpret_cast<core::Download*>(&stub_storage.emplace_back());
+
+  stub_downloads.push_back(download);
+
+  return std::shared_ptr<core::Download>(download, [](core::Download*) {});
+}
+
+// Renders a dispatch list as "d0,d2" so a failure names the downloads the
+// handler saw, not just how many there were.
+std::string
+describe(const std::vector<core::Download*>& downloads) {
+  std::string result;
+
+  for (const auto& download : downloads) {
+    auto itr = std::find(stub_downloads.begin(), stub_downloads.end(), download);
+
+    if (!result.empty())
+      result += ',';
+
+    result += 'd' + std::to_string(std::distance(stub_downloads.begin(), itr));
+  }
+
+  return result;
+}
+
+torrent::Object
+cmd_filter(core::Download* download, const torrent::Object&) {
+  return torrent::Object(static_cast<int64_t>(matches_filter.count(download)));
+}
+
+torrent::Object
+cmd_event_added(core::Download* download, const torrent::Object&) {
+  added_events.push_back(download);
+  return torrent::Object();
+}
+
+torrent::Object
+cmd_event_removed(core::Download* download, const torrent::Object&) {
+  removed_events.push_back(download);
+  return torrent::Object();
+}
+
+torrent::Object
+command_object(const char* command) {
+  return torrent::Object(std::string(command) + "=");
+}
+
+} // namespace
+
+void
+TestView::setUp() {
+  TestFixtureWithMainThread::setUp();
+
+  if (control == nullptr)
+    control = new Control;
+
+  if (!rpc::commands.has(filter_command)) {
+    CMD2_DL(filter_command, &cmd_filter);
+    CMD2_DL(added_command, &cmd_event_added);
+    CMD2_DL(removed_command, &cmd_event_removed);
+  }
+
+  stub_storage.clear();
+  stub_downloads.clear();
+  matches_filter.clear();
+  added_events.clear();
+  removed_events.clear();
+}
+
+void
+TestView::tearDown() {
+  TestFixtureWithMainThread::tearDown();
+}
+
+// d0 and d1 start visible and stop matching, d2 and d3 start filtered out and
+// start matching. The two halves are the same size on purpose: a test that
+// only counted the dispatches would pass even if both events were sent over
+// the same half of the changed range.
+void
+TestView::test_filter_dispatches_events_to_the_right_downloads() {
+  core::View view;
+  view.initialize("test_view");
+
+  auto d0 = make_stub_download();
+  auto d1 = make_stub_download();
+  auto d2 = make_stub_download();
+  auto d3 = make_stub_download();
+
+  view.insert(d0);
+  view.insert(d1);
+  view.insert(d2);
+  view.insert(d3);
+
+  view.set_visible(d0.get());
+  view.set_visible(d1.get());
+
+  CPPUNIT_ASSERT_EQUAL(core::View::size_type(2), view.size_visible());
+
+  matches_filter = {d2.get(), d3.get()};
+
+  view.set_filter(command_object(filter_command));
+  view.set_event_added(command_object(added_command));
+  view.set_event_removed(command_object(removed_command));
+
+  added_events.clear();
+  removed_events.clear();
+
+  view.filter();
+
+  CPPUNIT_ASSERT_EQUAL(std::string("d2,d3"), describe(added_events));
+  CPPUNIT_ASSERT_EQUAL(std::string("d0,d1"), describe(removed_events));
+
+  CPPUNIT_ASSERT_EQUAL(core::View::size_type(2), view.size_visible());
+  CPPUNIT_ASSERT(*view.begin_visible() == d2);
+  CPPUNIT_ASSERT(*(view.begin_visible() + 1) == d3);
+}

test/core/test_view.h

@@ -0,0 +1,15 @@
+#include "test/helpers/test_main_thread.h"
+
+class TestView : public TestFixtureWithMainThread {
+  CPPUNIT_TEST_SUITE(TestView);
+
+  CPPUNIT_TEST(test_filter_dispatches_events_to_the_right_downloads);
+
+  CPPUNIT_TEST_SUITE_END();
+
+public:
+  void setUp();
+  void tearDown();
+
+  void test_filter_dispatches_events_to_the_right_downloads();
+};