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test/async_latch_tests.cpp

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+///////////////////////////////////////////////////////////////////////////////
+// Copyright (c) Lewis Baker
+// Licenced under MIT license. See LICENSE.txt for details.
+///////////////////////////////////////////////////////////////////////////////
+
+#include <cppcoro/async_latch.hpp>
+#include <cppcoro/single_consumer_event.hpp>
+#include <cppcoro/task.hpp>
+#include <cppcoro/when_all_ready.hpp>
+#include <cppcoro/sync_wait.hpp>
+
+#include <ostream>
+#include "doctest/cppcoro_doctest.h"
+
+TEST_SUITE_BEGIN("async_latch");
+
+using namespace cppcoro;
+
+TEST_CASE("latch constructed with zero count is initially ready")
+{
+	async_latch latch(0);
+	CHECK(latch.is_ready());
+}
+
+TEST_CASE("latch constructed with negative count is initially ready")
+{
+	async_latch latch(-3);
+	CHECK(latch.is_ready());
+}
+
+TEST_CASE("count_down and is_ready")
+{
+	async_latch latch(3);
+	CHECK(!latch.is_ready());
+	latch.count_down();
+	CHECK(!latch.is_ready());
+	latch.count_down();
+	CHECK(!latch.is_ready());
+	latch.count_down();
+	CHECK(latch.is_ready());
+}
+
+TEST_CASE("count_down by n")
+{
+	async_latch latch(5);
+	latch.count_down(3);
+	CHECK(!latch.is_ready());
+	latch.count_down(2);
+	CHECK(latch.is_ready());
+}
+
+TEST_CASE("single awaiter")
+{
+	async_latch latch(2);
+	bool after = false;
+	sync_wait(when_all_ready(
+		[&]() -> task<>
+		{
+			co_await latch;
+			after = true;
+		}(),
+		[&]() -> task<>
+		{
+			CHECK(!after);
+			latch.count_down();
+			CHECK(!after);
+			latch.count_down();
+			CHECK(after);
+			co_return;
+		}()
+	));
+}
+
+TEST_CASE("multiple awaiters")
+{
+	async_latch latch(2);
+	bool after1 = false;
+	bool after2 = false;
+	bool after3 = false;
+	sync_wait(when_all_ready(
+		[&]() -> task<>
+		{
+			co_await latch;
+			after1 = true;
+		}(),
+		[&]() -> task<>
+		{
+			co_await latch;
+			after2 = true;
+		}(),
+		[&]() -> task<>
+		{
+			co_await latch;
+			after3 = true;
+		}(),
+		[&]() -> task<>
+		{
+			CHECK(!after1);
+			CHECK(!after2);
+			CHECK(!after3);
+			latch.count_down();
+			CHECK(!after1);
+			CHECK(!after2);
+			CHECK(!after3);
+			latch.count_down();
+			CHECK(after1);
+			CHECK(after2);
+			CHECK(after3);
+			co_return;
+		}()));
+}
+
+TEST_SUITE_END();