I'm only getting 14% coverage with the test method below, any advise?

Visualforce page:

<apex:page controller="CustomPage" showHeader="true" >
<table>
<tr>
<td>
<apex:dataTable value="{!List}" var="r">
<apex:column value="{!r.Name}"/>
</apex:dataTable>
</td>
</tr>
</apex:page>

Controller:

public class IngList {
  // ApexPages.StandardSetController must be instantiated  
    
  // for standard list controllers  
    
    public ApexPages.StandardSetController setCon {
        get {
            if(setCon == null) {
                setCon = new ApexPages.StandardSetController(Database.getQueryLocator(
                      [select name, from CustomObject__c WHERE custom_check_box_field__c = true]));
            }
            return setCon;
        }
        set;
    }

    // Initialize setCon and return a list of records  
    
    public List<CustomObject__c> getList() {
         return (List<CustomObject__c>) setCon.getRecords();
    }
}

Test Class:

@isTest

private class TestIngList {

static testMethod void testIngList(){
    ApexPages.StandardSetController setCon;
    PageReference pageRef = Page.CustomPage;

Custom_Object__c cusobj = new Custom_Object__c();
cusobj.custom_check_box_field__c = true;
insert cusobj;

List<CustomObject__c> cus = new List<Custom_Object__c>{};

System.assertNotEquals(null, cusobj.Id);
    Test.setCurrentPage(pageRef);
    IngList controller = new IngList();

}
}

Thanks in Advance!