unit-threaded ~experimental

unit-threaded

On Linux, use one of ld.bfd, dmd 2.063 or dmd >= 2.065. dmd 2.064.2 + ld.gold won't work. No problem on Windows.

Multi-threaded unit test framework for D. Based on similar work for C++11.

Reasoning

"But doesn't D have built-in unittest blocks"? Yes, and they're massively useful. Even short scripts can benefit from them with 0 effort and setup. In fact, I use them to test this library. However, for larger projects it lacks some functionality:

1. If all tests pass, great. If one fails, it's hard to know why.
2. The only tool is assert, and you have to write your own assert messages (no assertEqual, assertNull, etc.)
3. No possibility to run just one particular test
4. Only runs in one thread.

So I wrote this library in and for a language with built-in support for unit tests. Its goals are:

1. To run in parallel (by default) for maximal speed and turnaround for TDD
2. To make it easy to write tests (functions as test cases)
3. No test registration. Tests are discovered with D's compile-time reflection
4. Support for built-in unittest blocks
5. To be able to run specific tests or group of tests via the command-line
6. Suppress tested code stdio and stderr output by default (important when running in multiple threads).
7. Have a special mode that only works when using a single thread under which tested code output is turned back on, as well as special writelnUt debug messages.
8. Ability to temporarily hide tests from being run by default whilst stil being able to run them

Usage

The library is all in the unit_threaded package. There are two example programs in the example folder, one with passing unit tests and the other failing, to show what the output looks like in each case. Because of the way D packages work, they must be run from the top-level directory of the repository.

The built-in D unittest blocks are included automatically, as seen in the output of both example programs (example.tests.pass_tests.unittest and its homologue in example_fail).

The easiest way to run tests is by doing what the example code does: calling runTests() in runner.d with the modules containing the tests as compile-time arguments. This can be done as symbols or strings, and the two approaches are shown in the examples.

There is no need to register tests. The registration is implicit by deriving from TestCase and overriding test() or by writing a function whose name is in camel-case and begins with "test" (e.g. testFoo(), testGadget()). Specify which modules contain tests when calling runTests() and that's it. Private functions are skipped.

TestCase also has support for setup() and shutdown(), child classes need only override the appropriate functions(s).

Don't like the algorithm for registering tests? Not a problem. The attributes @UnitTest and @DontTest can be used to opt-in or opt-out. These are used in the examples. Tests can also be hidden with the @HiddenTest attribute. This means that particular test doesn't get run by default but can still be run by passing its name as a command-line argument. HiddenTest takes a compile-time string to list the reason why the test is hidden. This would usually be a bug id but can be anything the user wants.

Similarly, @ShouldFail is used to decorate a test that is expected to fail, an also requires a compile-time string. @ShouldFail should be preferred to @HiddenTest. If the relevant bug is fixed or not-yet-implemented functionality is done, the test will then fail, which makes them harder to sweep under the carpet and forget about.

Since D packages are just directories and there the compiler can't read the filesystem at compile-time, there is no way to automatically add all tests in a package. To mitigate this and avoid having to manually write the name of all the modules containing tests, a utility called dtest can be used to generate a source file automatically. Simply pass in the desired directories to scan as command-line arguments. It automatically generates a file, executes it with rdmd, and prints the result. Use the -h option to get help on the command. To try it out, run dtest -usource -t tests/pass to run the passing tests, dtest -usource -t tests/fail to run the failing tests, or simply dtest to run all of them. You can also run either example file with rdmd -Isource example/<filename>.

There is support for debug prints in the tests with the -d switch. This is only supported in single-threaded mode (-s). Setting -d without -s will trigger a warning followed by the forceful use of -s. TestCases and test functions can print debug output with the function writelnUt available here.

Tests can be run in random order. To do so, use the -r option. A seed will be printed so that the same run can be repeated by using the --seed option. This implies running in a single thread.

Since code under test might not be thread-safe, the @SingleThreaded attribute can be used on a test. This causes all tests in the same module that have this attribute to be executed sequentially so they don't interleave with one another.

Related Projects

• dunit: xUnit Testing Framework for D
• DMocks-revived: a mock-object framework that allows to mock interfaces or classes
• deject: automatic dependency injection
• specd: a unit testing framework inspired by specs2 and ScalaTest
• DUnit: a toolkit of test assertions and a template mixin to enable mocking