Assertion Framework

Although MQL4 is pretty close syntactically to C++, it lacks a lot of C++ features such as multiple inheritance, runtime type information (RTTI) and exceptions.

Traditionally, in JUnit and CppUnit assertion failures are thrown as exceptions. Unfortunately this can't be done in MQL4. Although MQLLIB includes some rudementary exception emulation layer, it is unsuitable for our purposes here.

The following convention, therefore, has been established. Assertion methods of MQLUNIT_Assert class return string value. The value is set to NULL if the assertion was successful, otherwise the method returns a message parameter passed to the function (which is a user defined failure description).

Please take time to examine MQLUNIT_Assert class and corresponding MQLUNIT_AssertTest test case to understand an assertion framework of MQLUNIT.

Test Execution Model

All test cases and test suites are derived from MQLUNIT_Test class. Each test is executed by calling MQLUNIT_Test::run method. End users of MQLUNIT never implement MQLUNIT_Test::run directly. Instead they use a set of macros that builds this method.

MQLUNIT_START starts the implementation of MQLUNIT_Test::run method.

Each pair of TEST_START and TEST_END macros adds a code for a particular test method inline right into MQLUNIT_Test::run implementation body.

ASSERT macros run assertions and add any encountered failures as MQLUNIT_TestFailure to the list of test failures.

MQLUNIT_END macro finishes the MQLUNIT_Test::run implementation.

Set Up and Tear Down

As in JUnit and CppUnit, MQLUNIT_TestCase defines MQLUNIT_TestCase::setUp and MQLUNIT_TestCase::tearDown methods. MQLUNIT_TestCase::setUp is executed before each test method and MQLUNIT_TestCase::tearDown is executed after each test method.

TEST_START and TEST_END macros are responsible for this functionality.

Event System

MQLUNIT includes MQLUNIT_TestListener interface that defines events that get emitted during the test execution. Separate events are emitted when test case execution starts, before and after each test method and at the end of the test case.

These events are fired by MQLUNIT_START, TEST_START, TEST_END, and MQLUNIT_END macros and are embedded into the generated MQLUNIT_Test::run implementation.

In the case of assertion failure, the appropriate ASSERT macro fires the event.

MQLUNIT_TestResult collector class contains the list of registered MQLUNIT_TestListener and calls event handling methods on each one of them.

Test Hierarchy

It is possible to build a test hierarchy off MQLUNIT_Test. The child test's implementation of MQLUNIT_Test::run is responsible for calling MQLUNIT_Test::run implementation on its parent. Helper macro MQLUNIT_INHERIT has been added for this purpose. It makes sure the parent's MQLUNIT_Test::run implementation is called and passes an inherited parameter set to true. The purpose of this parameter is to prevent parent test from firing events on a test case start and a test case end (the child test fires them and, essentially, wraps a parent test).