add tests

Author: rahul2393

google-cloud-spanner/src/test/java/com/google/cloud/spanner/spi/v1/GrpcChannelFinderServerFactoryTest.java

@@ -0,0 +1,119 @@
+/*
+ * Copyright 2026 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.cloud.spanner.spi.v1;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertThrows;
+
+import com.google.api.gax.grpc.InstantiatingGrpcChannelProvider;
+import com.google.cloud.spanner.SpannerException;
+import io.grpc.ManagedChannelBuilder;
+import org.junit.Test;
+
+public class GrpcChannelFinderServerFactoryTest {
+
+  private static InstantiatingGrpcChannelProvider createProvider(String endpoint) {
+    return InstantiatingGrpcChannelProvider.newBuilder()
+        .setEndpoint(endpoint)
+        .setChannelConfigurator(ManagedChannelBuilder::usePlaintext)
+        .build();
+  }
+
+  @Test
+  public void defaultServerIsCached() throws Exception {
+    GrpcChannelFinderServerFactory factory =
+        new GrpcChannelFinderServerFactory(createProvider("localhost:1234"));
+    try {
+      ChannelFinderServer defaultServer = factory.defaultServer();
+      ChannelFinderServer server = factory.create(defaultServer.getAddress());
+      assertThat(server).isSameInstanceAs(defaultServer);
+    } finally {
+      factory.shutdown();
+    }
+  }
+
+  @Test
+  public void createCachesPerAddress() throws Exception {
+    GrpcChannelFinderServerFactory factory =
+        new GrpcChannelFinderServerFactory(createProvider("localhost:1234"));
+    try {
+      ChannelFinderServer first = factory.create("localhost:1111");
+      ChannelFinderServer second = factory.create("localhost:1111");
+      ChannelFinderServer third = factory.create("localhost:2222");
+
+      assertThat(second).isSameInstanceAs(first);
+      assertThat(third).isNotSameInstanceAs(first);
+    } finally {
+      factory.shutdown();
+    }
+  }
+
+  @Test
+  public void evictRemovesNonDefaultServer() throws Exception {
+    GrpcChannelFinderServerFactory factory =
+        new GrpcChannelFinderServerFactory(createProvider("localhost:1234"));
+    try {
+      ChannelFinderServer first = factory.create("localhost:1111");
+      factory.evict("localhost:1111");
+      ChannelFinderServer second = factory.create("localhost:1111");
+
+      assertThat(second).isNotSameInstanceAs(first);
+    } finally {
+      factory.shutdown();
+    }
+  }
+
+  @Test
+  public void evictIgnoresDefaultServer() throws Exception {
+    GrpcChannelFinderServerFactory factory =
+        new GrpcChannelFinderServerFactory(createProvider("localhost:1234"));
+    try {
+      ChannelFinderServer defaultServer = factory.defaultServer();
+      factory.evict(defaultServer.getAddress());
+      ChannelFinderServer server = factory.create(defaultServer.getAddress());
+
+      assertThat(server).isSameInstanceAs(defaultServer);
+    } finally {
+      factory.shutdown();
+    }
+  }
+
+  @Test
+  public void shutdownPreventsNewServers() throws Exception {
+    GrpcChannelFinderServerFactory factory =
+        new GrpcChannelFinderServerFactory(createProvider("localhost:1234"));
+    factory.shutdown();
+
+    assertThrows(SpannerException.class, () -> factory.create("localhost:1111"));
+    assertThat(factory.defaultServer().getChannel().isShutdown()).isTrue();
+  }
+
+  @Test
+  public void healthReflectsChannelShutdown() throws Exception {
+    GrpcChannelFinderServerFactory factory =
+        new GrpcChannelFinderServerFactory(createProvider("localhost:1234"));
+    try {
+      ChannelFinderServer server = factory.create("localhost:1111");
+      assertThat(server.isHealthy()).isTrue();
+
+      server.getChannel().shutdownNow();
+      assertThat(server.isHealthy()).isFalse();
+    } finally {
+      factory.shutdown();
+    }
+  }
+}