Varioius IsolatedNetworkTablesExtension fixes

lib/src/test/java/com/team2813/lib2813/preferences/IsolatedPreferences.java

@@ -42,12 +42,12 @@ protected void before() {
 
   @Override
   protected void after() {
-    if (!tempInstance.waitForListenerQueue(.4)) {
+    Preferences.setNetworkTableInstance(NetworkTableInstance.getDefault());
+    if (!tempInstance.waitForListenerQueue(.2)) {
       System.err.println(
           "Timed out waiting for the NetworkTableInstance listener queue to empty (waited 200ms);"
               + " JVM may crash");
     }
-    Preferences.setNetworkTableInstance(NetworkTableInstance.getDefault());
     tempInstance.close();
   }
 }

testing/src/main/java/com/team2813/lib2813/testing/junit/jupiter/IsolatedNetworkTablesExtension.java

@@ -18,6 +18,7 @@
 import edu.wpi.first.networktables.NetworkTableInstance;
 import edu.wpi.first.wpilibj.Preferences;
 import org.junit.jupiter.api.extension.AfterEachCallback;
+import org.junit.jupiter.api.extension.BeforeEachCallback;
 import org.junit.jupiter.api.extension.Extension;
 import org.junit.jupiter.api.extension.ExtensionContext;
 import org.junit.jupiter.api.extension.ExtensionContext.Namespace;
@@ -45,53 +46,64 @@
  * @since 2.0.0
  */
 public final class IsolatedNetworkTablesExtension
-    implements Extension, AfterEachCallback, ParameterResolver {
-  private static final StoreKey<NetworkTableInstance> NETWORK_TABLE_INSTANCE_KEY =
-      StoreKey.of(NetworkTableInstance.class);
+    implements Extension, BeforeEachCallback, AfterEachCallback, ParameterResolver {
+  private static final Namespace NAMESPACE = Namespace.create(IsolatedNetworkTablesExtension.class);
+  private static final StoreKey<Data> DATA_KEY = StoreKey.of(Data.class);
+
+  @Override
+  public void beforeEach(ExtensionContext context) {
+    Store store = context.getStore(NAMESPACE);
+    NetworkTableInstance ntInstance =
+        DATA_KEY.getOrComputeIfAbsent(store, Data::create).testInstance;
+    Preferences.setNetworkTableInstance(ntInstance);
+  }
 
   @Override
   public void afterEach(ExtensionContext context) {
     // If this extension created a temporary NetworkTableInstance, close it.
-    var ntInstance = NETWORK_TABLE_INSTANCE_KEY.remove(getStore(context));
-    if (ntInstance != null) {
+    Store store = context.getStore(NAMESPACE);
+    Data data = DATA_KEY.remove(store);
+    if (data != null) {
+      Preferences.setNetworkTableInstance(data.prevInstance);
+
       // Clear out the listener queue before destroying our temporary NetworkTableInstance.
       //
       // This works around a race condition in WPILib where a listener registered by Preferences can
       // be called after the NetworkTableInstance was closed (see
       // https://github.com/wpilibsuite/allwpilib/issues/8215).
-      if (!ntInstance.waitForListenerQueue(.4)) {
+      if (!data.testInstance.waitForListenerQueue(.2)) {
         System.err.println(
             "Timed out waiting for the NetworkTableInstance listener queue to empty (waited 200ms);"
                 + " JVM may crash");
       }
-
-      Preferences.setNetworkTableInstance(NetworkTableInstance.getDefault());
-      ntInstance.close();
+      data.testInstance.close();
     }
   }
 
   @Override
   public boolean supportsParameter(
       ParameterContext parameterContext, ExtensionContext extensionContext)
       throws ParameterResolutionException {
+    if (parameterContext.getTarget().isEmpty()) {
+      return false; // The extension only supports test method parameter injection.
+    }
     return NetworkTableInstance.class.equals(parameterContext.getParameter().getType());
   }
 
   @Override
   public NetworkTableInstance resolveParameter(
       ParameterContext parameterContext, ExtensionContext extensionContext)
       throws ParameterResolutionException {
-    Store store = getStore(extensionContext);
-    NetworkTableInstance ntInstance =
-        NETWORK_TABLE_INSTANCE_KEY.getOrComputeIfAbsent(store, NetworkTableInstance::create);
-
-    ntInstance.startLocal();
-    Preferences.setNetworkTableInstance(ntInstance);
-    return ntInstance;
+    Store store = extensionContext.getStore(NAMESPACE);
+    return DATA_KEY.get(store).testInstance;
   }
 
-  /** Gets the {@link Store} for this extension. */
-  private Store getStore(ExtensionContext context) {
-    return context.getStore(Namespace.create(getClass(), context.getRequiredTestMethod()));
+  private record Data(NetworkTableInstance testInstance, NetworkTableInstance prevInstance) {
+    static Data create() {
+      NetworkTableInstance testInstance = NetworkTableInstance.create();
+      testInstance.startLocal();
+      NetworkTableInstance prevInstance = Preferences.getNetworkTable().getInstance();
+      return new Data(testInstance, prevInstance);
+    }
   }
 }

testing/src/test/java/com/team2813/lib2813/testing/junit/jupiter/IsolatedNetworkTablesExtensionTest.java

@@ -1,5 +1,5 @@
 /*
-Copyright 2025 Prospect Robotics SWENext Club
+Copyright 2025-2026 Prospect Robotics SWENext Club
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -20,6 +20,7 @@
 import static org.junit.platform.engine.discovery.DiscoverySelectors.selectClass;
 
 import edu.wpi.first.networktables.NetworkTableInstance;
+import edu.wpi.first.wpilibj.Preferences;
 import org.junit.jupiter.api.MethodOrderer;
 import org.junit.jupiter.api.Tag;
 import org.junit.jupiter.api.Test;
@@ -42,6 +43,12 @@ public void verifyProvidesNetworkTableParameter(NetworkTableInstance ntInstance)
       assertThat(ntInstance.getHandle())
           .isNotEqualTo(NetworkTableInstance.getDefault().getHandle());
     }
+
+    @Test
+    public void verifyReplacesPreferencesNetworkTableInstance() {
+      assertThat(Preferences.getNetworkTable().getInstance().getHandle())
+          .isNotEqualTo(NetworkTableInstance.getDefault().getHandle());
+    }
   } // end SampleTest
 
   @Test