@Test
    void testUnlimitedRequest() throws Exception {
        final ClientRequestContext ctx = newContext();
        final HttpRequest req = newReq();
        final HttpResponseWriter actualRes = HttpResponse.streaming();

        when(delegate.execute(ctx, req)).thenReturn(actualRes);

        final ConcurrencyLimitingClient client =
                newDecorator(1).apply(delegate);

        // A request should be delegated immediately, creating no deferred response.
        final HttpResponse res = client.execute(ctx, req);
        await().untilAsserted(() -> verify(delegate).execute(ctx, req));
        assertThat(res.isOpen()).isTrue();
        assertThat(client.numActiveRequests()).isEqualTo(1);

        // Complete the response, leaving no active requests.
        closeAndDrain(actualRes, res);
        await().untilAsserted(() -> assertThat(client.numActiveRequests()).isZero());
    }
Tests the case where a delegate raises an exception rather than returning a response.
core/src/test/java/com/linecorp/armeria/client/limit/ConcurrencyLimitingClientTest.java