ceylon.test new and noteworthy

Module ceylon.test (simple framework for writing repeatable tests) is an integral part of Ceylon SDK since its first version and in the latest release 1.2.1 brings several handy new features, namely:

Let's look at them in more details.

Parameterized tests

Parameterized tests allow developers to run the same test over and over again using different values, where each invocation of a test function is reported individually. A classical example for usage of parameterized tests is with a function computing Fibonacci numbers.

shared {[Integer, Integer]*} fibonnaciNumbers => 
    {[1, 1], [2, 1], [3, 2], [4, 3], [5, 5], [6, 8] ...};

parameters(`value fibonnaciNumbers`)
shared void shouldCalculateFibonacciNumber(Integer input, Integer result) {
    assert(fibonacciNumber(input) == result);

In this example, we use annotation parameters to specify the source of argument values, which will be used during test execution. You can use any top level value or unary function with a compatible type as the source of argument values. The argument provider can be specified for the whole function, as in this example, or individually for each parameter, then the test framework will execute the test for each combination of provided values. For example, a function with one parameter whose argument provider yields two values and a second parameter whose argument provider yields three values, will be executed six times.

This functionality is based on a general mechanism, which can be easily extended, e.g. serving values from data file or randomized testing. For more information see documentation to ArgumentProvider and ArgumentListProvider.

Conditional execution

In some scenarios, the condition if the test can be reliable executed is known only in runtime. For this purpose it is useful to be able explicitly declare those assumption, as for example in following test. When the assumption is not met, verified with assumeTrue() function, then the test execution is interupted and the test is marked as aborted.

shared void shouldUseNetwork() {

Alternatively, it is possible to specify test condition declaratively, via custom annotation which satisfy SPI interface TestCondition. In fact the ignore annotation is just simple implementation of this concept.

Grouped assertions

Sometimes you don't want to interrupt your test after first failed assertions, because you are interested to know all possible failures. In that case you can use assertAll() function, which will verify all given assertions and any failures will report together.

    () => assertEquals(agent.id, "007"),
    () => assertEquals(agent.firstName, "James"),
    () => assertEquals(agent.lastName, "Bond")]);

Tagging and filtering

Test functions/methods and their containers (classes, packages) can be tagged, via annotation tag. For example, a test which is failing randomly for unknown reasons can be marked as unstable.

shared void shouldSucceedWithLittleLuck() { ... }

Those tags can later be used for filtering tests. Either in inclusive style (only tests with specified tag will be executed).

$ceylon test --tag=unstable com.acme.mymodule

Or visa versa for exclusion (only tests without specified tag will be executed).

$ceylon test --tag=!unstable com.acme.mymodule

Extension points

Extension points are general mechanisms which allow to extend or modify default framework behavior and better integration with 3rd party libraries (e.g. custom reporters, integration with DI frameworks). The easiest way to register extensions is with annotation testExtension, which can be placed on test itself, or on any of its container. Currently the following extension points are available, and new ones can be added if needed:


These two last features have already been available for some time, but they could easily have slipped your attention. The first is nice html report with results of test execution, to enable it, run the test tool with --report option, it will be generated under report/test(-js) subdirectory.

The second is support for Test Anything Protocol (TAP), which allow integration with CI servers. To enable run the test tool with --tap option.

And if you don't have enough, just look on excellent library, built on top of ceylon.test which enables BDD style of test development and much more, called specks.