Mastering JavaScript

Testing and Debugging
• toContain(): This checks whether an element is part of an array. This is not
an exact object match as toBe(). For example, look at the following code:
expect([1, 2, 3]).toContain(3);
expect("astronomy is a science").toContain("science");
• toBeDefined() and toBeUndefined(): These two matches are handy to
check whether a variable is undefined (or not).
• toBeNull(): This checks whether a variable's value is null.
• toBeGreaterThan() and toBeLessThan(): These matchers perform numeric
comparisons (they work on strings too):
expect(2).toBeGreaterThan(1);
expect(1).toBeLessThan(2);
expect("a").toBeLessThan("b");
One interesting feature of Jasmine is the spies. When you are writing a large system,
it is not possible to make sure that all systems are always available and correct. At
the same time, you don't want your unit tests to fail due to a dependency that may be
broken or unavailable. To simulate a situation where all dependencies are available
for a unit of code that we want to test, we mock these dependencies to always give
the response that we expect. Mocking is an important aspect of testing and most
testing frameworks provide support for the mocking. Jasmine allows mocking using
a feature called a spy. Jasmine spies essentially stub the functions that we may not
have ready; at the time of writing the test case but as part of the functionality, we
need to track that we are executing these dependencies and not ignoring them.
Consider the following example:
describe("mocking configurator", function() {
var configurator = null;
var responseJSON = {};
beforeEach(function() {
configurator = {
submitPOSTRequest: function(payload) {
//This is a mock service that will eventually be replaced
//by a real service
console.log(payload);
return {"status": "200"};
}
};
spyOn(configurator,
'submitPOSTRequest').and.returnValue({"status": "200"});
configurator.submitPOSTRequest({
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