ADD: Add test that closed connection throws

Author: threecgreen

tests/src/live_blocking_tests.cpp

@@ -563,6 +563,56 @@ TEST_F(LiveBlockingTests, TestConnectWhenGatewayNotUp) {
   ASSERT_THROW(builder_.BuildBlocking(), databento::TcpError);
 }
 
+TEST_F(LiveBlockingTests, TestNextRecordThrowsOnGatewayClose) {
+  constexpr auto kTsOut = false;
+  constexpr OhlcvMsg kRec{DummyHeader<OhlcvMsg>(RType::Ohlcv1M), 1, 2, 3, 4, 5};
+
+  bool should_close{};
+  std::mutex should_close_mutex;
+  std::condition_variable should_close_cv;
+  bool has_closed{};
+  std::mutex has_closed_mutex;
+  std::condition_variable has_closed_cv;
+  const mock::MockLsgServer mock_server{
+      dataset::kXnasItch, kTsOut,
+      [kRec, &should_close, &should_close_cv, &should_close_mutex, &has_closed,
+       &has_closed_cv, &has_closed_mutex](mock::MockLsgServer& self) {
+        self.Accept();
+        self.Authenticate();
+        self.SendRecord(kRec);
+        {
+          std::unique_lock<std::mutex> lock{should_close_mutex};
+          should_close_cv.wait(lock, [&should_close] { return should_close; });
+        }
+        self.Close();
+        {
+          const std::lock_guard<std::mutex> lock{has_closed_mutex};
+          has_closed = true;
+          has_closed_cv.notify_one();
+        }
+      }};
+
+  LiveBlocking target = builder_.SetDataset(dataset::kXnasItch)
+                            .SetSendTsOut(kTsOut)
+                            .SetAddress(kLocalhost, mock_server.Port())
+                            .BuildBlocking();
+  const auto rec = target.NextRecord();
+  ASSERT_TRUE(rec.Holds<OhlcvMsg>());
+  EXPECT_EQ(rec.Get<OhlcvMsg>(), kRec);
+  // Signal server to close connection
+  {
+    const std::lock_guard<std::mutex> lock{should_close_mutex};
+    should_close = true;
+    should_close_cv.notify_one();
+  }
+  // Wait for server to close
+  {
+    std::unique_lock<std::mutex> lock{has_closed_mutex};
+    has_closed_cv.wait(lock, [&has_closed] { return has_closed; });
+  }
+  ASSERT_THROW(target.NextRecord(), databento::DbnResponseError);
+}
+
 TEST_F(LiveBlockingTests, TestReconnectAndResubscribe) {
   constexpr auto kTsOut = false;
   constexpr TradeMsg kRec{DummyHeader<TradeMsg>(RType::Mbp0),