Add tests for SendableChooser and Command Sendable functionality (#5179)

wpilibj/src/test/java/edu/wpi/first/wpilibj/smartdashboard/SendableChooserTest.java

@@ -0,0 +1,72 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+package edu.wpi.first.wpilibj.smartdashboard;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+import edu.wpi.first.networktables.NetworkTableInstance;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+class SendableChooserTest {
+  private NetworkTableInstance m_inst;
+
+  @BeforeEach
+  void setUp() {
+    m_inst = NetworkTableInstance.create();
+    SmartDashboard.setNetworkTableInstance(m_inst);
+  }
+
+  @ValueSource(ints = {0, 1, 2, 3})
+  @ParameterizedTest
+  void returnsSelected(int toSelect) {
+    try (var chooser = new SendableChooser<Integer>();
+        var publisher = m_inst.getStringTopic("/SmartDashboard/chooser/selected").publish()) {
+      for (int i = 1; i <= 3; i++) {
+        chooser.addOption(String.valueOf(i), i);
+      }
+      chooser.setDefaultOption(String.valueOf(0), 0);
+
+      SmartDashboard.putData("chooser", chooser);
+      SmartDashboard.updateValues();
+      publisher.set(String.valueOf(toSelect));
+      SmartDashboard.updateValues();
+      assertEquals(toSelect, chooser.getSelected());
+    }
+  }
+
+  @Test
+  void defaultIsReturnedOnNoSelect() {
+    try (var chooser = new SendableChooser<Integer>()) {
+      for (int i = 1; i <= 3; i++) {
+        chooser.addOption(String.valueOf(i), i);
+      }
+      chooser.setDefaultOption(String.valueOf(0), 0);
+
+      assertEquals(0, chooser.getSelected());
+    }
+  }
+
+  @Test
+  void nullIsReturnedOnNoSelectAndNoDefault() {
+    try (var chooser = new SendableChooser<Integer>()) {
+      for (int i = 1; i <= 3; i++) {
+        chooser.addOption(String.valueOf(i), i);
+      }
+
+      assertNull(chooser.getSelected());
+    }
+  }
+
+  @AfterEach
+  void tearDown() {
+    m_inst.close();
+    SmartDashboard.setNetworkTableInstance(NetworkTableInstance.getDefault());
+  }
+}