[command] Add NetworkButton (#2373)

Closes #2371

wpilibNewCommands/src/test/native/cpp/frc2/command/button/NetworkButtonTest.cpp

@@ -0,0 +1,46 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2020 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include <networktables/NetworkTableInstance.h>
+
+#include "../CommandTestBase.h"
+#include "frc2/command/CommandScheduler.h"
+#include "frc2/command/RunCommand.h"
+#include "frc2/command/WaitUntilCommand.h"
+#include "frc2/command/button/NetworkButton.h"
+#include "gtest/gtest.h"
+
+using namespace frc2;
+
+class NetworkButtonTest : public CommandTestBase {
+  void SetUp() override { nt::NetworkTableInstance::GetDefault().StartLocal(); }
+
+  void TearDown() override {
+    nt::NetworkTableInstance::GetDefault().DeleteAllEntries();
+    nt::NetworkTableInstance::GetDefault().StopLocal();
+  }
+};
+
+TEST_F(NetworkButtonTest, SetNetworkButtonTest) {
+  auto& scheduler = CommandScheduler::GetInstance();
+  auto entry = nt::NetworkTableInstance::GetDefault()
+                   .GetTable("TestTable")
+                   ->GetEntry("Test");
+  bool finished = false;
+
+  WaitUntilCommand command([&finished] { return finished; });
+
+  NetworkButton("TestTable", "Test").WhenActive(&command);
+  scheduler.Run();
+  EXPECT_FALSE(scheduler.IsScheduled(&command));
+  entry.SetBoolean(true);
+  scheduler.Run();
+  EXPECT_TRUE(scheduler.IsScheduled(&command));
+  finished = true;
+  scheduler.Run();
+  EXPECT_FALSE(scheduler.IsScheduled(&command));
+}