Regarding assertion with array in JSON format

Hello NehaLadani 

Here is a code sample for you.  Your output json was not syntactically correct when dropped into a json editor (https://jsoneditoronline.org), so I took the liberty to adjust it a little bit so that a code sample could be created...  I don't know assert requirements, so I just added a few to display what they might look like.

import groovy.json.JsonSlurper;

log.info 'Test Step "' + testRunner.runContext.currentStep.name + '" start...';
log.info "";

def String jsonStr = """
{
  "step_list": [
    {
      "end_date": "2035-09-01T00:00:00",
      "payments": 12,
      "sequence": 1
    },
    {
      "end_date": "2035-09-01T00:00:00",
      "payments": 67,
      "sequence": 2
    }
  ]
}
""";

def jsonSlurper = new JsonSlurper();
def jsonObj = jsonSlurper.parseText(jsonStr);  
log.info "jsonObj=$jsonObj";

def expectedSize = 2;
assert jsonObj.step_list.size() == expectedSize, "Expected step_list size to be $expectedSize but it is = ${jsonObj.step_list.size()}";

log.info "jsonObj.step_list.first()=${jsonObj.step_list.first()}";
log.info "jsonObj.step_list.last()=${jsonObj.step_list.last()}";

def datePattern = "yyyy-MM-dd";
jsonObj.step_list.each { step ->
   log.info "";
   log.info "step=${step}";

   def stepDate = Date.parse(datePattern, step.end_date);
   log.info "stepDate=${stepDate}";

   Date lowDate = new Date("08/15/2020");
   Date highDate = new Date("10/15/2040");
   def nowDate = new Date();
   assert stepDate > lowDate, "Expected the step date to be greater than $lowDate but it is $stepDate";
   assert stepDate < highDate, "Expected the step date to be less than $highDate but it is $stepDate";
   assert stepDate > nowDate, "Expected the step date to be greater than today but it is $stepDate";

   def expectedPaymentMinimum = 10;
   assert step.payments > expectedPaymentMinimum , "Expected the step payments to be greater than $expectedPaymentMinimum but it is ${step.payments}";
   
   if (step == jsonObj.step_list.first()) {
      log.info "step.sequence=${step.sequence}";
      def expectedFirstSequence = 1;
      assert step.sequence == expectedFirstSequence, "Expected the first step sequence to be $expectedFirstSequence but it is = ${step.sequence}";
   };
   if (step == jsonObj.step_list.last()) {
      log.info "step.sequence=${step.sequence}";
      def expectedLastSequence = 2;
      assert step.sequence == expectedLastSequence, "Expected the last step sequence to be $expectedLastSequence but it is = ${step.sequence}";
   };
};

log.info "";
log.info 'Test Step "' + testRunner.runContext.currentStep.name + '" done...';

Regards,

Todd