MUnit test fails when mocking external REST API call

Question

I have the following Mule flow that is built to retrieve some details from an external API and then map this to some payload to return to the calling client:

<flow name="get:/clients/{clientId}:api-config">
<http:request config-ref="HTTPS_Request_Configuration" path="/api/clients/{clientId}" method="GET" host="host.com" port="443" doc:name="Find Client by ID">
    <http:request-builder>
        <http:uri-param paramName="clientId" value="#[flowVars['clientId']]"/>
    </http:request-builder>
    <http:success-status-code-validator values="0..599"/>
</http:request>
<logger message="#[payload]" level="INFO" doc:name="Logger"/>
...

I have created the following unit test where I mock the HTTP request using the MUnit mock processor:

<munit:test name="get:/clients/{clientId}:api-config-200-application/json-FlowTest" description="Verifying functionality of [get:/clients/{clientId}:api-config-200-application/json]">
<mock:when messageProcessor=".*:.*" doc:name="Mock">
    <mock:with-attributes>
        <mock:with-attribute name="doc:name" whereValue="#['Find Client by ID']"/>
    </mock:with-attributes>
    <mock:then-return payload="#[getResource('sample-client.json').asStream()]" mimeType="application/json"/>
</mock:when>
<set-variable variableName="clientId" value="#['null']" doc:name="clientId"/>
<http:request config-ref="HTTP_Request_Configuration" path="/clients/#[flowVars['clientId']]" method="GET" doc:name="HTTP"/>
<object-to-string-transformer doc:name="http response to string"/>
<munit:assert-true message="The HTTP Status code is not correct!" condition="#[messageInboundProperty('http.status').is(eq(200))]" doc:name="assert that - http.status eq 200"/>
<munit:assert-on-equals message="The response payload is not correct!" expectedValue="..."/>

I'm getting an unusual error when I try and run this test. It seems as if the test is failing due to an HTTP timeout. I don't understand how this is possible when the HTTP request processor is being mocked and therefore no external calls should be getting made?

The error message I'm seeing is as follows:

ERROR 2016-02-19 12:25:59,359 [main] org.mule.exception.DefaultMessagingExceptionStrategy: 
********************************************************************************
Message               : Error sending HTTP request. Message payload is of type: String
Code                  : MULE_ERROR--2
--------------------------------------------------------------------------------
Exception stack is:
1. Timeout exceeded (java.util.concurrent.TimeoutException)
  com.ning.http.client.providers.grizzly.GrizzlyAsyncHttpProvider:426 (null)
2. Error sending HTTP request. Message payload is of type: String (org.mule.api.MessagingException)
  org.mule.module.http.internal.request.DefaultHttpRequester:287 (http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/api/MessagingException.html)
--------------------------------------------------------------------------------
Root Exception stack trace:
java.util.concurrent.TimeoutException: Timeout exceeded
    at com.ning.http.client.providers.grizzly.GrizzlyAsyncHttpProvider.timeout(GrizzlyAsyncHttpProvider.java:426)
    at com.ning.http.client.providers.grizzly.GrizzlyAsyncHttpProvider$3.onTimeout(GrizzlyAsyncHttpProvider.java:274)
    at org.glassfish.grizzly.utils.IdleTimeoutFilter$DefaultWorker.doWork(IdleTimeoutFilter.java:398)
    + 3 more (set debug level logging or '-Dmule.verbose.exceptions=true' for everything)
********************************************************************************

Answer 1

In your test, why are you making call to http:endpoint here <http:request config-ref="HTTP_Request_Configuration" path="/clients/#[flowVars['clientId']]" method="GET" doc:name="HTTP"/>

ALso, I don't see a <flow-ref...> call to call your actual flow under test.

EDIT:

The basic test structure may follow this skeleton:

     <munit:config name="munit" doc:name="MUnit configuration"/>
        <spring:beans>
            <spring:import resource="classpath:munit-test.xml"/>
        </spring:beans>
        <munit:test name="new-test-suite-get:/clients/{clientId}:api-configTest" description="Test">

         <mock:when messageProcessor=".*:.*" doc:name="Mock">
                <mock:with-attributes>
                    <mock:with-attribute name="doc:name"
                        whereValue="#['Find Client by ID']" />
                </mock:with-attributes>
                <mock:then-return payload="#[getResource('sample-client.json').asStream()]"
                    mimeType="application/json" />
            </mock:when> 
            <set-variable variableName="clientId" value="#['null']"
                doc:name="clientId" />
<!-- Below will make an actual call to the flow -->
            <flow-ref name="get:/clients/{clientId}:api-config" doc:name="Flow-ref to get:/clients/{clientId}:api-config"/>
        </munit:test>