Mocha无法找到我动态生成的测试？

Question

While generating the tests using a for loop the dynamic tests are detected in the framework. But for one specific suite I need to fetch data from database and create tests based on that. The program that I am using is as follows

 describe("Testing existence of elements", function (existence_suite_done) {

    let elements = [];
    models.cypher('match (a:page {id: "74ab8f9d-e24b-41d1-9390-d6fb338ece38"})-[r:child]->(b:element) return b;')
      .then((data) => {
        elements = data.records;
      })
      .then(() => {
        for(var i=0;i<elements.length;i++) {
          it('hello', (done) => {
            done();
          });
        }
      })
      .then(existence_suite_done)
      .catch(existence_suite_done);
  });

Now I am curious how to get that suite working specifically when the tests are dependent on results from a promise. I imagine it has something to do with scopes but am unable to figure out where I am going wrong. Any help is appreciated

Answer 1

This should work.

// Your async data fetching emulation.
var models = {
    cypher: () => {
        return new Promise((resolve, reject) => {
            setTimeout(function () {
                resolve({ records: ['A', 'B', 'C', 'D', 'E'] });
            }, 300);
        });
    }
};


// The data query is inverted with respect to the loop.
describe("Testing existence of elements", function () {
    let elements;

    it('Fething and testing data', () => {
        return models.cypher()
            .then((data) => {
                elements = data.records;
            })
            .then(() => {
                for (var i = 0; i < elements.length; i++) {
                    var el = elements[i];
                    console.log(`Testing ${el} ...`);
                }
            });
    });
});

Alternately, instead of using the done() callback , you may return a Promise ( docs ).

PS

It seems that Mocha does look for tests only within the describe's suite function. So, it won't be waiting for your data fetching async callback to look into it.

Here I found a similar question .