const dataArray = [['Data 3', 'd3'], ['Data 4', 'd4']];
dataArray.forEach(row => {
  describe('Test group using %s with tag %s', () => 
  {
    let groupData = [{'id':'01'},{'id':'02'}];
    let groupTag = '';
    let datafile = '';
    switch(row[1])
    {
    case 'd3': groupData = [{'id':'31'},{'id':'32'}]; break;
    case 'd4': groupData = [{'id':'41'},{'id':'42'}]; break;
    }
    datafile = row[0];
    groupTag = row[1];
    console.log('Beginning tests for '+groupTag+' using '+datafile+'\r\n groupData set to '+JSON.stringify(groupData[0])+' and '+JSON.stringify(groupData[1]));
    groupData.forEach(num => test('Test case ${num} [tag:sandbox]', () => 
      {
        console.log(groupTag+' - Running test '+num.id); 
        expect(num.id).toBeDefined(); //example test
      }));
  });
});
 

This got the 'desired' result, defining all the tests first, then running them

    console.log
      Beginning tests for d3 using Data 3
       groupData set to {"id":"31"} and {"id":"32"}
      Beginning tests for d4 using Data 4
       groupData set to {"id":"41"} and {"id":"42"}
      d3 - Running test 31
      d3 - Running test 32
      d4 - Running test 41
      d4 - Running test 42

hat tip to the linked question Using jest's test.each vs. looping with forEach
and https://stackoverflow.com/users/3001761/jonrsharpe for his comment.