[command] Add NetworkButton (#2373)

Closes #2371

wpilibNewCommands/src/test/java/edu/wpi/first/wpilibj2/command/button/NetworkButtonTest.java

@@ -0,0 +1,52 @@
+/*----------------------------------------------------------------------------*/
+/* 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+package edu.wpi.first.wpilibj2.command.button;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import edu.wpi.first.networktables.NetworkTableInstance;
+import edu.wpi.first.wpilibj2.command.CommandScheduler;
+import edu.wpi.first.wpilibj2.command.CommandTestBase;
+
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+
+class NetworkButtonTest extends CommandTestBase {
+  @BeforeEach
+  void setup() {
+    NetworkTableInstance.getDefault().startLocal();
+  }
+
+  @AfterEach
+  void teardown() {
+    NetworkTableInstance.getDefault().deleteAllEntries();
+    NetworkTableInstance.getDefault().stopLocal();
+  }
+
+  @Test
+  void setNetworkButtonTest() {
+    var scheduler = CommandScheduler.getInstance();
+    var commandHolder = new MockCommandHolder(true);
+    var command = commandHolder.getMock();
+    var entry = NetworkTableInstance.getDefault()
+        .getTable("TestTable")
+        .getEntry("Test");
+
+    var button = new NetworkButton("TestTable", "Test");
+    entry.setBoolean(false);
+    button.whenPressed(command);
+    scheduler.run();
+    verify(command, never()).schedule(true);
+    entry.setBoolean(true);
+    scheduler.run();
+    scheduler.run();
+    verify(command).schedule(true);
+  }
+}