Add more than 200 test classes in the test suite

Question

I am trying to add test classes in the test suite.

But when I click on save, I am getting below error:

I am trying to add more test classes using Apex like below using Anonymous execution:

List<ApexClass> ac = [SELECT Id, Name, Body FROM ApexClass];
List<ApexClass> testClasses = new List<ApexClass>();
List<TestSuiteMembership > testSuiteMembership = new List<TestSuiteMembership>();
List<Id> existingApexClassInTestSuiteIdList = new List<Id>();
for( TestSuiteMembership testSuiteMembership : [SELECT ApexClassId FROM TestSuiteMembership WHERE ApexTestSuiteId ='<Test suite id>']){
    existingApexClassInTestSuiteIdList.add( testSuiteMembership.ApexClassId);
}
TestSuiteMembership testSuiteMembershipObject;
for(ApexClass a : ac){
    if(!existingApexClassInTestSuiteIdList.contains(a.Id) && (a.Body.containsIgnoreCase('@istest') || a.Body.contains('static testmethod'))){
        testSuiteMembershipObject = new TestSuiteMembership();
        testSuiteMembershipObject.ApexClassId = a.Id;
        testSuiteMembershipObject.ApexTestSuiteId = '<Test suite id>';
        testSuiteMembership.add( testSuiteMembershipObject);
    }
}
insert testSuiteMembership;

But not able to insert the objects and getting below error:

Alternative option: I can create multiple test suites and add 200 classes in each suite.

How can we add more than 200 test cases in single test suite?

Answer 1

To use the REST api for the insertions as the error message and Raul suggest, try replacing this:

insert testSuiteMembership

With this:

String baseURL = URL.getSalesforceBaseUrl().toExternalForm();
String endpoint = baseURL + '/services/data/v46.0/sobjects/TestSuiteMembership';      
HttpRequest req = new HttpRequest();
req.setEndpoint(endpoint); 
req.setMethod('POST'); 
req.setHeader('Content-Type', 'application/json;charset=UTF-8');
req.setHeader('Authorization', 'Bearer ' + UserInfo.getSessionID());  
req.setBody(json.serializePretty(testSuiteMembership));
Http http = new Http();   
HttpResponse res = http.send(req);  
System.debug('Response Code > ' + res.getStatusCode());
System.debug(' Response > ' + res.getBody());