chore: Add Showcase Callables IT

showcase/gapic-showcase/pom.xml

@@ -165,7 +165,6 @@
       <artifactId>junit</artifactId>
       <scope>test</scope>
     </dependency>
-
     <dependency>
       <groupId>com.google.truth</groupId>
       <artifactId>truth</artifactId>

showcase/gapic-showcase/src/test/java/com/google/showcase/v1beta1/it/ITUnaryCallable.java

@@ -100,11 +100,30 @@ public void testGrpc_shutdown() {
   }
 
   @Test
-  public void testHttpJson() {
+  public void testHttpJson_receiveContent() {
     assertThat(echoHttpJson("http-echo?")).isEqualTo("http-echo?");
     assertThat(echoHttpJson("http-echo!")).isEqualTo("http-echo!");
   }
 
+  @Test
+  public void testHttpJson_serverResponseError_throwsException() {
+    StatusCode.Code cancelledStatusCode = StatusCode.Code.CANCELLED;
+    EchoRequest requestWithServerError =
+        EchoRequest.newBuilder()
+            .setError(Status.newBuilder().setCode(cancelledStatusCode.ordinal()).build())
+            .build();
+    CancelledException exception =
+        assertThrows(CancelledException.class, () -> httpJsonClient.echo(requestWithServerError));
+    assertThat(exception.getStatusCode().getCode()).isEqualTo(cancelledStatusCode);
+  }
+
+  @Test
+  public void testHttpJson_shutdown() {
+    assertThat(httpJsonClient.isShutdown()).isFalse();
+    httpJsonClient.shutdown();
+    assertThat(httpJsonClient.isShutdown()).isTrue();
+  }
+
   private String echoGrpc(String value) {
     EchoResponse response = grpcClient.echo(EchoRequest.newBuilder().setContent(value).build());
     return response.getContent();