I use jasmine runs and wait to test asynchronous operations. Everything works fine but I'm not quite sure what goes on behind the scenes.

The jasmine documentation states the following example to which I added three log statement.

describe(Asynchronous specs, function() {

  var value, flag;



  it(should support async execution of test preparation and exepectations, function() {



    runs(function() {

      flag = false;

      value = 0;



      setTimeout(function() {

        flag = true;

      }, 500);

    });



    waitsFor(function() {

      value++;

      if(flag) {

          console.log(A);

      }

      return flag;

    }, The Value should be incremented, 750);



    console.log(B);



    runs(function() {

      console.log(C);

      expect(value).toBeGreaterThan(0);

    });

  });

});

});

The first runs and waitsFor are perfectly clear to me. Runs starts an asynchronous operation and waitsFor waits for a condition.

However I do not understand why the second runs does not start until the waitsFor is finished. The waitsFor is not a blocking call.

My guess is that waitsFor implicitly blocks any following runs call until it is finished. Is this so?

My evidence is that the console.log statements output:

B A C

But if waitsFor would really block it should be

A B C