casperjs error traceback

gistfile1.js

TEST
-----

// googletesting.js
casper.test.begin('Google search retrieves 10 or more results', 5, function suite(test) {
    casper.start("http://www.google.fr/", function() {
        test.assertTitle("Google", "google homepage title is the one expected");
        test.assertExists('form[action="/yahoo"]', "main form is found");
        this.fill('form[action="/search"]', {
            q: "casperjs"
        }, true);
    });

    casper.then(function() {
        test.assertTitle("casperjs - Recherche Google", "google title is ok");
        test.assertUrlMatch(/q=casperjs/, "search term has been submitted");
        test.assertEval(function() {
            return __utils__.findAll("h3.r").length >= 10;
        }, "google search for \"casperjs\" retrieves 10 or more results");
    });

    casper.run(function() {
        test.done();
    });
});


RESULT
--------

~ casperjs test google.js
Test file: google.js                                                            
# Google search retrieves 10 or more results
PASS google homepage title is the one expected
FAIL main form is found
#    type: assertExists
#    file: google.js:5
#    code: test.assertExists('form[action="/yahoo"]', "main form is found");
#    subject: false
#    selector: "form[action=\"/yahoo\"]"
⚠  looks like you did not use begin(), which is mandatory since 1.1
FAIL AssertionError: main form is found
#    type: error
#    file: google.js
#    subject: false
#    error: {"message":"main form is found","name":"AssertionError","result":{"success":false,"type":"assertExists","standard":"Found an element matching: form[action=\"/yahoo\"]","message":"main form is found","file":"google.js","doThrow":true,"values":{"subject":false,"selector":"form[action=\"/yahoo\"]"},"line":5,"lineContents":"test.assertExists('form[action=\"/yahoo\"]', \"main form is found\");","suite":"Google search retrieves 10 or more results","time":1},"line":301,"sourceId":139995371313280,"sourceURL":"/home/ebr/bin/casperjs/modules/tester.js","stack":"AssertionError: main form is found\n    at assert (/home/ebr/bin/casperjs/modules/tester.js:301)\n    at assertExists (/home/ebr/bin/casperjs/modules/tester.js:493)\n    at google.js:5\n    at runStep (/home/ebr/bin/casperjs/modules/casper.js:1525)\n    at checkStep (/home/ebr/bin/casperjs/modules/casper.js:368)","stackArray":[{"function":"assert","sourceURL":"/home/ebr/bin/casperjs/modules/tester.js","line":301},{"function":"assertExists","sourceURL":"/home/ebr/bin/casperjs/modules/tester.js","line":493},{"sourceURL":"google.js","line":5},{"function":"runStep","sourceURL":"/home/ebr/bin/casperjs/modules/casper.js","line":1525},{"function":"checkStep","sourceURL":"/home/ebr/bin/casperjs/modules/casper.js","line":368}]}
FAIL 3 tests executed in 1.344s, 1 passed, 2 failed, 0 dubious, 0 skipped.      

Details for the 2 failed tests:

In google.js:5
  Google search retrieves 10 or more results
    assertExists: main form is found
In google.js
  Google search retrieves 10 or more results
    error: AssertionError: main form is found