MUnit JSON Assertion

For a REST API in Mule which returns a JSON response, it is always advisable to write MUnit tests and assert the entire JSON response payload to avoid contract conflicts/mismatches. MUnit does not have any out-of-the-box component to compare two JSON files. In this example, we are using a Groovy script for this comparison/assertion.

Objective

Our objective is loading expected JSON data from a file and comparing it with actual MUnit payload which we got from the tested flow.

Steps

1. Create a Mule project using Anypoint Studio.

2. Create a flow called Flow1 with an HTTP inbound endpoint and set a JSON payload to send back as a response.

3. Create an MUnit test case for the above flow.

4. Inside test/resources, create a JSON file (expectedOutcome.json) which holds the expected JSON payload.

5. In your MUnit TestCase, add a flow ref to call Flow1.

6. After the flow ref, create a variable and load the expected json data from the file using the following MEL: #[getResource('expectedOutcome.json').asString()] 

7. Now, in your MUnit test case, drag and drop a Groovy component after the flow-ref.

8. Add the following script to the Groovy component: def map1 = new groovy.json.JsonSlurper().parseText(payload)def map2 = new groovy.json.JsonSlurper().parseText(flowVars.expectedOutcome)assert map1 == map2

9. Run your MUnit test; it will return a Test Case success if both JSON files/data are identical.

Refer to the code below for the full Flow and MUnit code.

Flow:

    <flow name="Flow1">
        <http:listener config-ref="HTTP_Listener_Configuration" path="/" doc:name="HTTP"/>
        <dw:transform-message doc:name="Transform Message">
            <dw:set-payload><![CDATA[%dw 1.0
%output application/json
---
{
"test":{
"data":{
"name":"dk",
"age":"26"
}
}
}]]></dw:set-payload>
        </dw:transform-message>
    </flow>

MUnit Test Case:

<?xml version="1.0" encoding="UTF-8"?>

<mule xmlns:scripting="http://www.mulesoft.org/schema/mule/scripting" xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation" xmlns:munit="http://www.mulesoft.org/schema/mule/munit" xmlns:spring="http://www.springframework.org/schema/beans" xmlns:core="http://www.mulesoft.org/schema/mule/core" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.mulesoft.org/schema/mule/munit http://www.mulesoft.org/schema/mule/munit/current/mule-munit.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-current.xsd
http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
http://www.mulesoft.org/schema/mule/scripting http://www.mulesoft.org/schema/mule/scripting/current/mule-scripting.xsd">
    <munit:config name="munit" doc:name="MUnit configuration" mock-connectors="false" mock-inbounds="false"/>
    <spring:beans>
        <spring:import resource="classpath:testbatch.xml"/>
    </spring:beans>
    <munit:test name="testbatch-test-suite-Flow1Test" description="Test">
        <flow-ref name="Flow1" doc:name="Flow-ref to Flow1"/>
        <set-variable variableName="expectedOutcome " value="#[getResource('expectedOutcome.json').asString()]" doc:name="set expectedOutcome Variable"/>
        <scripting:transformer doc:name="Groovy">
            <scripting:script engine="Groovy"><![CDATA[def map1 = new groovy.json.JsonSlurper().parseText(payload)
def map2 = new groovy.json.JsonSlurper().parseText(flowVars.expectedOutcome)

assert map1 == map2]]></scripting:script>
        </scripting:transformer>
    </munit:test>
</mule>

Expected outcome file:

{
  "test": {
    "data": {
      "name": "dk",
      "age": "26"
    }
  }
}