Add ReceiverTest.

And fix a small bug with the Receiver not eating all the input.

src/ftxui/component/receiver_test.cpp

@@ -0,0 +1,70 @@
+#include "ftxui/component/receiver.hpp"
+
+#include <thread>
+
+#include "gtest/gtest.h"
+
+using namespace ftxui;
+
+TEST(Receiver, Basic) {
+  auto receiver = MakeReceiver<char>();
+  auto sender = receiver->MakeSender();
+
+  sender->Send('a');
+  sender->Send('b');
+  sender->Send('c');
+  sender.reset();
+
+  char a, b, c, d;
+  EXPECT_TRUE(receiver->Receive(&a));
+  EXPECT_TRUE(receiver->Receive(&b));
+  EXPECT_TRUE(receiver->Receive(&c));
+  EXPECT_FALSE(receiver->Receive(&d));
+
+  EXPECT_EQ(a, 'a');
+  EXPECT_EQ(b, 'b');
+  EXPECT_EQ(c, 'c');
+}
+
+TEST(Receiver, BasicWithThread) {
+  auto r1 = MakeReceiver<char>();
+  auto r2 = MakeReceiver<char>();
+  auto r3 = MakeReceiver<char>();
+
+  auto s1 = r1->MakeSender();
+  auto s2 = r2->MakeSender();
+  auto s3 = r3->MakeSender();
+
+  auto s1_bis = r1->MakeSender();
+
+  auto stream = [](Receiver<char> receiver, Sender<char> sender) {
+    char c;
+    while (receiver->Receive(&c))
+      sender->Send(c);
+  };
+
+  // Convert data from a different thread.
+  auto t12 = std::thread(stream, std::move(r1), std::move(s2));
+  auto t23 = std::thread(stream, std::move(r2), std::move(s3));
+
+  // Send some data.
+  s1->Send('1');
+  s1_bis->Send('2');
+  s1->Send('3');
+  s1_bis->Send('4');
+
+  // Close the stream.
+  s1.reset();
+  s1_bis.reset();
+
+  char c;
+  EXPECT_TRUE(r3->Receive(&c));EXPECT_EQ(c, '1');
+  EXPECT_TRUE(r3->Receive(&c)); EXPECT_EQ(c, '2');
+  EXPECT_TRUE(r3->Receive(&c)); EXPECT_EQ(c, '3');
+  EXPECT_TRUE(r3->Receive(&c)); EXPECT_EQ(c, '4');
+  EXPECT_FALSE(r3->Receive(&c));
+
+  // Thread will end at the end of the stream.
+  t12.join();
+  t23.join();
+}