test: clean up gRPC channels after each test

build.gradle

@@ -181,6 +181,7 @@ configurations {
 dependencies {
   intTestImplementation "junit:junit:4.13.2"
     intTestImplementation "org.assertj:assertj-core:3.27.7"
+    intTestImplementation "io.grpc:grpc-testing:${grpcVersion}"
 }
 
 tasks.register('integrationTest', Test) {

src/intTest/java/TestClient.java

@@ -4,6 +4,7 @@
 import com.authzed.grpcutil.BearerToken;
 import io.grpc.ManagedChannel;
 import io.grpc.ManagedChannelBuilder;
+import io.grpc.testing.GrpcCleanupRule;
 
 import java.util.Random;
 
@@ -14,8 +15,11 @@ public class TestClient {
     public PermissionsServiceGrpc.PermissionsServiceBlockingStub permissionsService;
     public PermissionsServiceGrpc.PermissionsServiceStub asyncPermissionsService;
     public ExperimentalServiceGrpc.ExperimentalServiceBlockingStub experimentalService;
-    public TestClient() {
-        ManagedChannel channel = ManagedChannelBuilder.forTarget("localhost:50051").usePlaintext().build();
+    public TestClient(GrpcCleanupRule cleanupRule) {
+        // Registering the channel guarantees it is shut down when the test finishes:
+        // https://grpc.io/blog/graceful-cleanup-junit-tests/
+        ManagedChannel channel = cleanupRule.register(
+                ManagedChannelBuilder.forTarget("localhost:50051").usePlaintext().build());
         String token = generateToken();
         schemaService = SchemaServiceGrpc.newBlockingStub(channel)
                 .withCallCredentials(new BearerToken(token));

src/intTest/java/V1ClientTest.java

@@ -8,6 +8,8 @@
 import com.authzed.api.v1.*;
 
 import io.grpc.stub.StreamObserver;
+import io.grpc.testing.GrpcCleanupRule;
+import org.junit.Rule;
 import org.junit.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -20,10 +22,13 @@
 public class V1ClientTest {
     private static final Consistency fullyConsistent = Consistency.newBuilder().setFullyConsistent(true).build();
 
+    @Rule
+    public final GrpcCleanupRule grpcCleanup = new GrpcCleanupRule();
+
     @Test
     public void testBasicSchema() {
         // Initialize services
-        TestClient client = new TestClient();
+        TestClient client = new TestClient(grpcCleanup);
         String schema = "definition document {\n"
                 + "relation reader: user\n"
                 + "}\n"
@@ -40,15 +45,15 @@ public void testBasicSchema() {
 
     @Test
     public void testSchemaWithCaveats() {
-        TestClient client = new TestClient();
+        TestClient client = new TestClient(grpcCleanup);
         writeTestSchema(client);
     }
 
     // For an example with flow control, see
     // https://github.com/grpc/grpc-java/blob/9071c1ad7c842f4e73b6ae95b71f11c517b177a4/examples/src/main/java/io/grpc/examples/manualflowcontrol/ManualFlowControlClient.java
     @Test
     public void testCheck() {
-        TestClient client = new TestClient();
+        TestClient client = new TestClient(grpcCleanup);
         writeTestSchema(client);
         TestTuples testTuples = writeTestTuples(client);
 
@@ -87,7 +92,7 @@ public void testCheck() {
 
     @Test
     public void testCaveatedCheck() {
-        TestClient client = new TestClient();
+        TestClient client = new TestClient(grpcCleanup);
         writeTestSchema(client);
         TestTuples testTuples = writeTestTuples(client);
 
@@ -126,7 +131,7 @@ public void testCaveatedCheck() {
 
     @Test
     public void testLookupResources() {
-        TestClient client = new TestClient();
+        TestClient client = new TestClient(grpcCleanup);
         writeTestSchema(client);
         TestTuples testTuples = writeTestTuples(client);
 
@@ -148,7 +153,7 @@ public void testLookupResources() {
 
     @Test
     public void testLookupSubjects() {
-        TestClient client = new TestClient();
+        TestClient client = new TestClient(grpcCleanup);
         writeTestSchema(client);
         TestTuples testTuples = writeTestTuples(client);
 
@@ -171,7 +176,7 @@ public void testLookupSubjects() {
 
     @Test
     public void testCheckBulkPermissions() {
-        TestClient client = new TestClient();
+        TestClient client = new TestClient(grpcCleanup);
         writeTestSchema(client);
         TestTuples testTuples = writeTestTuples(client);
 
@@ -195,7 +200,7 @@ public void testCheckBulkPermissions() {
 
     @Test
     public void testBulkImport() throws InterruptedException {
-        TestClient client = new TestClient();
+        TestClient client = new TestClient(grpcCleanup);
         writeTestSchema(client);
         writeTestTuples(client);
 
@@ -212,7 +217,7 @@ public void testBulkImport() throws InterruptedException {
 
         // Note that this has a different preshared key
         // Validate import
-        TestClient emptyClient = new TestClient();
+        TestClient emptyClient = new TestClient(grpcCleanup);
         writeTestSchema(emptyClient);
 
         final CountDownLatch done = new CountDownLatch(1);