The ceylon.test module is a simple framework to write repeatable tests.

Tests execute the code of the module under test and can make assertions about what it does. For example,

• do functions, when called with certain arguments, return the expected results?
• do classes behave as required?
• etc.

The usual way to use this module is to write your tests (which make calls to the declarations under test) as top level functions or as methods of top level classes, annotating them with test.

For example, here is a trivial test function, which will always succeed.

test
void shouldAlwaysSucceed() {}

Assertions can be evaluated by using the language's assert statement or with the various assert... functions, for example:

assert(is Hobbit frodo);
assert(exists ring);

assertNotEquals(frodo, sauron);
assertThatException(() => gandalf.castLightnings()).hasType(`NotEnoughMagicPowerException`);

It's also perfectly acceptable to throw [[AssertionException]] directly.

A test function which completes without propogating an exception is classified as a success. A test function which propogates an [[AssertionException]] is classified as a failure. A test function which propogates any other type of Exception is classified as an error.

Test functions can be grouped together inside a class.

class YodaTest() {

    test void shouldBeJedi() {
        assert(yoda is Jedi);
    }

    test void shouldHavePower() {
        assert(yoda.midichloriansCount > 1k);
    }

Common initialization logic can be placed into separate functions, which run before or after each test.

class StarshipTest() {

    beforeTest void init() => starship.chargePhasers();

    afterTest void dispose() => starship.shutdownSystems();

Sometimes you want to temporarily disable a test or a group of tests, this can be done via the ignore annotation.

test
ignore("still not implemented")
void shouldBeFasterThanLight() {

Tests can be run programmatically for a whole module, a package or only individual classes and functions. This is usually achieved using the createTestRunner factory method, most simply by giving it the declaration of the module to be run:

value result = createTestRunner([`module com.acme`]).run();
print(result.isSuccess);

Or by enumerating the things to be tested:

value result = createTestRunner([
        `shouldBeFasterThanLight`,
        `StarshipTest`]).run();
print(result.isSuccess);

Although you can implement the [[TestRunner]] interface directly, createTestRunner has numerous defaulted parameters which usually mean you don't have to.

Using listeners you can react to important events during test execution, or you can exclude particular tests, or execute them in a specific order.

object ringingListener satisfies TestListener {
    shared actual void testError(TestResult result) => alarm.ring();
}

Boolean integrationTestFilter(TestDescription d) {
    return d.name.endsWith("IntegrationTest");
}

Comparison failFastComparator(TestDescription d1, TestDescription d2) {
    return dateOfLastFailure(d1) <=> dateOfLastFailure(d2);
}

TestRunner runner = createTestRunner{
    sources = [`module com.acme`];
    listeners = [ringingListener];
    filter = integrationTestFilter;
    comparator = failFastComparator;
};