test/operators/take_last.cpp

#include "../test.h"
#include <rxcpp/operators/rx-take_last.hpp>

SCENARIO("take last 0", "[take_last][operators]"){
    GIVEN("a source"){
        auto sc = rxsc::make_test();
        auto w = sc.create_worker();
        const rxsc::test::messages<int> on;

        auto xs = sc.make_hot_observable({
            on.next(150, 1),
            on.next(210, 2),
            on.next(220, 3),
            on.next(230, 4),
            on.next(240, 5),
            on.completed(250)
        });

        WHEN("0 last values are taken"){

            auto res = w.start(
                [xs]() {
                    return xs
                        | rxo::take_last(0)
                        // forget type to workaround lambda deduction bug on msvc 2013
                        | rxo::as_dynamic();
                }
            );

            THEN("the output only contains the completion event"){
                auto required = rxu::to_vector({
                    on.completed(250)
                });
                auto actual = res.get_observer().messages();
                REQUIRE(required == actual);
            }

            THEN("there was 1 subscription/unsubscription to the source"){
                auto required = rxu::to_vector({
                    on.subscribe(200, 250)
                });
                auto actual = xs.subscriptions();
                REQUIRE(required == actual);
            }

        }
    }
}

SCENARIO("take last 1", "[take_last][operators]"){
    GIVEN("a source"){
        auto sc = rxsc::make_test();
        auto w = sc.create_worker();
        const rxsc::test::messages<int> on;

        auto xs = sc.make_hot_observable({
            on.next(150, 1),
            on.next(210, 2),
            on.next(220, 3),
            on.next(230, 4),
            on.next(240, 5),
            on.completed(250)
        });

        WHEN("1 last value is taken"){

            auto res = w.start(
                [xs]() {
                    return xs
                        .take_last(1)
                        // forget type to workaround lambda deduction bug on msvc 2013
                        .as_dynamic();
                }
            );

            THEN("the output only contains items sent while subscribed"){
                auto required = rxu::to_vector({
                    on.next(250, 5),
                    on.completed(250)
                });
                auto actual = res.get_observer().messages();
                REQUIRE(required == actual);
            }

            THEN("there was 1 subscription/unsubscription to the source"){
                auto required = rxu::to_vector({
                    on.subscribe(200, 250)
                });
                auto actual = xs.subscriptions();
                REQUIRE(required == actual);
            }

        }
    }
}

SCENARIO("take last 2", "[take_last][operators]"){
    GIVEN("a source"){
        auto sc = rxsc::make_test();
        auto w = sc.create_worker();
        const rxsc::test::messages<int> on;

        auto xs = sc.make_hot_observable({
            on.next(150, 1),
            on.next(210, 2),
            on.next(220, 3),
            on.next(230, 4),
            on.next(240, 5),
            on.completed(250)
        });

        WHEN("2 last values are taken"){

            auto res = w.start(
                [xs]() {
                    return xs
                        .take_last(2)
                        // forget type to workaround lambda deduction bug on msvc 2013
                        .as_dynamic();
                }
            );

            THEN("the output only contains items sent while subscribed"){
                auto required = rxu::to_vector({
                    on.next(250, 4),
                    on.next(250, 5),
                    on.completed(250)
                });
                auto actual = res.get_observer().messages();
                REQUIRE(required == actual);
            }

            THEN("there was 1 subscription/unsubscription to the source"){
                auto required = rxu::to_vector({
                    on.subscribe(200, 250)
                });
                auto actual = xs.subscriptions();
                REQUIRE(required == actual);
            }

        }
    }
}

SCENARIO("take last 10, complete before all elements are taken", "[take_last][operators]"){
    GIVEN("a source"){
        auto sc = rxsc::make_test();
        auto w = sc.create_worker();
        const rxsc::test::messages<int> on;

        auto xs = sc.make_hot_observable({
            on.next(150, 1),
            on.next(210, 2),
            on.next(220, 3),
            on.next(230, 4),
            on.next(240, 5),
            on.completed(250)
        });

        WHEN("10 last values are taken"){

            auto res = w.start(
                [xs]() {
                    return xs
                        .take_last(10)
                        // forget type to workaround lambda deduction bug on msvc 2013
                        .as_dynamic();
                }
            );

            THEN("the output only contains items sent while subscribed"){
                auto required = rxu::to_vector({
                    on.next(250, 2),
                    on.next(250, 3),
                    on.next(250, 4),
                    on.next(250, 5),
                    on.completed(250)
                });
                auto actual = res.get_observer().messages();
                REQUIRE(required == actual);
            }

            THEN("there was 1 subscription/unsubscription to the source"){
                auto required = rxu::to_vector({
                    on.subscribe(200, 250)
                });
                auto actual = xs.subscriptions();
                REQUIRE(required == actual);
            }

        }
    }
}

SCENARIO("no items to take_last", "[take_last][operators]"){
    GIVEN("a source"){
        auto sc = rxsc::make_test();
        auto so = rx::synchronize_in_one_worker(sc);
        auto w = sc.create_worker();
        const rxsc::test::messages<int> on;

        auto xs = sc.make_hot_observable({
            on.next(150, 1)
        });

        WHEN("2 last values are taken"){

            auto res = w.start(
                [so, xs]() {
                    return xs
                        .take_last(2)
                        // forget type to workaround lambda deduction bug on msvc 2013
                        .as_dynamic();
                }
            );

            THEN("the output is empty"){
                auto required = std::vector<rxsc::test::messages<int>::recorded_type>();
                auto actual = res.get_observer().messages();
                REQUIRE(required == actual);
            }

            THEN("there was 1 subscription/unsubscription to the source"){
                auto required = rxu::to_vector({
                    on.subscribe(200, 1000)
                });
                auto actual = xs.subscriptions();
                REQUIRE(required == actual);
            }
        }
    }
}

SCENARIO("take_last, source observable emits an error", "[take_last][operators]"){
    GIVEN("a source"){
        auto sc = rxsc::make_test();
        auto so = rx::synchronize_in_one_worker(sc);
        auto w = sc.create_worker();
        const rxsc::test::messages<int> on;

        std::runtime_error ex("on_error from source");

        auto xs = sc.make_hot_observable({
            on.next(150, 1),
            on.error(250, ex)
        });

        WHEN("2 last values are taken"){

            auto res = w.start(
                [so, xs]() {
                    return xs
                        .take_last(2)
                        // forget type to workaround lambda deduction bug on msvc 2013
                        .as_dynamic();
                }
            );

            THEN("the output contains only an error message"){
                auto required = rxu::to_vector({
                    on.error(250, ex)
                });
                auto actual = res.get_observer().messages();
                REQUIRE(required == actual);
            }

            THEN("there was 1 subscription/unsubscription to the source"){
                auto required = rxu::to_vector({
                    on.subscribe(200, 250)
                });
                auto actual = xs.subscriptions();
                REQUIRE(required == actual);
            }

        }
    }
}